Outreach mpox vaccination at sex-on-premises venues in Sydney: an audit of a collaborative intervention by public health nurses and LGBTQI+ peer workers

Abstract

Introduction and aims

In 2024, in response to a re-surge in mpox transmission in New South Wales, Australia, Kirketon Road Centre (KRC) partnered with an HIV and LGBTQI+ community organisation, ACON, to conduct outreach vaccination in two sex-on-premises venues (SOPVs), also known as “saunas”. SOPV attendees were approached by an ACON peer worker who offered health education and referral to on-site mpox vaccination (Jynneos®) by a registered nurse. We aim to describe the scope, the acceptability, and the outcomes of mpox vaccination outreach at SOPVs in Sydney, and compare characteristics of people who received mpox vaccination at SOPVs to those who were vaccinated for mpox at a KRC’s fixed-site vaccination clinic.

Methods

In addition to a descriptive analysis of service records, we matched individual-level records with Australian Immunisation Register (AIR) and ran (comparative) descriptive and multivariate analyses; a subset of people who were matched on AIR was analysed.

Results

During the outreach period, KRC administered 639 mpox vaccines at its fixed-site and conducted 22 outreach sessions at SOPVs in collaboration with ACON. These sessions resulted in 840 engagements; 522 individuals were eligible for mpox vaccination, 407 (78%) accepted referral to a nurse vaccinating onsite at SOPV, and n = 359 received mpox vaccine at SOPV. Among individuals who were matched on AIR, 77% at KRC’s fixed-site and 66% at SOPV received two doses of mpox vaccine at some point. People who received at least one mpox vaccine at an SOPV were older (mean 46 vs. 39 years) and were less likely to: reside locally (34% vs. 51%), to have Medicare (57% vs. 74%), or to have an AIR record (60% vs. 67%) than people who were vaccinated at KRC's fixed site only. In a multivariate model, vaccine completion was not associated with receiving SOPV vs. KRC’s fixed-site.

Conclusion

Mpox outreach vaccination done in collaboration between nurses and LGBTQI+ peer-workers at SOPVs proved feasible, acceptable, and beneficial in terms of reaching people who may be out of area and not routinely engaged with sexual health services. Models of care that circumnavigate traditional geographic and local health service barriers should be considered during outbreaks, particularly those that build on established rapport within the communities at risk, such as MSM.

Background

Mpox is caused by the monkeypox virus with its two distinct virus clades [1]. Mpox is mainly transmitted through sustained close physical contact, including sexual contact, with someone who has mpox, for example, in households and venues that offer sex-on-premises, and as well as through contact with shared surfaces, furniture, or linen [2, 3]; more research is needed regarding respiratory [4] or maternal-foetal routes of transmission [5]. In 2022–2023, a global outbreak of mpox clade IIb resulted in more than 100,000 cases in 127 countries; most cases have been in males, primarily gay, bisexual and other men who have sex with men [6]. Health authorities first detected mpox in Australia in May 2022, which led to 144 cases being reported during the 2022 outbreak [7]. During this initial wave of vaccination, due to shortages in supply, many people received just one dose of the mpox vaccine intradermally [8]. In 2024, local mpox transmission increased in New South Wales (NSW), exceeding two hundred notifications by August 2024 [9]. This was an unexpected resurgence of the virus, following successful efforts to curb the spread in 2022–2023 via a prompt public health campaign [7] .

Among the various strategies proposed to mitigate mpox outbreaks, administering mpox vaccine at “saunas’ or other sex-on-premise venues (SOPVs) has been identified as a promising approach [10]. As well as providing communal bathing facilities, the saunas provide a location for patrons to engage in consensual sexual activities, typically on an informal and non-commercial basis. Such settings provide anonymity and are often attended by men who have sex with men (MSM) but may not self-identify as gay [11]. As such, SOPVs have been identified as important potential locations for HIV and other STI acquisition for over a decade [11], and therefore, sexual health services and community organisations have conducted outreach into SOPVs to offer access to STI testing [12, 13]. Despite existing outreach services, vaccination programs at SOPVs remain limited [14].

Established in 1987, The Kirketon Road Centre (KRC) is a publicly funded community health service designed to deliver free, low-threshold, harm-reduction-focused care. KRC is part of the Sexual Health and Blood-Borne Virus team which encompasses a network of clinics across Sydney’s South Eastern Sydney Local Health District. KRC primarily targets populations at risk, including people who inject drugs, sex workers, people experiencing homelessness, and young people under 25 who are at risk or affected by these factors. It also prioritises individuals requiring testing or treatment for sexually transmissible infections, HIV, hepatitis B and C; provides pre- and post-exposure prophylaxis for HIV; and engages in targeted outreach and health promotion, such as vaccination, to increase access among high-risk groups. Mpox vaccination has been a core part of KRC’s services since 2022.

The 2024 mpox resurgence in NSW triggered a public health and service response to deliver mpox vaccination to at-risk MSM. As part of a response by the local sexual health sector to maximise mpox vaccination uptake, KRC partnered with ACON (a community HIV and LGBTQ+ health organisation, formerly known as the AIDS Council of NSW), to conduct outreach vaccination in “saunas” within the geographic remit of the Local Health District under which KRC operates. Two SOPVs accepted the offer for vaccine outreach sessions (aliased as Sauna I and Sauna II) and these were conducted between September and December 2024. On a typical week, an outreach shift was conducted into each of those venues on two consecutive days. SOPV attendees were approached by an ACON peer worker first; the peer worker offered health education and those who were interested in mpox vaccine (Jynneos®) were referred to the accredited registered nurse immuniser for the vaccination. All participants were monitored for 15 min post-vaccination.

This paper aimed to describe the scope, the acceptability, and the outcomes of mpox vaccination outreach at SOPVs in Sydney. It also aimed to compare characteristics of people who received mpox vaccination at SOPVs to those who were vaccinated for mpox at a KRC’s fixed-site vaccination clinic during the same period.

Materials and methods

Program setting – collaboration with SOPVs and the role of ACON’s peer-workers

Outreach vaccinations in saunas were run in partnership between ACON’s peer-workers and KRC nurses, including nurses from other local Sexual Health and Blood Borne Virus Services, and in collaboration with the SOPV venues. As part of the vaccination partnership, SOPV venues advertised mpox vaccination dates on their social media pages. SOPVs also provided free entry for those attending solely for vaccination and offered a free pass for a future visit to clients who received the mpox vaccine. SOPVs offered private rooms or partitioned spaces suitable for clinical procedures. Vaccination rooms were chosen for their ability to offer discreet spaces. KRC’s Nursing Unit Manager and ACON’s Peer Team Manager conducted site visits to the venues in beforehand to ensure adequate lighting in the vaccination space; waiting areas, on the other hand, were chosen to minimise attendee’s visibility. On the day of the vaccination outreach, client flow was managed by staggering entry into vaccination rooms.

To maximise impact at SOPVs, ACON launched an mpox awareness-rising campaign, featuring the statistics regarding increasing cases of mpox in NSW and highlighting the need for vaccinations. The campaign included displaying posters at all SOPVs in Sydney and at publicly funded sexual health clinics. A social media campaign was run in parallel by ACON, and was targeted to various geolocations, including SOPV locations. MPOX information brochures and business cards with explorable links were left in SOPV lockers in change rooms, and in well-lit areas across the venues.

On the days of mpox vaccination outreach, pull-up banners and signs were placed at entry ways of the SOPVs, referencing the campaign with QR codes and URL links. Announcements of the vaccination taking place were made by SOPV staff over intercom (e.g. “ACON staff are here today, supporting the delivery of MPOX vaccinations. If you are interested in knowing more about MPOX or have any questions related to vaccination, please visit them at XX location”.) On top of the campaign signage, and additional poster stated that the vaccination was “free, no Medicare required”. Peer workers were clearly dressed in ACON branded clothing which enabled distinguishing them from SOPV or nursing staff, and associating them with ACON which has a reputation in addressing the LGBTQ+ health needs and in conducting HIV/STI screening initiatives.

At SOPV venues, peer-workers leveraged their existing relationships and lived experience as gay, bisexual, and other men who have sex with men (MSM) when building trust in the community and initiate non-intrusive conversations. Peer-workers were stationed near the entrance to vaccination rooms and approached clients with open-ended questions such as whether they had heard about MPOX or were interested in vaccination. Peer-workers also facilitated initial screening for eligibility, i.e. people who already received two doses of the vaccine were not being referred to get another one. For clients who were hesitant, peers provided reassurance about privacy and explained the benefits of vaccination in a culturally sensitive, stigma-free way.

Clients that raised concerns about pre-existing health conditions were encouraged to speak to the nursing team to assess what their personal considerations were. Peer-workers were not involved in discussion with nurses unless the client had asked them for additional support. At SOPVs, peer -workers operated under existing organisational codes of conduct (for ACON, and, specifically, for ACON’s HIV-testing program called “a[TEST]” [15]), prioritising participant’s privacy. No identifying data was collected by peer-workers; their role was limited to providing information, distributing consent forms (filling out the forms was handled directly by clinical staff), and gauging willingness to get vaccinated. They told attendees that phone numbers, emails, addresses etc. were not necessary to be completed on the consent form, only their chosen name and chosen DOB was mandatory (attendees were told that they didn’t have to use their real name and date of birth, as long as it matched with their second vaccination). Unless agreed upon, information would not be uploaded to a digital record system. All interactions with attendees were completed within the SOPVs to ensure that there was no accidental “outing” of clients, limiting any opportunities for stigmatisation.

Nurse-led mpox vaccine consent and dose administration

SOPV attendees who were interested to receive an mpox vaccine onsite were directed by peer-workers to the waiting area or, if there was no wait time, directly into the clinical room. They were asked to fill out Jynneos^® consent form, and were supported by the nurse to do so if required. The consent form was reviewed by the nurse and checked for allergies or any medical issues. The client was given the opportunity to ask questions and could decline the vaccine if they had any change of mind. If there was an area of concern, such as a query around a previous vaccine reaction, the medical officer on call was consulted via phone, with the option to receive the mpox vaccine at KRC's fixed site instead needed. The same nurse-led process was followed during mpox vaccination outreach at SOPVs and at KRC’s fixed clinic.

For those who had a record on AIR, and allowed the nurse to access it, this record was always checked before proceeding with the vaccination. Alternatively, the nurses relied on participants informing them if they had been vaccinated or not (past vaccination and its date were recorded on the consent form). People who already had received two doses of the vaccine, who had their first dose less than four weeks ago, or who had small pox or mpox recently were not eligible and thus not given mpox vaccine on that occasion. For those who were eligible, with additional consent, mpox vaccinations at SOPVs (and at KRC’s fixed-site) were recorded on the Australian Immunisation Register (AIR). This step was not made mandatory by the authorities because mpox vaccination targeted specific at-risk MSM populations who may wish not to be identified as such by other health providers. After vaccination (on both SOPV outreach and at KRC's fixed site), clients were observed for a short period in a designated area to monitor for adverse reactions.

Data collection - service-level and client-level data

During each outreach sessions at SOPVs, ACON peer workers collected service-level data on the number of engagements, vaccination acceptance, and self-reported vaccination history (no identifiers were retrieved by peer-workers).

Clinical, individual-level data were also included and consisted of routinely-collected records that were part of the service provision by the nurses. The data used in this analysis consisted of information provided on Jynneos^® consent forms, and for people vaccinated at KRC’s facility (“fixed site”) also from its internal medication management system. This data was matched with records from the Australian Immunisation Registry (see details below).

Data from Jynneos^® consent forms were transcribed for this study, to form a set of participants who were vaccinated against mpox at SOPV outreach. For participants who received an mpox vaccine at KRC’s fixed-site, we extracted their details from KRC’s medication management system.

All data were managed in accordance with NSW Health privacy, ethics, and data-governance requirements. Identifiable SOPV forms were stored securely within NSW Health—paper forms in locked cabinets and electronic files in password-protected folders accessible only to authorised members of the study team. SOPV clients were not required to provide Medicare numbers, and no proof of identity was requested; only name and date of birth were collected for service delivery purposes.

The process of matching with Australian immunisation registry

Both the SOPV and KRC's fixed-site dataset were matched against mpox vaccination records in AIR using client’s name, date of birth, and Medicare number when available (neither SOPV nor KRC fixed-site participants were required to provide this number nor have their vaccination recorded on AIR; participants may have had a Medicare record but not an AIR record and the other way around - this would be the case when recently Medicare-eligible individuals have not had vaccinations in Australia, or when Medicare ineligible participants had a vaccination recorded on AIR, respectively). Matching allowed us to retrieve information on any additional mpox vaccinations administered by other providers. AIR records were also used to complement missing postcode data. In addition, we assessed the proportion of participants who could be matched on AIR as a stand-alone variable, and also reported on the proportion of participants who didn’t have at least one of their mpox doses recorded on AIR.

In the process of matching, a report including all participants with any vaccination history was requested from the AIR. A unique identifier was created in both the AIR report and the SOPV and KRC's fixed-site client lists from the first two letters of the last name, first name, and date of birth, and data were consolidated to one record per client with the number of doses received. These processed results were then matched back to the original client list using the unique identifier. The AIR report and the SOPV and KRC's fixed-site client list were compared using VLOOKUP in Microsoft Excel to identify and correct variations in names and Medicare numbers. Data cleaning and processing were conducted in RStudio (R version 4.4.1).

An anonymised dataset comprising of individual-level data, date of 1st and 2nd mpox vaccination (when applicable), residential postcode availability, whether the available postcode was in the same Local Health District, whether the person had Medicare (when available), and whether they were on AIR was used for the analysis.

Access to Australian Immunisation Register (AIR) data (see below) occurred under NSW Health’s existing business-as-usual public health functions for vaccine surveillance. For linkage, identifying fields (name, date of birth, and Medicare number when voluntarily provided) were used solely within secure NSW Health systems. A temporary linkage key, created from the first two letters of the first and of the last name plus date of birth, was used to minimise handling of directly identifiable information during data processing. After linkage, records were consolidated into a single de-identified analytical record per participant containing vaccination history and non-identifiable demographic variables. No directly identifiable information was retained in the final dataset for analysis. The process of retrieving, analysing, and publicising the data was reviewed by Low Negligible Risk Committee of the South Eastern Local Health District on 25 February 2025 and deemed as not raising any ethical concerns.

Missing data handling

Missing information in key variables (including whether participants had an AIR record, and whether they had their mpox vaccine recorded) was considered potentially informative—reflecting factors such as privacy concerns, inconsistent identifier use, or limited healthcare engagement. As such, missing data were treated as stand-alone analytical indicators rather than removed or imputed. Binary variables were created to represent absence of an AIR record and absence of a known mpox dose in participants’ AIR record. These variables were incorporated into descriptive analyses and multivariate logistic regression models. For all other variables, analyses were performed using available-case (complete-case) data. No imputation was undertaken, as patterns of missingness were not assumed to be random. Potential implications of this approach, including misclassification due to administrative errors, are discussed in the Limitations section.

Analysis

A descriptive analysis of service data collected by ACON’s peer workers was used to report on the number of engagements at SOPVs, vaccination eligibility, self-reported vaccination history, and willingness to receive an mpox vaccine onsite at the SOPV (i.e. referral made to the onsite vaccinating nurse).

Next, a descriptive analysis of clinical data was run to examine the characteristics of people who were vaccinated at SOPVs and at KRC’s fixed-site. The descriptive analysis used individual-level data that was available from Jynneos^® consent forms (date of birth, previous vaccination) and from AIR (for matched participants) to assess mpox vaccine course completion and postcode of residence. Chi² and t-tests were used to compare these two groups.

An additional analysis included restricting the comparative descriptive analysis above to people who could be matched with AIR records (67% of participants who received mpox vaccine at a fixed site and 60% of those at SOPV). This was relevant because unmatched participants had inherent data gaps in key variables obtained through AIR, including postcode, Medicare number availability, and in their records of additional mpox doses administered by other providers.

Finally, a multivariate analysis examined factors associated with receiving an mpox vaccine at an SOPV versus at a fixed site. Participant age, postcode availability, residence within the Local Health District, Medicare number availability, and mpox vaccine completion (two doses) were used as covariates. We also controlled for a variable we created – “having at least one of their mpox doses NOT recorded on AIR”, i.e. they were provided an mpox vaccine at SOVP or KRC’s fixed-site yet this dose either could not be found on AIR or the participant didn’t have any AIR records at all; we chose this indicator as a proxy for participants potentially not wanting to identify as MSM, although the reasons may vary.

Results

Descriptive analysis of service data

Between September and December 2024, KRC and ACON conducted twenty-two outreach clinics across two SOPVs. The mean number of mpox vaccines administered per outreach session was n = 16 (median was n = 13); with a range of 3 to 41 doses per clinic (see Fig. 1).

Fig. 1.

Number of accepted referrals to a nurse administering mpox vaccine onsite at sex-on-premises venues (SOPVs - Sauna I. and Sauna II), September - December 2024

There were n = 840 recorded engagements by ACON’s peer-workers at SOPVs. In n = 300 engagements (36%), the person stated they had already been fully vaccinated against mpox, n = 18 (2%) were unable to consent; deeming n = 522 (62%) engagements with participants who were eligible for mpox vaccination at an SOPV.

From eligible engagements, on n = 115 (22%) occasions, participants declined mpox vaccination onsite at an SOPV. A total of 407 referrals for mpox vaccinations to a nurse onsite at SOPV were recorded, representing 78% of eligible engagements (or 49% of all engagements). The number of unique participants referred for mpox vaccination onsite at SOPVs could not be determined from ACON’s data, but we analyse this in the following section (Fig. 2).

Fig. 2.

Flow-chart of occasions of service (client engagement and mpox vaccination referrals to a nurse onsite) during mpox vaccination outreach at sex-on-premises venues (SOPVs). Source of data: Peer-worker engagement logs

Descriptive analysis of clinical data

From the Jynneos^® consent forms, we identified n = 331 unique participants who received an mpox vaccination during SOPV outreach over the study period. Some participants received more than one dose, resulting in a total of n = 359 mpox vaccine doses administered during outreach which we included in client-level analysis. The discrepancy from the n = 407 referrals for onsite mpox vaccinations reported in the previous section was caused by several reasons, including additional ineligible participants (when nurse identified they had two mpox doses already), participants who had their first dose less than four weeks ago, or had small pox or mpox infection in the past, and participants having change of mind and decided not to go forward with the vaccine.

During the same period, n = 502 participants were vaccinated for mpox at a fixed site; accounting for a total of n = 639 mpox vaccine doses. There was a small overlap between participants who received mpox vaccines at SOPV and KRC’s fixed-site: seven people received their first mpox vaccine at an SOPV and their second at KRC’s fixed-site, while one person received their first dose at KRC and their second at an SOPV. For the purposes of this analysis, all eight participants were classified as SOPV participants.

People vaccinated in SOPVs were, on average, older than those vaccinated at KRC’s fixed-site, with a mean age of 46 years compared to 39 years (t = -7.01, p < 0.001). SOPV participants were less likely to have an AIR record (60% vs. 67%, χ² = 4.46, p = 0.035) and less likely to have Medicare (57% vs. 74%, χ² = 26.54, p < 0.001), see Tables 1 and 2 for details.

Table 1.

Comparison of participants by mpox vaccination venue - sex on premises venues (SOPVs) vs. Kirketon road centre’s (KRC’s) fixed site with respect to age and dosing interval among; all participants and sub-group of participants who were matched in Australian immunisation registry (AIR)

	All participants			Participants who were matched on AIR †
	KRC's fixed site (N = 490), Mean ± SD	SOPV (N = 331), Mean ± SD	Test Statistic (p-value)	KRC's fixed site (N = 327), Mean ± SD	SOPV (N = 197), Mean ± SD	Test Statistic (p-value)
Age (years)	38.6 ± 12.6	45.5 ± 15.7	t = -7.01 (p < 0.001)	39.0 ± 13.2	46.9 ± 14.5	t = -6.39, (p < 0.001)
Number of days between vaccine doses (for those fully vaccinated)	133.6 ± 232.0	200.0 ± 278.5	t = -2.62 (p = 0.009)	145.5 ± 243.8	200.5 ± 284.8	t = -1.93 ( p  = 0.054)
No of days when both doses received at the same site	37.4 ± 13.2	42.6 ± 14.5	t = -1.85 (p = 0.066)	36.3 ± 12.8	39.0 ± 8.1	t = -0.97 ( p  = 0.334)

Source of data: Jynneos^® consent forms; Australian Immunisation Registry records, KRC’s internal medication management system

There was no statistically significant difference between all vaccinated participants vs. those matched on AIR record within each group (KRC's fixed site and SOPV), when assessed upon the presence of overlap between their 95% confidence intervals (no overlap meaning significant difference)

^†Participants who were vaccinated and had an AIR record are a subset of all participants reported in previous columns

Table 2.

Comparison of participants by mpox vaccination venue - sex on premises venues (SOPVs) vs. Kirketon Road Centre's (KRC's) fixed site with respect to Medicare, AIR record, postcode data, and vaccine completion; all participants and sub-group of participants who were matched in Australian immunisation registry (AIR)

	All participants			Participantswho were matched on AIR†
	KRC's fixed site (N = 490), n (%)	SOPV (N = 331), n (%)	Chi2 Test, (p-value)	KRC's fixed Site (N = 327), n (%)	SOPV (N = 197), n (%)	Chi2 Test (p-value)
Has an AIR record	327 (66.7)	197 (59.5)	χ² = 4.46 ( p  = 0.035 )	327 (100)	197 (100)	n.a.
Has Medicare	364 (74.3)	189 (57.1)*	χ² = 26.54 ( p  < 0.001 )	272 (83.2)	169 (85.8)*	χ² = 0.63 (p = 0.429)
Postcode information available	385 (78.6)	170 (51.4)*	χ² = 66.79 (p<0.001)	316 (96.6)	170 (86.3)*	χ² = 19.55 (p < 0.001)
From those with postcode info, resides in the Local Health District¥	215 (55.8)	58 (34.1)	χ²=61.82 ( p  < 0.001 )	177 (55.8)	58 (34.1)	χ² = 22.27 (p < 0.001)
Fully vaccinated (i.e. two mpox vaccines)	283 (57.8)	146 (44.1)*	χ² = 14.75 (p < 0.001)	251 (76.8)	122 (62.0)*	χ² = 13.18 (p < 0.001)
Only 1st dose received at the site	32 (6.5)	37 (11.2)	χ² = 5.54 ( p  = 0.019 )	32 (9.8)	37 (18.8)	χ² = 8.70 (p = 0.003)
Only 2nd dose received at the site	118 (24.1)	80 (24.2)*	χ² = 0.00 (p = 0.977)	118 (36.1)	61 (31.0)	χ² = 1.43 (p = 0.231)
Both doses received at the same site	133 (27.1)	28 (8.5)	χ² = 43.74 ( p  < 0.001 )	101 (30.9)	23 (11.7)	χ² = 25.12 (p < 0.001)
Has had at least one of their mpox doses unrecorded on AIR	16 (3.3)	26 (7.9)	χ² = 8.57 ( p  = 0.003 )	16 (4.9)	26 (13.2)	χ² = 11.50 (p = 0.001)

Source of data: Jynneos^® consent forms; Australian Immunisation Registry records, KRC’s internal medication management system

In bold italics is statistically significant difference between participants at SOPV and at a fixed site

^¥ The Local Health District in this study was Sydney’s South Eastern Local Health District, New South Wales Health

 *Statistically significant difference between all vaccinated participants vs. those who were matched on AIR record within each group (KRC's fixed site and SOPV), assessed upon the presence of overlap between their 95% confidence intervals (no overlap meaning significant difference)

^†Participants who were vaccinated and had an AIR record are a subset of all participants reported in previous columns

Postcode information was available for fewer SOPV participants than those vaccinated at KRC’s fixed-site (51% vs. 79%, χ² = 66.79, p < 0.001). Among those with postcode data, only 34% of people vaccinated at SOPV resided in the Local Health District compared to 56% of those who were vaccinated at KRC’s fixed-site (χ² = 61.82, p < 0.001).

SOPV participants were less likely to be fully vaccinated (44% vs. 58%, χ² = 14.75, p < 0.001) and were more likely to have at least one mpox vaccine dose unrecorded in AIR (8% vs. 3%, χ² = 8.57, p = 0.003).

People vaccinated at KRC’s fixed-site clinic were more likely to receive both mpox vaccine doses there (27%), compared to just 9% of SOPV participants who received both doses at SOPV (χ² = 43.74, p < 0.001). Conversely, people vaccinated at SOPV were more likely to only receive their first dose there (11% vs. 7%, χ² = 5.54, p = 0.019). Among those fully vaccinated, the average number of days between doses was significantly higher in the SOPV group (200 days vs. 134 days, t = -2.62, p = 0.009; the number of days was lower for participants who received both doses at the same site, being 42 days at KRC’s fixed-site and 37 days at SOPV), 28 days being the minimum and recommended time between doses.

Comparative descriptive analysis of subset of participants who were matched on AIR

From participants who could be matched with a profile on AIR, n = 327 participants received an mpox vaccine at KRC’s fixed-site and n = 197 participants received a vaccine at SOPV.

In the AIR-matched sub-sample, people vaccinated at SOPV remained significantly older than those vaccinated at KRC’s fixed-site (47 vs. 39 years, t = -6.39, p < 0.001). However, a similar proportion of AIR-matched SOPV participants and AIR-matched participants at KRC’s fixed-site had Medicare (86% and 83%, respectively), see Tables 1 and 2 for details.

More postcode data was available for AIR-matched than for non-matched participants, reflecting the fact that was where postcode information was largely retrieved from; however, the difference between the groups remained significant (97% of participants from KRC’s fixed-site and 86% participants from SOPV had a postcode available, χ² = 19.55, p < 0.001).

Importantly, when looking only at people who were matched on AIR, a significantly higher proportion of participants compared to the non-matched ones received two doses of the mpox vaccine (77% of participants at KRC’s fixed-site received two doses vs. 58% of SOPV participants, χ² = 13.18, p < 0.001).

Odds of receiving mpox vaccination at SOPV vs. at KRC’s fixed-site

The multivariate logistic regression was used to explore the odds of receiving mpox vaccination at an SOPV vs. at KRC’s fixed-site, adjusting for all covariates. The findings corroborated those of the comparative descriptive analysis (see Table 3).

Table 3.

Factors associated with receiving mpox vaccination at sex on premises venues (SOPVs) vs. at KRC's fixed site; bivariate and multivariate logistic regression models predicting vaccination at SOPV

Variable	Bivariate Logistic Regression OR (95% CI)	p-value	Multivariate Logistic Regression AOR (95% CI)	p-value
Age (years)	1.036 (1.025–1.047)	< 0.001	1.047 (1.035–1.060)	< 0.001
Postcode data available (Yes)	—	—	0.565 (0.368–0.869)	0.009
Local Health District postcode (Yes)†	0.272 (0.194–0.380)	< 0.001	0.376 (0.253–0.560)	< 0.001
Has Medicare (Yes)	0.464 (0.345–0.625)	< 0.001	0.536 (0.368–0.782)	0.001
Fully vaccinated (i.e. two mpox vaccines, Yes)	0.577 (0.436–0.765)	< 0.001	0.785 (0.545–1.131)	0.193
Has had at least one of their mpox doses unrecorded on AIR (Yes)††	2.531 (1.336–4.795)	0.004	4.023 (1.962–8.248)	< 0.001

Source of data: Jynneos^® consent forms; Australian Immunisation Registry records, KRC’s internal medication management system

† Participants with no postcode info were coded as “not Local Health District postcode” in the multivariate model. The Local Health District in this study was Sydney’s South Eastern Local Health District, New South Wales Health

†† This includes participants who received an mpox vaccine dose at SOPV or at KRC's fixed site, but either could not be matched with a profile on AIR or did have an AIR profile but their mpox vaccine dose wasn’t’ recorded there

In the model, each additional year of age increased the likelihood of receiving mpox vaccination at an SOPV rather than at KRC’s fixed-site by 5% (p < 0.001). Participants residing in the Local Health District were 61% less likely to receive an mpox vaccine at SOPVs (p < 0.001). Not having Medicare was associated with a 48% increase in the odds of receiving an mpox vaccine at an SOPV (p = 0.001). Having at least one mpox dose unrecorded on AIR increased the odds of receiving the mpox vaccine at an SOPV by 382% (p < 0.001).

In the multivariate model, receiving two doses of the mpox vaccine (“fully vaccinated”) wasn’t significantly associated with the vaccination site, suggesting that vaccine completion was more influenced by participant characteristics and data completeness than by the vaccination site alone.

Discussion

Mpox outreach vaccination administered at SOPVs proved both beneficial and acceptable, with majority of eligible participants agreeing to receive an mpox vaccination there. Given the success of the mpox vaccination outreach at SOPVs in engaging priority populations, SOPV-based vaccination models should be included in future public health responses targeting MSM.

Compared to participants vaccinated at the KRC’s fixed-site, those vaccinated at SOPVs were older and less likely to reside in the Local Health District. Indeed, our research showed that participants vaccinated at SOPV were more likely to have an incomplete vaccination record on AIR (i.e. received more mpox doses from us than what was recorded on AIR), which may indicate higher concern about confidentiality. These findings align with a previous study which found that men attending SOPVs were older than those coming to a fixed sexual health clinic, were more commonly married or widowed to a woman, were at higher risk of sexually transmissible infections, and attended for less testing for thereof and for HIV compared to participants from a fixed-site clinic [16]. The difference in postcode suggests that men who were vaccinated at SOPVs may have travelled from other health districts to access these venues while maintaining confidentiality. As such, the mpox vaccination outreach into SOPVs reached outside of the borders of the Local Health District, and may have contributed to the successful public health campaign in NSW which saw the number of new mpox notifications decrease from 219 in September 2024 [17] to 16 in January 2025 [18], see Fig. 3 for details.

Fig. 3.

Monthly SOPV notifications in NSW between June 2024 - May 2025. Source of data: NSW Mpox surveillance reports (the monthly figures have been estimated from weekly reports)

The fixed-site vaccine completion rate we report here is consistent with other studies of mpox vaccine completion. A recent study reporting on mpox vaccination rates from a survey among MSM found that among n = 4,252 participants in Australia, 41.5% had received both doses of the vaccine, 12.3% had received one dose, and 46.2% were unvaccinated. Overall, 77% of people receiving any vaccine had received two doses of mpox; this respective proportion was 79% among n = 1214 men in Sydney [19]. An audit of mpox vaccine records in NSW indeed found that approximately 75–76% of people who received at least one dose of mpox vaccine also received their second [8].

The lower rate of achieving full vaccination among SOPV participants could be explained by the characteristics of the participants, indicating that people not typically reached by conventional sexual health services in the Local Health District were engaged at SOPVs. SOPV outreach may indeed have engaged participants who were more likely to be non-residents of Australia or who were not well-integrated into the formal healthcare system. These men may have been missed by public health campaigns that target more mainstream MSM and, as such, have less access to information about mpox. Indeed, SOPV participants experienced longer delays between their two mpox doses, suggesting they may have been experiencing additional barriers to accessing mpox vaccines. From their AIR record or self-report, 78 people had their first vaccine dose in 2022 or 2023; of those, 41 participants had their 2nd dose at a fixed site (8%) and 37 (11%) had it at SOPV during the outreach campaign period). These people were given their 2nd dose as usual. As such, the SOPV outreach (slightly more than the a fixed site) may have filled in a gap by accessing an otherwise under-serviced population of MSM at risk. The findings of Medicare and postcode differences in SOPV participants may also suggest that outreach and other non-traditional models of care for outbreaks should be considered at a state or national level, including funding initiatives to deliver effective outbreak control and circumnavigate traditional geographic and local health service barriers.

The success of this model relied heavily on pre-existing trust between SOPVs and ACON, highlighting the value of long-term community partnerships for rapid public health responses. The SOPVs giving access to the venue was essential, and the program was facilitated by an extensive health-education campaign from ACON (targeted, not limited to the SOPV venues). The partnership between public health nurses and ACON peers was, indeed, critical. Peers focused on engagement and education, while nurses handled clinical tasks. Clear role delineation and pre-event planning ensured smooth coordination; there was a clear benefit in making joint visits to the SOPV sites to assess for suitability before the outreach program started. Peer-workers presence on the outreach shifts ensured a warm entry point into the clinical process. Many peer-workers who worked on the mpox outreach program had a prior experience of working for the a[TEST] project [15, 20] and as such, they had a pre-existing understanding of motivational interviewing, knowledge of HIV and STIs, and experience in community-led practice.

Public health and policy implications

The findings of this study demonstrate that outreach vaccination in informal, community-based environments - supported by trusted peer workers - can successfully reach individuals who may not engage with traditional health services. This model is particularly relevant for resource-poor settings, where health infrastructure, clinic accessibility, and trust in formal institutions may be limited. Implementing low-threshold, mobile vaccination strategies in partnership with community-led organisations can reduce barriers related to cost, stigma, geography, and documentation requirements.

Limitations

Mpox vaccination has had an exemption from AIR data entry whereby it is not mandatory to record as it may identify someone as MSM or at risk on their health record. A key limitation of this study was the uncertainty surrounding people who were unmatched on AIR. Whilst we assume this reflects their lack of integration into the healthcare system, this could, in some cases, be a result of incomplete or incorrect information recorded on the Jynneos consent forms, altering personal data due to the concern regarding stigma potentially associated with having a record of mpox vaccine, or simply internet connectivity issues at an SOPV. In fact, participants were pro-actively informed that they don’t need to use their real name or date of birth, and no other identifying details were mandatory. Participants with long names or inaccurately transcribed Medicare numbers were more likely to remain unmatched, potentially leading to underestimation of vaccine uptake and other data points that we retrieved from AIR. This may have introduced information or selection biases: participants who’s data was incorrect or who didn’t’ have an AIR record, respectively, may have actually received two doses, but their vaccination record appeared incomplete. Those biases likely skew results toward showing higher completion and better linkage for KRC's fixed-site participants. As such, our findings are more representative for AIR-matched participants than of SOPV attendees overall who may have avoided AIR registration.

Moreover, 22% of participants who were eligible to receive an mpox vaccination at SOPVs declined this offer and we didn’t collect characteristics of these participants. Additional 15% didn’t get their mpox vaccine administered when deemed ineligible by the nurses, or due to change of mind and we didn’t record any data on the underlyin reasons. Reasons for vaccine refusal were not recorded either. The decision not to explore this further arose from a deliberate decision to prioritise client comfort and maintain a non-judgmental environment in SOPV settings, where introducing discussions about vaccination beliefs could have compromised trust and engagement. Refusals were recorded only when clients explicitly stated they did not wish to be vaccinated, and these decisions were not explored further. People who were unable to receive vaccination were recorded as a separate category. The circumstances which lead to engagements being recorded as unable to receive vaccine were, for instance, language barriers preventing informed consent, or intoxication due to alcohol or other drugs. Having received two doses as a reason for not being eligible was also recorded, but due to repeat attendances, it was unclear whether these people had been reached by mpox vaccination outreach at SOPV previously, or whether they had received their vaccine elsewhere. Additional participants who were referred for mpox vaccination to the nurse onsite at SOPV didn’t complete their vaccination on that occasion following nurse-led screening (about 12% of those referred), particularly when two doses were identified on AIR, when the time since last mpox vaccine was less than four weeks, when they disclosed having had mpox recently or small pox in the past, or when they decided they didn’t want to proceed with the vaccination.

While our study demonstrates the acceptability, feasibility, and vaccination outcomes pertaining to mpox vaccination outreach at SOPVs, the study hasn’t been designed to assess the effectiveness of the mpox vaccine on mpox transmission rates. Further modelling studies may attempt to explore the contribution of SOPV outreach to the decreasing trajectory of mpox notifications in NSW from December 2024 onwards.

Conclusions

Our study suggests that an SOPV-based model of care, particularly when done in collaboration between sexual health clinicians and LGBTQI+ organisations is feasible, acceptable, and promising in reaching populations at risk who may not engage with conventional sexual health services and campaigns. Funding models that circumnavigate traditional geographic and local health service barriers should be considered during outbreaks, particularly when there is an opportunity to build on established rapport that LGBTQI+ organisations or other health outreach services may have within the communities at risk. Further models of care may be explored in these settings beyond vaccination, such as testing for sexually transmissible infections or nurse-led pre-exposure prophylaxis to HIV.

Abbreviations

AIR

Australian Immunisation Register

ACON

AIDS Council of New South Wales (now a community HIV and LGBTQ+ health organisation)

KRC

Kirketon Road Centre

MSM

Men who have sex with men

NSW

New South Wales

SOPV

Sex–on–Premises Venue

Authors’ contributions

AD, NC, MV, JvM, BP, WM, and PR designed the program reported in this study. AD, JvM, and NC contributed to data collection. PR, JK, AD, NCH and VB designed the data audit. VB, JvM, and SC conducted data analysis. VB drafted the manuscript and all co-authors (AD, NC, MV, JvM, BP, WM, BP, SCH, IA, BT, JK) made substantial contributions to it and reviewed the final version.

Funding

This work was supported from KRC’s and ACON’s internal resources. This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

Data availability

The datasets generated and/or analysed during the current study are not publicly available due to NSW Health policies regarding transfer of individual-level client data. No questionnaire was used in this study; the project used de-identified, routinely collected clinical and administrative data. For access to clinical data used in this study, please contact the first author at [vendula.belackova@health.nsw.gov.au](mailto: vendula.belackova@health.nsw.gov.au) .

Declarations

Ethics approval and consent to participate

The process of retrieving, analysing, and publicising the data was reviewed by Low Negligible Risk Committee of South Eastern Local Health District Low and Negligible Risk Committee on 25 February 2025. The need for consent to participate in the study was waived by the committee in accordance with the NHMRC National Statement (updated 2023) —Sect. 5.1.22, the NHMRC Ethical Considerations in Quality Assurance and Evaluation Activities (2014) guidance and NSW Health Guideline GL2007_020 Human Research Ethics Committees - Quality Improvement and Ethics Review: A Practice Guide for NSW. The study was conducted in accordance with the principles of the Declaration of Helsinki (2013), which underpins the ethical standards referenced above and guides the responsible conduct of research involving human participants and data.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.