Table 1.

Summary of studies describing the types of Online-to-Offline (O2O) models implemented globally and their impact to scale up HIV clinical services

Lead author, country	O2O platform	Intervention	Objectives	Target population / Inclusion criteria	Impact of intervention
Information O2O
Eurosurveillance editorial team, 28 European Union (EU) member States [18]	Mobile-optimized, HIV Testing Site Finder, an online tool listing HIV testing clinics across EU states	Enabled online health seeking populations to search for a nearby (geo-location based) HIV testing site by country, town and area code	To increase HIV status awareness and communicate benefits of HIV testing to reduce late diagnosis in Europe	MSM, TG and other key populations	Approximately 40,000 people visited the test finder, and viewed 74,000 testing sites in close proximity
Stephan, Tanzania [19]	PMTCT website hosting regularly updated PMTCT-related news, resources and publications	Engaged website visitors in comprehensive information and resources on PMTCT	To increase access to information about prevention among healthcare workers and PMTCT stakeholders in Tanzania	PMTCT healthcare workers and stakeholders in Tanzania	Website received 28,400 visits, with 66,463 page views, over 2 years; 30 % of visits were from returning visitors. The majority of visitors from Tanzania (50 %) and from other African countries (16 %)
Promotion O2O
Wilkinson, Australia [20*]	Drama Downunder (DDU) social marketing campaign with digital media advertisement i.e. banners on dating website, promotions via outdoor, and print gay media, supported by a range of campaign material	Established an online, open recruitment cohort of MSM and surveyed at approximate 12-month intervals	To promote HIV/STI testing among men who have sex with men (MSM), and evaluate the impact of DDU on HIV, syphilis, gonorrhea, and chlamydia testing	18 years and above gay and other MSM in Victoria, Australia	High campaign awareness among 242 MSM completing 726 prospective surveys. Post-DDU, gonorrhea test rates increased significantly among HIV-negative MSM.
Solorio, USA [21*]	Social marketing campaign, including radio announcements, a website, zip-code based HIV testing locator, social media outreach, a reminder system using mobile technology, print materials, and a toll-free hotline	A cohort of 50 young Latino immigrant MSM were recruited, exposed to campaign and followed over time	To increase HIV testing among young Latino MSM	Latino immigrant, non-self identified MSM, ages 18–30 years old	Increased HIV testing rates at the mid-campaign follow-up (OR 1.7, 95 % CI0.9–3.4, P= 0.1). Campaign received 68,300 impressions from Facebook viewers. A total of 409 interactions with 324 unique followers/fans were recorded.
Tang, China [22*]	Crowdsourced video and health marketing video to promote first-time HIV testing	Participants recruited online were screened for eligibility, enrolled, and were randomly assigned to either watch the crowdsourced video or the health marketing video	To compare first-time HIV testing rates among MSM and TG individuals who received a crowdsourced or a health marketing HIV test promotion video	MSM and TG	In the crowdsourced intervention arm, 114 of 307 (37%) reported testing for HIV compared with 111 of 317 (35%) in the health marketing arm.
eCounseling O2O
Anand, Thailand [23*]	Web-based communications strategy, including website, targeted marketing and promotions, social media and web message boards for online counseling and referrals, and an online tool ‘Testing Site Near You’ to choose nearest available MSM friendly testing site	MSM recruited online through promotions registered on real-time support platforms. Intervention staff assessed risks, shared HIV-related information, offered individualized counseling, and encouraged MSM to undergo HIV screening and provided referrals	Scale-up early HIV testing and counseling (HTC) and linkage to treatment among MSM	MSM	An estimated 11,120 gay men and other MSM received eCounseling; 8,288 MSM were referred to HTC services; 1,223 to STI testing services; 1,112 MSM living with HIV were advised regarding HIV treatment and 278 MSM were advised on PEP and PrEP. The website engaged 1.69 million viewers, and gained more than 8 million page views.
Rhodes, USA [24*]	Offer social support in informal, interactions within 4 geographically focused social media sites: Adam4Adam, BlackGayChat, Craigslist, and Gay.com	A repeated cross-sectional matched-pair randomized trial design with 2 intervention and 2 comparison communities to test whether HIV testing changed after 12 months of intervention implementation	To promote and increase HIV testing among MSM and TG who use existing social media designed for social and sexual networking	MSM and TG	At posttest, 63.7% of intervention participants reported HIV testing compared with 42.0% of comparison participants, an almost three times (2.9) higher odds of testing (95% confidence interval, 1.8–4.7).
Lampkin, USA [25*]	Passive outreach for delivering STD/HIV prevention services to MSM on Grindr, an all male social networking platform	Educators provided health education and information about available STD/HIV testing, and used a variety of methods to encourage and facilitate users in actualizing referrals	Evaluate outcomes related to online outreach through use of a social networking platform with geolocation features, and impact on STD/HIV prevention and linkage-to care services	MSM	A 14-fold increase in (a 5-year period) the number of MSM reached for counseling and education. 35% of engaged users received some combination of counseling, referrals, testing, treatment, and/or follow-up.
Smith, USA [26*]	Proactive outreach on sexual partner-seeking websites (bathhouses, bookstores, sex parties, Craigslist, and anonymous online hookups)	MSM advertising for bareback sex were contacted by trained black gay man for chats and received HIV testing information, risk reduction strategies, and linkage to HIV/STD testing services	Increase HIV awareness, correct risk perceptions and engagement in HIV testing	African American and other minority MSM, age 18 years above	Of 400 contacts advertising for bareback sex and contacted for chats, 30% received a referral to an STD test, and 43.5% received an HIV test as a result of the BARRE program. 89% felt comfortable with proactive outreach.
Mashru, Canada [27*]	Telemedicine-videoconferencing technology based infectious disease consultation service to remote communities	Telemedicine-based infectious disease consultation service to remote communities suffering with a heavy burden of infectious disease	To address needs for care in infectious diseases in northwestern Ontario, where important gaps in service to First Nations’ communities continue to exist	Remote/First Nations’ communities	191 teleconsultations occurred in one year: 76 initial consultations, 82 follow-up appointments and 33 case conferences.
Integrated O2O
Anand, Thailand [28*]	HIV educational and counseling website, tailored social media PrEP promotions, real-time PrEP eCounseling, free online booking system, auto-generated site- and service-specific e-tickets and Quick Response (QR) codes, collaboration with four private, public and CBOs sites	MSM and TG received eCounseling, counsellors conducted risk assessment, introduced them to PrEP and HIV testing services. Participants prioritized their preferred site/service, completed bookings, and received an e-ticket with a QR code. Participants checked-in at the clinic site and staff scanned the QR code	To increase HIV testing and PrEP uptake among high-risk MSM and TG	MSM and TG	Reached 272,568 people online via the PrEP O2O promotions. 425 MSM and TG received eCounseling and e-tickets. 325 (76.5%) MSM and TG checked-in at clinics and received HIV testing. Nine (2.8%) were diagnosed HIV-positive. Of 316 HIV-negative MSM and TG, 168 (53.2%) started PrEP.
Gilbert, Canada [29, 30**]	GetCheckedOnline (GCO), a comprehensive web-based testing service integrated with six sexual health sites for chlamydia, gonorrhea, syphilis, HIV, and HCV testing	Online visitors to the website created an account, completed risk assessment, created and printed a laboratory form, submited specimens, and received results	To increase testing for sexually transmitted and blood-borne infections (STBBIs), reach high-prevalence populations facing testing barriers, and increase clinical STI service capacity	MSM, youth and rural populations	868 created accounts, 590 (68%) completed risk assessments, and 434 (50%) printed and received lab forms. Of those who printed lab forms, 318 (73.2%) submitted specimens. 96 (30.2%) tested more than once and 10 (3.1%) had a positive STI diagnosis
Polilli, Italy [31**]	A Web-based tool with a region wide deployment, information on STIs (HIV, hepatitis B and C, and syphilis), a structured questionnaire called “risk calculator” to assess one’s own risk behaviors and direct booking of their test at one of six sites throughout the region	Users were invited to assess risk behaviors using “risk calculator”, users scoring a moderate or high risk) were encouraged to anonymously (using nickname or fantasy name) make booking for free testing at any of the six linked sites	To recruit persons at high risk of HIV and other STIs and increase HIV/STI screening and linkage to care	High-risk MSM, PWIDs, female, male	About 6,000 users visited the website; >5,000 went through the “risk calculator” and nearly 3,500 booked their testing. Among them, 3,046 (87%) individuals presented for their testing. An overall 7% of unaware STIs, including 0.92% of HIV infections, were diagnosed.
Anand, Thailand [32*]	Electronic health record system (EHR) system to enable online consent, knowledge assessment, appointment scheduling, e-counselling, secure access to laboratory results, automated appointment reminders and personalised messaging, and fast-track access to HIV treatment providers (via online registration code)	Participants were enrolled online based on their preference into one of three EHR-supported arms: (1) private clinic-based HIV testing and counselling (HTC); (2) online pretest counselling and private clinic-based HIV testing (hybrid); and (3) online supervised HIV self-testing and counselling (eHTC)	To engage high-risk MSM and TG in online HIV prevention and treatment cascades	MSM and TG	A total of 489 MSM and TG were assessed for their risk, of whom 186 (38%) enrolled into the study. Of the enrolled participants, 89, 72 and 25 chose to join the HTC, hybrid and eHTC arms. HIV prevalence was highest among participants in the eHTC arm (16% vs 1.4% vs 2.2%, P=0.01).

MSM, men who have sex with men; TG, transgender women; PWIDs, people who inject drugs; FSWs, female sex workers; HIV, human immunodeficiency virus; HCV, hepatitis C virus; STDs, sexually transmitted diseases; STIs, sexually transmitted infections; PMTCT, prevention of mother-to-child transmission of HIV; HTC, HIV testing and counseling; CBOs, community-based organizations; PrEP, pre-exposure prophylaxis; PEP, post-exposure prophylaxis.