Preferences for STI and cancer vaccines in the US and in China

Abstract

Objectives:

This study assessed preferences for hypothetical vaccines for children in two large vaccine markets according to how the vaccine-preventable disease is transmitted via a discrete choice experiment (DCE).

Methods:

Surveys in China (N=1,350) and the US (N=1,413) were conducted April-May 2021. The DCE included attributes of cost, age at vaccination, transmission mode of the vaccine-preventable disease, and whether the vaccine prevents cancer. Preference utilities were modeled in a Bayesian, multinomial logistic regression model, and respondents were grouped by vaccine preference classification through a latent class analysis (LCA).

Results:

Individuals favored vaccines against diseases with transmission modes other than sexual transmission (vaccine for STI vs airborne disease, in the US: OR: 0.71, 95% Credible Interval (CrI): 0.64, 0.78; in China: 0.76, 95% CrI: 0.69, 0.84). The LCA revealed six classes: vaccine rejecters (19% in the US and 8% in China), careful deciders (18% and 17%), preferring cancer vaccination (20% and 19%), preferring vaccinating children at older ages (10% and 11%), preferring vaccinating older ages, but indifferent about cancer vaccines (23% and 25%), and preferring vaccinating children at younger ages (10% and 19%). Vaccine rejection was higher by age in the US, versus more vaccine rejection among those 18–24 and ≥64 years in China.

Conclusion:

The public had strong preferences against giving their child an STI vaccine, and the class preferring a cancer vaccine was less accepting of an STI vaccine. Overall, this study points to the need for more education about how some STI vaccines could also prevent cancers.

Précis:

Parents have strong preferences against STI vaccines for their children in the US and in China.

INTRODUCTION

In 1974, the World Health Organization recommended that countries publicly fund four vaccines: Bacillus Calmette-Guérin, diphtheria-tetanus-pertussis, polio, and measles vaccines. Since 2004, this recommendation has expanded to include six more vaccines (hepatitis B, Haemophilus influenzae type b, pneumococcal conjugate, rotavirus, rubella, and human papillomavirus vaccines) that prevent acute and chronic diseases encompassing sexually transmitted (STI), bloodborne, and respiratory infections.¹

Each year, over 2.7 million individuals die from acute diseases caused by common vaccine-preventable diseases (VPDs), and 762,000 die from cancers secondary to viral hepatitis and human papillomavirus (HPV).² A majority of these deaths occur in low- and middle-income countries (LMICs), and the existing paradigm is that these deaths, along with the hundreds of millions of cases of VPDs, arise due to the lack of vaccine access for families in these countries.^3,4 Recently though, the US has seen large outbreaks of VPDs for which vaccines have been readily available for decades such as pertussis^5–7 and measles^5,8. The voluntary choice not to vaccinate is especially seen in the wealthier and more educated sectors of the population, whereas outbreaks of VPDs in middle-income countries like China (such as a large mumps outbreak in 2011–2012)⁹ is due to lack of access to vaccines. However, middle income countries are not immune to the consequences of vaccine hesitancy; after the dissolution of the Soviet Union, diphtheria-tetanus-pertussis (DTP) uptake fell as parents became suspicious of the vaccine, and a large outbreak of more than 50,000 cases of diphtheria spread throughout eastern Europe.¹⁰ A study in 5 LMICs, including China, found substantial evidence of vaccine hesitancy, particularly over concerns about safety and newer vaccines.¹¹ Currently, there are still large outbreaks of vaccine-preventable diseases in China – for example, over 30,000 cases of pertussis and rubella were reported in China in 2019; in the US, there was also a high number of pertussis cases, with 15,609 reported in 2018.¹²

Since 2000, the US has licensed ten new vaccines,¹³ but research on vaccine hesitancy has not kept pace with vaccine development. The faltering rollout of the HPV vaccine in the US is a cautionary tale on how not to inform the public about a vaccine. Prior to vaccine introduction, awareness of HPV was low.¹⁴ The Advisory Committee on Immunization Practices (ACIP) published its first set of recommendations in 2006; recommendations for routine use in males did not occur until 2011.^15,16 Although the HPV vaccine protects against cervical, anal, oropharyngeal and other cancers, early recommendations did not emphasize prevention of cancer as much as later recommendations.^15,17 Programs that have attempted to promote HPV vaccination since its introduction in the US have met with mixed success.¹⁸ In contrast, the hepatitis B vaccine—which protects against an infection spread not only through vertical transmission but also through injection drug use or sexual intercourse—has not had such a pushback from the public, likely due to being on the pediatric vaccination schedule and being marketed as a product that protects against the development of chronic infection.¹⁹ However, some researchers have argued that “desexualizing” a vaccine could have inadvertent consequences in other areas of public health, like reducing opportunities for health educators to communicate about safe sex practices.²⁰ A vaccine’s period of adoption into the national immunization program is a critical window for shaping public discourse about and uptake of the vaccine. As more vaccines are formulated, determination of how best to promote these vaccines to the public will become critical. Moreover, in China, the national government has set a goal of eliminating cervical cancer by 2047, and in response local governments are rapidly launching HPV vaccination programs targeting younger females.²¹

Multiple STI vaccines are currently in the clinical trial phase of development, with the most advanced candidates (targeting HSV-2) projected to be licensed within ten years.²² The future introduction of STI and other vaccines for adolescents into national immunization schedules will have to deal with a population of parents who may be skeptical about newer vaccines and for STI vaccines in particular. It will be important to understand how STI vaccines could be efficiently rolled out with parental preferences taken into consideration. However, these preferences may vary across country. With samples taken from the US and China, the most populous high high-income and middle- income countries, respectively, this study 1) used a discrete choice experiment (DCE) to assess preferences for vaccines according to how the disease, against which the vaccine protects, is transmitted; and 2) classified individuals into preference classes using an exploratory latent class analysis (LCA). We hypothesized that there would be a strong dispreference for STI vaccines.

METHODS

Study population

This cross-sectional study enrolled both parent and non-parent adults ≥18 years old in China and the US. Data collection occurred in April and May 2021. Participants were recruited for the internet-based survey by the research firm Dynata through social media and advertisements. Each wave used quota sampling to ensure that the numbers of participants invited were roughly proportional to the age/gender distribution of the adult population.

We aimed to obtain a sample of 1,500 adult parents and non-parents from each country. This sample size was based on considerations for the discrete choice experiment and the proportion in the sample that were parents (to ensure that we had enough sample for sensitivity analyses only including parents). In other research based on national panels, it has been found that about 63% of panelists are parents.²³ The sample size of parents within this survey (63% of 1,500 is 945) was considered an adequate sample for statistical purposes. There is no standard methodology to calculate sample size for conjoint analysis studies such as DCEs,²⁴ but one formula for sample size is the following:²⁵

$$N>\frac{\mathrm{1,000}\times \left(largestnumberofattributelevels\right)}{\left(numberofchoicetasks\right)\times \left(numberofalternatives\right)}$$

This led to a simple random sample of 500 with 4 attribute levels, 4 choice tasks, and 2 alternatives. Our sample, of approximately 1,500 in each country (or approximately 945 parents in each country), was sufficient for the purposes of the DCE.

Attributes and study design

The list of attributes is found in Table 1. Based on a review of the contrasts between HPV and hepatitis B vaccines, we selected the following attributes: cost, age at vaccine administration, transmission mode for disease that vaccine protects against, and whether the vaccine prevents cancer, and also allowed for an opt out (i.e., parents deciding not to vaccinate their child). Cost distributions were based on realistic values from the Vaccines For Children price list²⁶ and vaccine costs within China²⁷. For ease of interpretation, we converted Chinese renminbi (RMB) to US dollars using a purchasing power parity currency conversion of 4.186 ²⁸. The ages at vaccination administration were chosen based on ages at which vaccines are commonly administered in the schedule recommended by the US²⁹ and China Experts Advisory Committee on Immunization Practices³⁰. The transmission modes spanned those of diseases that are currently vaccine preventable (e.g., pertussis and measles being airborne/respiratory, hepatitis A being foodborne, Japanese encephalitis being mosquito-borne, and hepatitis B and HPV being sexually transmitted).

Table 1.

List of attributes and attribute levels in a discrete choice experiment of vaccination preferences.

Attribute	Attribute levels
Age of vaccine administration	2 years 6 years 12 years 15 years
Transmission mode for vaccine-preventable disease	Airborne Foodborne Mosquito-borne Sexually transmitted
Vaccine prevents cancer	Yes No
Cost	50 USD/RMB 100 USD/RMB 200 USD/RMB 400 USD/RMB

We used a fractional factorial design and allowed respondents to opt out of the two choice profiles. Each respondent answered four different choice sets with the prompt: “In the following questions you will be presented with a table detailing two different vaccines for the same disease, Vaccine A and Vaccine B. Choose the vaccine that you would prefer be administered to your child”. Before showing participants the choice profiles, we explained each attribute separately. After answering the questions, participants were asked how confident they were in responding to the DCE questions. We also collected standard demographic information from each participant. The surveys are available at: https://doi.org/10.6084/m9.figshare.16632343.v1.

Covariates

Our demographic variables of interest were age, gender, education, and parenthood. For parenthood, we singled out parents of daughters 5–17 years old to better understand the potential for gendered issues of STI vaccines. Within the US, we also collected information on race/ethnicity, religion, and political affiliation.

Statistical analysis

We conducted a Bayesian analysis of the discrete choice experiment, with noninformative priors.³¹ We specified a multinomial logistic regression model with the dataset situated as three observations per person (the choice of vaccine A, B, or to opt out). This model yields odds ratios and 95% credibility intervals (CrI). We conducted a number of sensitivity analyses, including limiting the sample to those who indicated that they were confident in their responses and to those who were parents. Our main model includes cost of vaccine as a continuous variable, but supplementary analyses include it as a categorical variable following the original design of the conjoint analysis. These sensitivity analyses did not produce substantially different results (see Supplementary Tables 2 and 3). Our descriptive analyses are weighted, with raked weights³² developed based on age, gender, and region of country for both countries (and additionally race/ethnicity for the US).

Subsequently, we conducted a latent class analysis to classify individuals based on their preference characteristics; an individual is assigned to the class with the highest posterior probability. Our choice in the number of classes was based on model fit and interpretability of results.³³ We compared classes across demographic characteristics across the estimated classes using Rao-Scott chi-square tests. We named the preference classes based on the most preferred attribute levels in each class.

Ethical approval

The study protocol was reviewed by the University of Michigan Health Sciences and Behavioral Sciences Review Board (#HUM00193501) and the Fudan University School of Public Health Ethical Review Committee (IRB#2021–03-0887). Participants read an electronic informed consent form prior and had to click “I agree” before answering any questions.

RESULTS

In total, the online questionnaire database captured responses from 2,371 individuals in the US and 1,830 individuals in China. After excluding those who did not agree to the informed consent, we had a final sample of 1413 from the US and 1350 from China. The distribution of demographic variables is shown in Table 2. The US and Chinese samples were relatively comparable in the proportion of individuals with a high school education or less (19% in US, 20% in China), and the proportion with a Bachelor’s degree (52% in the US, 53% in China). In both countries, a small proportion were parents of a daughter 5–17 years old: 14% in the US and 11% in China.

Table 2.

Distribution of sociodemographic variables across US and China samples, April-May 2021.

		US Sample (N=1413)	Chinese sample (N=1350)
Age	18–24	273 (12%)	239 (11%)
	25–34	317 (17%)	367 (21%)
	35–44	320 (16%)	334 (18%)
	45–54	130 (16%)	207 (22%)
	55–65	147 (17%)	116 (15%)
	≥64	226 (22%)	87 (14%)
Gender	Female	763 (51%)	681 (49%)
	Male	650 (49%)	669 (51%)
Educational attainment	≤High school	313 (19%)	184 (20%)
	Vocational school or associate’s degree	417 (29%)	360 (27%)
	Bachelor’s degree	683 (52%)	806 (53%)
Parent of daughter 5–17 years old	No	1190 (86%)	1164 (89%)
	Yes	223 (14%)	186 (11%)
Race/ ethnicity	Non-Hispanic Black	195 (12%)	--
	Non-Hispanic white	944 (71%)	--
	Hispanic	128 (7%)	--
	Other	146 (11%)	--
Religion	None	398 (27%)	--
	Catholic	232 (17%)	--
	Evangelical Protestant	337 (23%)	--
	Mainline Protestant	128 (11%)	--
	Jewish	54 (4%)	--
	Other	264 (17%)	--
Political affiliation	Democrat	597 (40%)	--
	Independent	415 (30%)	--
	Republican	401 (30%)	--

Figure 1 graphically displays results from the discrete choice experiment (which is also presented, along with willingness to pay estimates, within Supplementary Table 1). Overall, individuals in the US and in China preferred other vaccines over STI vaccines (reference level: vaccine for airborne disease, in the US: OR: 0.71, 95% CrI: 0.64, 0.78; in China: 0.76, 95% CrI: 0.69, 0.84). In the US, individuals expressed stronger preference for a vaccine protecting against cancer (OR: 1.10, 95% CrI: 1.04, 1.17), whereas in China the opposite association was observed (OR: 0.87, 95% CrI: 0.83, 0.92). There were no major differences in preferences for the age at vaccination administration in China or the US.

Figure. 1.

Preferences for pediatric vaccines of various characteristics in China (n=1,350) and the US (n=1,413); results are obtained from a Bayesian multinomial logistic regression model.

Model fit for different numbers of classes are shown in Supplementary Table 4 for the US and Supplementary Table 5 for China. We chose 6 classes for each country as a balance between increased fit as the number of classes increased with interpretability of the results (Supplemental Table 6 show alternative results from a 5-class LCA). The composition of each class varies slightly between countries, but we were able to describe classes within each country in a similar fashion (see Supplementary Tables 7 and 8). Vaccine rejecters (19% in the US and 8% in China) were those who tended to opt out of the DCE. Another class included those we describe as careful deciders (18% in the US and 17% in China), meaning that one attribute in particular did not drive their decision making. Those with strong preferences for a cancer vaccine made up 20% of the US sample, and 19% of the China sample. There were individuals grouped into classes based on whether they preferred vaccinating their child at younger ages (10% in the US, 19% in China), at older ages (10% in the US, 11% in China) or at older ages, but being indifferent about cancer vaccines (23% in the US and 25% in China). Notably, the class with preferences for vaccinating at younger ages also preferred not receiving a cancer vaccine. Overall, vaccines for an STI were strongly not preferred except in the careful decider class and the class preferring cancer vaccines.

We describe how the different classes vary by demographic composition in Table 3 (for the US) and Table 4 (for China). The largest trends were observed in differences between being classified as a vaccine rejector or not. For the US there was a strong monotonic relationship between being a vaccine rejector and age, with 13% of those 18–24 years old rejecting vaccines, versus 30% in those ≥64 years (P<0.0001). In China, this was a U-shaped relationship, with the lowest levels of classification as a vaccine rejector in those 35–44 (4%), but classification as a vaccine rejector relatively high for those 18–24 and ≥64 (P<0.0001). In the US, there were not significant differences in class assignment by gender, education, and whether the participant was a parent of a daughter 5–17 years old. In China, there was a significant difference (P=0.0064), with lower numbers in the vaccine rejection class who were parents of daughters (4%) compared to those who were not (9%). In the US, we also examined differences across race/ethnicity, religion, and political affiliation. Across race/ethnicity, the highest proportion in the vaccine rejection group was found among non-Hispanic white Americans (23%) and was relatively low among Hispanic Americans (12%). By political affiliation, vaccine rejection was highest among independents (28%) and lowest among Democrats (15%). There were no significant differences by religion.

Table 3.

Demographic characteristics by pediatric vaccine preference from a latent class analysis, US, April-May 2021.

		Vaccine rejecters	Prefer cancer vaccines	Prefer vaccinating older ages	Careful deciders	Prefer vaccinating younger ages	Prefer vaccinating older ages, indifferent about cancer vaccines
Age P<0.0001	18–24	13%	20%	12%	21%	10%	23%
	25–34	14%	23%	11%	19%	11%	23%
	35–44	14%	21%	11%	19%	11%	24%
	45–54	26%	18%	9%	16%	9%	21%
	55–65	28%	18%	10%	16%	8%	20%
	≥64	30%	16%	9%	15%	9%	20%
Gender P=0.2466	Female	23%	20%	10%	17%	9%	21%
	Male	20%	19%	10%	18%	10%	23%
Educational attainment P=0.1210	≤High school	24%	18%	9%	18%	10%	22%
	Vocational school or associate's degree	23%	18%	10%	19%	9%	21%
	Bachelor’s degree	20%	21%	11%	17%	10%	22%
Parent of daughter 5–17 years old P=0.3086	No	22%	19%	10%	17%	10%	22%
	Yes	18%	20%	10%	19%	11%	23%
Race/ ethnicity P=0.0314	Non-Hispanic Black	18%	20%	11%	19%	10%	22%
	Non-Hispanic white	23%	19%	10%	17%	10%	21%
	Hispanic	12%	21%	11%	20%	11%	26%
	Other	20%	19%	10%	17%	10%	24%
Religion P=0.8455	None	22%	21%	10%	16%	9%	21%
	Catholic	21%	19%	10%	17%	10%	23%
	Evangelical Protestant	20%	18%	11%	19%	10%	22%
	Mainline Protestant	26%	20%	9%	17%	9%	19%
	Jewish	19%	19%	14%	19%	8%	21%
	Other	22%	19%	9%	18%	10%	23%
Political affiliation P<0.0001	Democrat	15%	22%	11%	18%	10%	24%
	Independent	28%	17%	10%	16%	9%	20%
	Republican	24%	18%	9%	19%	10%	21%

Note:

P-values from Rao-Scott chi-square tests.

Table 4.

Demographic characteristics by pediatric vaccine preference from a latent class analysis, China, April-May 2021.

		Vaccine rejecters	Prefer cancer vaccines	Prefer vaccinating older ages	Careful deciders	Prefer vaccinating younger ages	Prefer vaccinating older ages, indifferent about cancer vaccines
Age P<0.0001	18–24	13%	20%	11%	17%	16%	23%
	25–34	8%	20%	11%	16%	18%	27%
	35–44	4%	19%	11%	20%	21%	26%
	45–54	5%	21%	12%	18%	20%	25%
	55–65	10%	19%	12%	16%	20%	22%
	≥64	14%	18%	11%	15%	17%	25%
Gender P=0.1652	Female	7%	20%	12%	17%	19%	25%
	Male	10%	19%	11%	17%	19%	25%
Educational attainment P=0.0945	≤High school	11%	20%	9%	17%	19%	25%
	Vocational school or associate’s degree	9%	20%	13%	16%	18%	24%
	Bachelor’s degree	7%	19%	11%	18%	19%	26%
Parent of daughter 5–17 years old P=0.0117	No	9%	20%	11%	17%	19%	25%
	Yes	4%	20%	12%	18%	19%	27%

Note:

P-values from Rao-Scott chi-square tests.

DISCUSSION

The introduction of the HPV vaccine in the US and in China has led to a need for new communication techniques and framing for parents compared to other childhood vaccines. Following the HPV vaccine, numerous STI vaccine candidates will likely achieve licensing in the foreseeable future,³⁴ and this study highlights potential pitfalls to STI vaccine promotion. Using internet-based samples in China and the US, we sought to understand preferences in the general population for STI vs non-STI vaccines using a discrete choice experiment. We found that individuals had a weaker preference for a vaccine against sexually transmitted infection. Overall, our study highlights some challenges in introducing an STI vaccine into a population in the presence of strong preferences against STI vaccines.

We found somewhat similar results for China and the US in terms of opt-out, age, and transmission mode preferences. However, there were opposite trends for preferences for a cancer vaccine and cost of the vaccine. In the US there was a preference for a cancer vaccine, whereas in China there was a preference for a non-cancer vaccine. We will note that this could be due to low knowledge of specific cancer vaccines, like the HPV vaccine in China. Knowledge about the vaccine and its related infection was greatly related to vaccination choices in a previous DCE of HPV vaccination preferences in Zhejiang province, China.³⁵ Hepatitis B vaccines have been publicly funded in China since 2002,³⁰ but the HPV vaccine has only recently been introduced into the private market in China; this lack of long-term use of multiple anti-cancer vaccines may indicate a lack of familiarity with these vaccines in China and accordingly less strong preferences for them. We also found that in the US, as expected, there was a dispreference for a more costly vaccine, whereas in China the opposite association was found. Similar trends were found in previous studies.^36,37 Sensitivity analyses within a previous paper suggested that trends in the overall population were being driven by higher income individuals valuing higher cost vaccines (perhaps out of a conflation between cost and quality), whereas individuals of lower socioeconomic status had dispreferences for higher cost vaccines, as expected.³⁶

We found a substantial dispreference for STI vaccines, with little difference across comparisons with other vaccines (for airborne, mosquito-borne, or foodborne illnesses). Within the US, there has been stated concern that vaccinating adolescents against an STI could negatively influence sexual behaviors,³⁸ although empirical evidence has shown this to be an unfounded concern.³⁹ A previous qualitative study also noted that for some parents, knowing that the HPV vaccine protected against an STI was important for their decision-making, but for other parents it was not as important.⁴⁰ It is also possible that preferences differ by gender of the child, and we note that only about 1 in 3 HPV vaccination programs worldwide vaccinate both girls and boys.⁴¹ As vaccine candidates for HSV-2, chlamydia, and other STIs progress through clinical trial development, it will be important for industry and public health stakeholders to strategize about how to effectively increase vaccine uptake. There are other possible reasons for differences in preferences across transmission modality; it is possible that the COVID-19 pandemic has increased the relative salience of vaccines for airborne transmitted infections. It is also possible that the lower preference for STI vaccines could be due to beliefs that the infection could be prevented through other means, like safer sex practices. However, it is also likely that many vaccine-preventable illnesses could also be prevented through non-pharmaceutical interventions, including safer food preparation and mask wearing.

In our latent class analyses, we found similar classifications for China and the US, although the proportions varied slightly. For instance, there were more vaccine rejecters in the US (19%) than in China (8%). Direct comparisons of vaccine attitudes across different countries are limited in the scientific literature. However, a recent global study actually found higher proportions of individuals in the US believing that vaccines are effective, important and safe, than in China.⁴² Attitudes towards vaccines in China may be shaped by some recent safety and quality scandals.⁴³ On the other hand, coverage of mandatory pediatric vaccines in China is relatively high.⁴⁴ In line with the results of our study, this may suggest individuals in China may have concerns about vaccines but still are willing to obtain vaccines for their children or may be strongly influenced by the presence of vaccine mandates.

There were similar proportions of individuals in the class preferring cancer vaccines in China (19%) and in the US (20%). Interestingly for both China and the US, individuals in this class were more willing to consider STI vaccines than other classes. Accordingly, pushing forward a message that STI vaccines, like HPV and hepatitis B, also protect against cancer could be motivating for vaccine acceptance, but might be less impactful among individuals of other vaccine preference classes. In the initial roll-out of the vaccine, there was a large backlash over sex-related concerns. Succinct messages that frame HPV vaccine as both an STI and a cancer vaccine could be useful and be in line with public health goals to promote healthy sexual activity and to reduce rates of HPV related cancer.^20,45 In fact, it is important to highlight that clear communication between parents and vaccination providers is essential to increase uptake of the vaccine.⁴⁶

Within the US, age, race/ethnicity, and political affiliation were all associated with LCA classification. For all these, the most substantial differentiation was between vaccine rejecters and other categories, with little difference across the other four categories. This could indicate that the relationship between demographic status and vaccine attitudes is more tied to whether an individual accepts or rejects a vaccine, but not on shades of how they accept vaccines or what specific vaccines they prefer. Previous studies have also shown vaccine hesitancy to be relatively high in white Americans, with low levels of vaccination in Black Americans more tied to access and affordability issues than hesitancy.⁴⁷ Similarly, a study in Australia found lowest vaccination coverage in the most affluent areas.⁴⁸ Although some studies have identified some more concerns among Black Americans about side effects,⁴⁹ much of this can be tied to racial discrimination.⁵⁰ We also note that we did not find a difference in class assignment across religion within the US. Previous studies have found this relationship⁵¹ (although another study actually found the reverse association)⁵². Discrepancies across previous studies and our studies in the relationship between religion and vaccination could be due to differences in location, time, or how variables were assessed.

Fewer studies in China have studied vaccine hesitancy patterns. A recent scoping review of this literature found that most studies position vaccine hesitancy as a result of medical misconduct or vaccine safety concerns⁵³ China does have high vaccination rates, although coverage for mandatory vaccines is higher than for voluntary vaccines,⁴⁴ and some vaccines, like rotavirus, Hib, pneumococcal, and HPV vaccines are voluntary in China and thus have low coverage.

Among LMICs, several populous countries, including Turkmenistan, Zambia, Uzbekistan, Mexico, and Rwanda, are reported to have over 90% first dose coverage of the HPV vaccine.⁴¹ Evaluation of projects in LMICs have highlighted the needs to integrate HPV vaccination with other community health programs, including vaccination, to distribute the vaccine at schools and other locations, and to involve multiple stakeholders.^54,55 The examples speak to the ability to successfully promote STI vaccines in diverse settings. Vaccination coverage could also be increased through vaccine mandates.⁵⁶

Strengths and limitations

There are several limitations to this study. It is an opt-in study, such that our sample is not probability based and is biased towards those with internet access. The probability of internet access also varies between the countries. Our results therefore need to be explored in more robust samples. We note that our sample is more educated in the general population – for example, in our study in China, 27% had a two-year post-secondary degree, and 53% had a Bachelor’s degree. The National Bureau of Statistics of China estimates these numbers to be 36% and 18%, respectively, for adults 25–34 in 2020.⁵⁷ The US Census estimates that 35% of adults in 2020 had a Bachelor’s degree, and 10% had an associate’s degree,⁵⁸ compared to 52% and 29%, respectively, in our sample. We purposefully asked about preferences for broad groupings of vaccine-preventable disease by transmission modality, but we acknowledge that individuals could have varied preferences for vaccines within group (e.g., for an influenza vs COVID-19 vaccine, or for an HIV vs gonorrhea vaccine). A strength is the similar study design in the US and in China, which results in us being able to make direct comparisons across countries.

Conclusions

In this discrete choice experiment, jointly conducted in the US and in China, we found that the public, when asked about childhood vaccines, had relatively low preferences for STI vaccines vs vaccines for airborne, foodborne, or mosquito-borne infections. With an LCA, the class preferring a cancer vaccine did not accept an STI vaccine. Overall, this study points to the need for more education about how some STI vaccines can also prevent cancers, and that doctors should be open in their communication with parents.

Highlights.

• Countries have had mixed success rolling out vaccines for sexually transmitted infections. For example, HPV vaccination lags behind Hepatitis B vaccination.

• Individuals in the US and in China had consistently strong dispreferences for STI vaccines, although the two countries varied in terms of what proportion and what groups would reject vaccines altogether.

• Roll-out of future STI vaccines should also consider preferences for when the vaccine be administered and what chronic diseases the vaccine prevents.