Abstract
In April 2021, the US paused Janssen (J&J) COVID-19 vaccination because of reported blood clots post vaccination. This paper explores how vaccine decision-making--receiving a J&J vaccine right away vs waiting for a Pfizer vaccine--changed during the pause. In an opt-in internet-based survey April 2021 with 915 participants, 37 % were not vaccinated. Of these, 18 % would accept a J&J vaccine, 5 % would wait 1 month for a Pfizer vaccine, 25 % would wait 3 months, and 52 % would not want any vaccine. Among the unvaccinated, 56 % had heard of blood clots; 61 % of these did not want any vaccine, compared to 41 % of those who had not heard of blood clots. Moreover, among those vaccine hesitant in general, 11 % would still obtain a J&J vaccine if offered right away. These findings may suggest spillover of brand-specific adverse event concerns to the vaccine product as a whole.
Keywords: COVID-19, Vaccines, Adverse reactions, Risk perceptions
Introduction
Since December 2020, the COVID-19 vaccine has been available in the US. Maintaining high vaccination coverage is a goal of the US government [1]. In the US, there are several brands of the COVID-19 vaccine: Pfizer, Moderna, and Johnson and Johnson (J&J). Based on the brand and its reported side effects, people may have preferences [2]. For example, US residents may be less likely to receive a shot requiring multiple doses [3], and vaccines with more side effects may also be less preferred [4].
On February 27, 2021, the J&J vaccine received emergency use authorization (EUA) from the Food and Drug Administration (FDA). After receiving six reports of cerebral venous sinus thrombosis among J&J vaccine recipients, the Center for Disease Control & Prevention (CDC) and FDA recommended a pause of J&J vaccine use on April 13, 2021. The Advisory Committee on Immunization Practices (ACIP), which had recommended use of the J&J vaccine on February 28, 2021, reaffirmed on April 23, 2021, the continued use of the J&J vaccine [5]. On that same date, the CDC and FDA also issued guidance to resume use of the J&J vaccine, while developing fact sheets which contained information about the risk of blood clots [6].
There are several distinctions of the J&J vaccine – its primary vaccination schedule only requires one dose, and it is an inactivated, and not mRNA vaccine such as the Pfizer and Moderna vaccines. However, there is less information about how a pause in vaccination of a specific brand could affect individual choices on receiving a COVID-19 vaccine in general. To understand vaccine decision-making during the pause, we surveyed US residents in April 2021 and characterized their preferences for obtaining a J&J vaccine vs another vaccine (Pfizer).
Methods
Study population
Survey participants comprised an online, opt-in sample during April 20–28, 2021. Eligibility criteria included being ≥18 years and residing in the US. We excluded individuals who skipped questions in the survey and who took less than 180 s in completing the survey. Detailed information about the survey is available elsewhere [7]. The datasets [8] and the questionnaires [9] are publicly available.
Vaccination status and preferences
The survey asked participants if they had already received a COVID-19 vaccine. If they had not, we asked: “Suppose you were offered an appointment for the Johnson & Johnson (Janssen) vaccine today. You were also told that you could instead get an appointment for a Pfizer vaccine, but it would be one month from now. Assume no other vaccination appointments would be available. Which would you choose?” For those who would wait one month, we asked the same question, switching the time frame to three months. We classified individuals into the following: those who do not want a COVID-19 vaccine; those who are willing to wait 3 months for a Pfizer vaccine; those who are willing to wait 1 month for a Pfizer vaccine; and those who would obtain a J&J vaccine.
Covariates
We considered the following covariates: gender, age, race/ethnicity, education, and vaccine hesitancy. This last measure came from the 10-item adult Vaccine Hesitancy Scale (aVHS), and participant responses were dichotomized to categorize those hesitant and non-hesitant [10]. We also asked participants: “What side effects have you heard about after receiving a COVID-19 vaccine? Select all that apply.” One option was blood clots. From this question we created a dichotomous variable for those who had heard about clots versus those who had not. Participants were then asked “How concerned are you about side effects after receiving a COVID-19 vaccine?” with the options very concerned, somewhat concerned, and not at all concerned.
Statistical analysis
In this exploratory, descriptive analysis, P-values from Rao-Scott chi-square tests compared participants based on their vaccination status (a dichotomous outcome), and timing preferences for receiving a J&J vs Pfizer vaccine, across covariates. All calculations and analyses were run in SAS version 9.4 (SAS Institute, Cary, NC), and analyses were weighted based on US Census results for age, gender, and race/ethnicity [7]. P-values were considered significant if they were less than 0.05.
Ethical approval
The research protocol was reviewed and approved by the University of Michigan Health Sciences and Behavioral Sciences Institutional Review Board (#HUM00180096). Participants read an informed consent form and clicked “I agree to participate in the study” prior to any data collection occurring.
Results
Among the 915 individuals surveyed in April of 2021, 580 (63 %, 95 % confidence interval (CI): 60 %, 66 %) had already been vaccinated (Table 1). Vaccination was higher in males (68 %) than females (58 %) (P = 0.0044), and in older ages (84 % in those ≥65 vs 54 % in those 18–44, P < 0.0001). Among the different racial/ethnic groups, coverage was relatively high in non-Hispanic white (65 %) and Hispanic Americans (63 %), and lower in Non-Hispanic Black (43 %) Americans (P = 0.0073).
Table 1.
Demographic distribution of study participants, along with vaccination status, in the US, April 2021.
| Count (weighted col. %) | Already vaccinated (weighted row %) | P-value | |
|---|---|---|---|
| Overall | 915 | 580 (63 %) | |
| Gender | 0.0044 | ||
| Female | 480 (51 %) | 283 (58 %) | |
| Male | 435 (49 %) | 297 (68 %) | |
| Age | <0.0001 | ||
| 18–44 | 397 (46 %) | 213 (54 %) | |
| 45–64 | 301 (33 %) | 186 (62 %) | |
| ≥65 | 217 (21 %) | 181 (84 %) | |
| Race/ethnicity | 0.0073 | ||
| Hispanic | 78 (9 %) | 47 (63 %) | |
| Non-Hispanic Black | 74 (8 %) | 33 (43 %) | |
| Non-Hispanic white | 693 (74 %) | 453 (65 %) | |
| Other | 70 (9 %) | 47 (66 %) | |
| Education | <0.0001 | ||
| High school or below | 207 (23 %) | 107 (50 %) | |
| College and above | 708 (77 %) | 473 (67 %) |
Among those unvaccinated (N = 335), 18 % (95 % CI: 14 %, 22 %) chose to receive a J&J vaccine in the timing preference question, vs 5 % (95 % CI: 2 %, 7 %) who would wait 1 month, and 25 % (95 % CI: 20 %, 30 %) who would wait 3 months for a Pfizer vaccine; 52 % (47 %, 58 %) did not want a vaccine at all (regardless of brand and timing).
Vaccine timing and brand preferences varied significantly by gender, age, and vaccine hesitancy (Table 2). Women had a higher prevalence of not wanting any vaccine (61 % vs 40 % among males), and not wanting a J&J vaccine (11 % vs 28 % of males). For those who were vaccine hesitant according to the aVHS, 65 % did not want to be vaccinated (vs 17 % of those not hesitant), and less would accept a J&J vaccine (11 % vs 35 %).
Table 2.
COVID-19 vaccination preferences among the unvaccinated (N = 335), during a pause in Johnson & Johnson (J&J) vaccine, April 2021.
| Would get J&J vaccine right away | Willing to wait 1 month for Pfizer vaccine | Willing to wait 3 months for Pfizer vaccine | Does not want any vaccine |
P-valuea | |
|---|---|---|---|---|---|
| Overall | 60 (18 %) | 16 (5 %) | 80 (25 %) | 179 (52 %) | |
| Gender | 0.0002 | ||||
| Female | 21 (11 %) | 10 (5 %) | 43 (23 %) | 123 (61 %) | |
| Male | 39 (28 %) | 6 (4 %) | 37 (27 %) | 56 (40 %) | |
| Age | 0.0207 | ||||
| 18–39 | 41 (22 %) | 9 (5 %) | 48 (27 %) | 86 (46 %) | |
| 40–64 | 13 (12 %) | 6 (5 %) | 30 (26 %) | 66 (57 %) | |
| ≥65 | 6 (16 %) | 1 (3 %) | 2 (5 %) | 27 (76 %) | |
| Race/ethnicity | 0.8249 | ||||
| Hispanic | 8 (25 %) | 2 (8 %) | 6 (20 %) | 15 (47 %) | |
| NH Black | 10 (24 %) | 2 (5 %) | 8 (22 %) | 21 (49 %) | |
| NH white | 42 (18 %) | 11 (4 %) | 54 (23 %) | 133 (55 %) | |
| Other | 0 | 1 (3 %) | 12 (56 %) | 10 (41 %) | |
| Education | 0.4353 | ||||
| High school or below | 20 (19 %) | 5 (6 %) | 20 (21 %) | 55 (54 %) | |
| College and above | 40 (18 %) | 11 (4 %) | 60 (26 %) | 124 (52 %) | |
| Vaccine hesitancy | <0.0001 | ||||
| Hesitant | 29 (11 %) | 11 (5 %) | 44 (19 %) | 163 (65 %) | |
| Not hesitant | 29 (35 %) | 5 (5 %) | 35 (42 %) | 15 (17 %) | |
| Heard about Blood clots | 0.0010 | ||||
| Yes | 22 (12 %) | 9 (4 %) | 42 (23 %) | 121 (61 %) | |
| No | 38 (27 %) | 7 (5 %) | 38 (27 %) | 58 (41 %) |
Notes: NH, non-Hispanic.
Rao-Scott chi-square test, except for race/ethnicity, which is a Fisher’s exact test.
In this study, 56 % (95 % CI: 51 %, 62 %) of unvaccinated individuals had heard of blood clots as an adverse event. The proportion accepting a J&J vaccine were substantially less between those who had heard (12 %) and not heard (27 %) about blood clots, and total vaccine rejection was much higher for those who had heard (61 % vs 41 % who had not heard of blood clots) (P = 0.0010). Additionally, of those who had heard about blood clots, 68 % were very concerned about vaccine side effects; among those who had not heard about blood clots, 39 % were very concerned.
Discussion
In the first few months of the roll-out of the J&J vaccine, six women 18–48 years old, out of 6.8 million doses administered, had blood clots following vaccination [11]. This study provides context in how individuals make decisions about getting vaccinated in circumstances where there is substantial negative news about a vaccine. Although we could not causally link hearing about the pause and specific vaccine attitudes or decisions in this cross-sectional study, we did find a substantial dispreference for the J&J vaccine, with a substantial proportion preferring to wait up to 3 months for a vaccine than to receive the J&J vaccine immediately.
One other study examined population preferences for specific COVID-19 vaccine brands over time [12]. In a study in Canada, Merkley and Loewen found that the population’s hesitancy in receiving the AstraZeneca and J&J vaccines grew between February and April 2021, and that negative perceptions of vaccine safety had a greater marginal effect on AstraZeneca and J&J vaccination over time [12].
This study found that participants would prefer to wait a substantial amount of time to obtain a more preferred vaccine brand even when another vaccine brand was available. This finding has an implication for distribution of scarce resources: research on how vaccine decision-making factors into allocation of pandemic vaccines is still scant [13]. That individuals have stated preferences of waiting for specific vaccines could have epidemiological consequences, as vaccination delays increase the population of susceptible individuals. People may also prefer to wait and see what other people’s experiences are with vaccination [14] in order to choose a product they are more comfortable with.
Several demographic correlates related to preferences for vaccine brand and timing. Women were more likely to not want a COVID-19 vaccine and not want the J&J vaccine. This latter point could be due to news surrounding the J&J pause focusing on women being affected [11]. Another study in Detroit also showed lower acceptance of a COVID-19 in women, particularly when survey participants were given information that the vaccine had more side effects [15]. This could speak to more sensitivity towards perceived side effects among women.
It is possible that hearing about blood clots affected vaccine decisions. Interestingly, those who had heard of blood clots were more likely to reject any COVID-19 vaccine instead of making an informed decision between a J&J vaccine and another vaccine which did not have this vaccine safety signal. It is possible that individuals already with negative attitudes towards vaccines were more likely to pay attention to news. But a finding of increased safety concerns for a specific vaccine brand (also echoed in a previous study [12]) would suggest the need for greater care when making decisions to pause one brand of a product. Individuals may decide to reject the product as a whole instead of choosing another brand. When presented with negative news about vaccines, individuals may be more resilient if they are deferential to authority figures, and have notions of anticipatory regret and social responsibility [16]. This shows that maintaining trust in authority figures and healthcare professionals as well as maintaining public confidence are ways to improve vaccine uptake, and this could be applied to the J&J vaccine.
We also note, that among those who are vaccine hesitant and unvaccinated, 11 % would still accept a J&J vaccine if offered. This finding speaks to the complicated interplay of factors such as acceptance of vaccines and access to health care services [17] when an individual makes a decision to be vaccinated. Accordingly, general hesitancy towards vaccines does not equate with non-vaccination, and individuals may still become vaccinated, particularly when it is convenient to do so (e.g., in this study’s stated scenarios where a J&J vaccine was available right away).
Strengths and limitations
Although this study was eligible to be taken by anyone resident in the US, it may be biased towards certain segments of the population who have internet access and are on social media. Information was self-reported by the participants, and there could be errors from social desirability bias. Our study is a cross-sectional design, and so we could not assess temporality of hearing about blood clots and making vaccine decisions. Individuals vaccine hesitant or with negative attitudes towards vaccines could also overreport side effects. We also did not measure exposure to news sources in this study.
Conclusions
Overall, this study, conducted shortly after the FDA’s recommended pause in J&J vaccinations in the US, found that many individuals would prefer to wait for several months to receive another vaccine, when given the option to receive a J&J vaccine right away. Moreover, hearing about blood clots was correlated with a decision not to receive any COVID-19 vaccine. This finding may suggest spillover of brand-specific adverse event concerns to the vaccine product as a whole.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
Acknowledgements
We appreciate the work of Kaitlyn Akel and Mengdi Ji in cleaning the datasets.
Funding
This project was supported by an award from the National Science Foundation, Division of Social and Economic Sciences (#2027836), and by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health (R01AI158543). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
Data availability
Data are available at: https://doi.org/10.3886/E130422.
References
- 1.US Department of Health and Human Services. Vaccines national strategic plan 2021–2025; 2021.
- 2.Arshad M.S., Hussain I., Mahmood T., Hayat K., Majeed A., Imran I., et al. A national survey to assess the covid-19 vaccine-related conspiracy beliefs, acceptability, preference, and willingness to pay among the general population of Pakistan. Vaccines. 2021;9(7):720. doi: 10.3390/VACCINES9070720/S1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Motta M. Can a COVID-19 vaccine live up to Americans’ expectations? A conjoint analysis of how vaccine characteristics influence vaccination intentions. Soc Sci Med. 2021;272 doi: 10.1016/J.SOCSCIMED.2020.113642. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Kerekes S., Ji M., Shih S.-F., Chang H.-Y., Harapan H., Rajamoorthy Y., et al. Differential effect of vaccine effectiveness and safety on COVID-19 vaccine acceptance across socioeconomic groups in an international sample. Vaccines. 2021;9(9) doi: 10.3390/vaccines9091010. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.MacNeil J.R., Su J.R., Broder K.R., Guh A.Y., Gargano J.W., Wallace M., et al. Updated recommendations from the Advisory Committee on Immunization Practices for use of the Janssen (Johnson & Johnson) COVID-19 vaccine after reports of thrombosis with thrombocytopenia syndrome among vaccine recipients - United States, April 2021. MMWR Morb Mortal Wkly Rep. 2021;70(17):651–656. doi: 10.15585/mmwr.mm7017e4. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.FDA. FDA and CDC lift recommended pause on Johnson & Johnson (Janssen) COVID-19 vaccine use following thorough safety review | FDA; 2021. Retrieved December 16, 2021, from https://www.fda.gov/news-events/press-announcements/fda-and-cdc-lift-recommended-pause-johnson-johnson-janssen-covid-19-vaccine-use-following-thorough.
- 7.Zhang F., Shih S.-F., Harapan H., Rajamoorthy Y., Chang H.-Y., Singh A., et al. Changes in COVID-19 risk perceptions: methods of an internet survey conducted in six countries. BMC Res Notes. 2021;14(1) doi: 10.1186/s13104-021-05846-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Wagner AL. COVID-19 vaccine hesitancy surveys. Inter-university Consortium for Political and Social Research. Retrieved August 31, 2021; 2021. doi: 10.3886/E130422.
- 9.Wagner AL. COVID-19 questionnaires. figshare; 2021. doi: 10.6084/m9.figshare.14792058.v3.
- 10.Akel K.B., Masters N.B., Shih S.-F., Lu Y., Wagner A.L. Modification of a vaccine hesitancy scale for use in adult vaccinations in the United States and China. Hum Vaccin Immunother. 2021;17(8):2639–2646. doi: 10.1080/21645515.2021.1884476. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Mahase E. Covid-19: US suspends Johnson and Johnson vaccine rollout over blood clots. BMJ. 2021;373 doi: 10.1136/BMJ.N970. [DOI] [PubMed] [Google Scholar]
- 12.Merkley E., Loewen P.J. The correlates and dynamics of COVID-19 vaccine-specific hesitancy. Vaccine. 2022;40(13):2020–2027. doi: 10.1016/j.vaccine.2022.02.033. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Fielding J., Sullivan S.G., Beard F., Macartney K., Williams J., Dawson A., et al. Constructing an ethical framework for priority allocation of pandemic vaccines. Vaccine. 2021;39(5):797–804. doi: 10.1016/j.vaccine.2020.12.053. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.Mouter N., de Ruijter A., Ardine de Wit G., Lambooij M.S., van Wijhe M., van Exel J., et al. “Please, you go first!” preferences for a COVID-19 vaccine among adults in the Netherlands. Soc Sci Med. 2022;292 doi: 10.1016/J.SOCSCIMED.2021.114626. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15.Wagner A.L., Sheinfeld Gorin S., Boulton M.L., Glover B.A., Morenoff J.D. Effect of vaccine effectiveness and safety on COVID-19 vaccine acceptance in Detroit, Michigan, July 2020. Hum Vaccin Immunother. 2021;17(9):2940–2945. doi: 10.1080/21645515.2021.1917233. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Leask J., Chapman S., Hawe P., Burgess M. What maintains parental support for vaccination when challenged by anti-vaccination messages? A qualitative study. Vaccine. 2006;24(49–50):7238–7245. doi: 10.1016/J.VACCINE.2006.05.010. [DOI] [PubMed] [Google Scholar]
- 17.Thomson A., Robinson K., Vallée-Tourangeau G. The 5As: a practical taxonomy for the determinants of vaccine uptake. Vaccine. 2016;34(8):1018–1024. doi: 10.1016/j.vaccine.2015.11.065. [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
Data are available at: https://doi.org/10.3886/E130422.