key: cord-1045696-4kr1m6ax
authors: Czeisler, M. E.; Rajaratnam, S. M. W.; Howard, M. E.; Czeisler, C. A.
title: COVID-19 Vaccine Intentions in the United States, December 2020 to March 2021
date: 2021-05-17
journal: nan
DOI: 10.1101/2021.05.16.21257290
sha: a8cd0be4e877c7274882ba6a7b7f2d7e6ac4c019
doc_id: 1045696
cord_uid: 4kr1m6ax

Importance SARS-CoV-2 containment is estimated to require attainment of high (>80%) post-infection and post-vaccination population immunity. Objective To assess COVID-19 vaccine intentions among US adults and their children, and reasons for vaccine hesitancy among potential refusers. Design Internet-based surveys were administered cross-sectionally to US adults during December 2020 and February to March 2021 (March-2021). Setting Surveys were administered through Qualtrics using demographic quota sampling. Participants A large, demographically diverse sample of 10,444 US adults (response rate, 63.9%). Main Outcomes and Measures COVID-19 vaccine uptake, intentions, and reasons for potential refusal. Adults living with or caring for children aged 2 to 18 years were asked about their intent to have their children vaccinated. Multivariable weighted logistic regression models were used to estimate adjusted odds ratios for vaccine refusal. Results Of 5256 March-2021 respondents, 3467 (66.0%) reported they would definitely or most likely obtain a COVID-19 vaccine as soon as possible (ASAP Obtainers), and an additional 478 (9.1%) reported they were waiting for more safety and efficacy data before obtaining the vaccine. Intentions for children and willingness to receive a booster shot largely matched personal COVID-19 vaccination intentions. Vaccine refusal (ie, neither ASAP Obtainers nor waiting for more safety and efficacy data) was most strongly associated with not having obtained an influenza vaccine in 2020 (adjusted odds ratio, 4.11 [95% CI, 3.05-5.54]), less frequent mask usage (eg, rarely or never versus always or often, 3.92 [2.52-6.10]) or social gathering avoidance (eg, rarely or never versus always or often, 2.65 [1.95-3.60]), younger age (eg, aged 18-24 versus over 65 years, 3.88 [2.02-7.46]), and more conservative political ideology (eg, very conservative versus very liberal, 3.58 [2.16-5.94]); all P<.001. Conclusions and Relevance Three-quarters of March-2021 respondents in our large, demographically diverse sample of US adults reported they would likely obtain a COVID-19 vaccine, and 60% of adults living with or caring for children plan to have them vaccinated as soon as possible. With an estimated 27% of the US population having been infected with SARS-CoV-2, once vaccines are available to children and they have been vaccinated, combined post-infection and post-vaccination immunity will approach 80% of the US population in 2021, even without further infections.

Of 5256 March-2021 respondents, 3467 (66.0%) reported they would definitely or most likely obtain a COVID-19 vaccine as soon as possible (ASAP Obtainers), and an additional 478 (9.1%) reported they were waiting for more safety and efficacy data before obtaining the vaccine. Intentions for children and willingness to receive a booster shot largely matched personal COVID-19 vaccination intentions. Vaccine refusal (ie, neither ASAP Obtainers nor waiting for more safety and efficacy data) was most strongly associated with not having obtained an influenza vaccine in 2020 (adjusted odds ratio, 4 

Three-quarters of March-2021 respondents in our large, demographically diverse sample of US adults reported they would likely obtain a COVID-19 vaccine, and 60% of adults living with or caring for children plan to have them vaccinated as soon as possible. With an estimated 27% of the US population having been infected with SARS-CoV-2, once vaccines are available to children and they have been vaccinated, combined post-infection and post-vaccination immunity will approach 80% of the US population in 2021, even without further infections.

As of mid-May 2021, the US Food & Drug Administration (FDA) has granted Emergency Use Authorization for 3 coronavirus disease 2019 (COVID-19) vaccines (Pfizer-BioNTech, Moderna, and Janssen), 1 and nearly 60% of US adults have been fully (120 million) or partially (35 million) vaccinated. 2 Consistent with vaccine prioritization, 3 ~85% of adults aged 65-plus years have received vaccines. 2 Early indicators demonstrate high efficacy of these vaccines in reducing severe acute respiratory coronavirus syndrome 2 (SARS-CoV-2) transmission and severe COVID-19

outcomes. [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] These represent remarkable public health and scientific achievements.

Yet, several obstacles remain to containing COVID-19 in the US and globally.

First, until recently, the rate-limiting steps in the US have been vaccine supplies and delivery capacity. Only now that supply is plentiful has vaccine hesitancy started to present as a barrier to vaccination en masse. Prior studies provided information for tailored educational programs to enhance informed COVID-19 vaccine decisionmaking. [15] [16] [17] [18] [19] [20] [21] [22] [23] Understanding groups that remain disproportionately vaccine hesitant, and common reasons for hesitancy, are critical to promote vaccination. CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted May 17, 2021. ;  https://doi.org/10.1101/2021.05. 16 .21257290 doi: medRxiv preprint neonates, 28 which is particularly important given substantially elevated risk of adverse maternal and neonatal health outcomes from SARS-CoV-2 infection. [29] [30] [31] [32] [33] Third, vaccine-evasive coronavirus variants could threaten post-vaccination immunity. Fortunately, the developed vaccines are effective against most common variants, 10,34 though more evasive variants have started to appear, 35 some of which may require modified COVID-19 vaccine boosters. 36, 37 Understanding COVID-19 booster vaccine intentions is therefore important.

We therefore assessed COVID-19 vaccine uptake, intentions, and reasons for hesitancy in a large, diverse sample of US adults, including pregnant people. We examined child vaccine intentions among parents and caregivers, and willingness to receive variant-protective COVID-19 booster vaccines.

From December 6-27, 2020 (December-2020) and February 16 

The December-2020 and March-2021 survey instruments comprised 136 and 160 items, respectively, and included questions about demographics, pandemic-related attitudes and behaviors, and mental health. Respondents were not informed of survey topics prior to commencement.

COVID-19 vaccination intentions were assessed using the question, "If an FDAapproved vaccine to protect against COVID-19 were widely accessible, would you get one as soon as possible?" Respondents answered using a five-item Likert scale: "No, definitely not," "Unlikely," "Maybe/Not sure," "Most likely," or "Yes, definitely". March-2021 respondents could also answer that they had been vaccinated against COVID-19.

Respondents who selected "No, definitely not," "Unlikely," or "Maybe/Not sure" selected among 8 reasons for not obtaining a vaccine as soon as possible (ASAP), with multiple selections allowed: waiting for more safety and efficacy data, low COVID-19 risk perception, beliefs the vaccine would not protect against COVID-19, the approval process was rushed, or that all vaccines are dangerous, concern of a hidden purpose, religious refusal, and other. March-2021 respondents who reported living with or caring for persons aged 2 to 18 years were asked about COVID-19 vaccination intentions for their children. All March-2021 respondents were asked about potential COVID-19 booster intentions.

. CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) 

Demographic characteristics assessed included sex, age, race/ethnicity, education attainment, pregnancy, parental or unpaid caregiver roles, and political ideology.

Medical mistrust was assessed using the Medical Mistrust Index (MMI), 38 with responses categorized into 4 levels (0-6, 7-13, 14-17, and 18-21). Higher scores reflect more mistrust. Respondents reported whether they had received an influenza vaccine last year or ever tested SARS-CoV-2-positive, and past-week frequency of mask usage in public and avoidance of 10-plus-person gatherings using 5-item Likert scales: never, rarely, sometimes, often, and always. 39

Intentions to receive COVID-19 vaccines in December-2020 and March-2021 were grouped as Decliners ("No, definitely not" or "Unlikely"), Undecideds ("Maybe/Not sure"), or ASAP Obtainers ("Most likely" or "Yes, definitely," plus March-2021 respondents who had already been vaccinated). A category of Overall Obtainers was created as ASAP Obtainers, plus respondents waiting for more safety and efficacy data (a subset of Decliners and Undecideds). Chi-square tests with design effect correction factors were used to test for differences between March-2021 subgroups (eg, male versus female respondents), and between the December-2020 and March-2021 samples within subgroups (eg, non-overlapping female respondents over time). Bonferroni adjustments of 9 and 33, respectively, were applied to account for multiple comparisons.

Weighted logistic regression models were used to estimate unadjusted and adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for vaccine Refusal (ie, Decliners, minus those waiting for safety and efficacy data) among March-2021 . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) Table 1 , the prevalence of Overall Obtainers differed significantly. In general, the prevalence was higher among respondents who were male versus female, older versus younger, Asian or Hispanic compared with Black, liberal versus conservative, and, among female respondents of childbearing age, those who were pregnant versus those who were not. The prevalence of Overall Obtainers was also higher among respondents who wore masks in public or avoided social gatherings more frequently, had received or planned to receive the influenza vaccine, and had lower levels of medical mistrust.

Refusal were highest among adults who had not received an influenza vaccine (aOR, 4.11 [95% CI, 3.05-5.54], P<.001) (Figure 1 , eTable 1). Refusal was also positively associated with less frequent mask usage (eg, rarely or never versus always or often, Among 1789 March-2021 Undecideds or Decliners, common reasons for potentially not being ASAP Obtainers were concern that the vaccine may be risky due to rushed approval (41.8%), plans to wait 6-12 months for safety and efficacy data (26.7%), concern of a hidden purpose (25.0%), and belief that the vaccine would not offer protection from COVID-19 (24.3%) or low COVID-19 risk perception (18.0%) ( . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) (1.6%) of these ASAP booster Obtainers ( Figure 3B ).

Nearly two-thirds of 5256 US adults surveyed during mid-February to early March 2021 reported they had obtained or would definitely or most likely obtain an FDAapproved COVID-19 vaccine as soon as possible, with up to three-quarters likely obtainers when including individuals waiting for more safety and efficacy data. Given that approximately 60% of the US adult population has received at least one dose of the COVID-19 vaccine as of May 15, 2021, 2 these data suggest that less than one-quarter of the remaining unvaccinated US adults planned to obtain vaccines ASAP, and less than one-half planned to ever be vaccinated against COVID-19. Vaccine Refusal was highest among adults who were younger, female, Black or other (versus White) race/ethnicity, very conservative politically, those with lower education attainment, more medical mistrust, lesser COVID-19 prevention behavior adherence, and those who had . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. To achieve high levels of immunity, engaging the Undecideds (15% of March-2021 respondents) will be critical. Young age, more centrist political ideology, and multigenerational caregiver status were associated with being Undecided, and may represent high-yield demographics to incentivize uptake. Interestingly, only one-quarter of young adult Undecideds indicated that they were waiting for more vaccine safety and efficacy data, suggesting that alternative incentives should be reviewed based on prior immunization programs 55-59 and investigated during the current rollout 60,61 (eg, monetary incentives, 62 vaccine mandates for return to campus, employer or workplace vaccination programs, or easing restrictions for vaccinated persons, such as those reported in recent CDC guidance 63 and the European Union's international travel ban for those fully vaccinated 64 ). Concurrently, ensuring equitable access to vaccines may reduce . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted May 17, 2021. ; https://doi.org/10.1101/2021.05.16.21257290 doi: medRxiv preprint disparities-particularly regarding internet connectivity and technology usability and literacy. 65 Monitoring and responding to SARS-CoV-2 variants will be essential. Development of vaccine boosters to combat vaccine-evasive variants is underway. Our results suggest that acceptance of COVID-19 vaccine boosters will largely reflect overall COVID-19 vaccination trends. To avoid further COVID-19 health disparities, improving vaccine uptake among groups with high levels of vaccine refusal will prove important.

Furthermore, the race against variants will occur globally. 66, 67 The US is among the high-income countries with abundant vaccine supply, while many low-and middleincome countries have struggled to initiate vaccination campaigns. 68, 69 Strengths of this study include assessment of COVID-19 vaccine and booster intentions in large, demographically diverse samples of US adults at multiple timepoints, and inclusion of diverse characteristics. Limitations include self-reported metrics that may not correlate with future behavior and Internet-based survey methods that may not fully represent the US population. However, our data for the prevalence of COVID-19 vaccine recipients as of mid-February to early March 2021 were consistent with nationwide surveillance data, 70 and 88.7% of respondents who had received 1 dose in a 2-dose regimen indicated that they planned to complete the series, consistent with CDC surveillance data (88.0%). 71

Projections of US population immunity are contingent on assumptions. 72, 73 First, post-vaccination population immunity requires efficacy against infection above 80%, 74 well below current estimates. 6 Second, evidence from other coronaviruses 75, 76 and preliminary reports of SARS-CoV-2 re-infection [77] [78] [79] or breakthrough infections among . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted May 17, 2021. ; https://doi.org/10.1101/2021.05.16.21257290 doi: medRxiv preprint fully vaccinated individuals [80] [81] [82] [83] suggest both vaccination-and infection-derived immunity may be transient, requiring re-vaccination. Third, current FDA-approved vaccines are not authorized for children aged under 12 years. Fourth, most current vaccines require multiple doses for maximal efficacy, presenting a barrier to distribution. 84 However, nearly 90% of people in 2-dose COVID-19 vaccine regiments received both doses, and more than 95% of completers did so within the recommended interval between the first and second doses. 71 Finally, considerable regional differences in vaccination rates will affect local transmission of the SARS-CoV-2 viral infections.

Our findings reveal that vaccine hesitancy is unlikely to prevent the US from achieving high levels of immunity against COVID-19 in 2021, and that intentions for vaccination of children and obtaining boosters largely match personal vaccine intentions. Vaccine education campaigns tailored for Undecideds, coupled with robust vaccine distribution programs, could enhance vaccine obtainment and assist in controlling the COVID-19 pandemic in the US.

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The copyright holder for this preprint this version posted May 17, 2021. ; https://doi.org/10.1101/2021.05.16.21257290 doi: medRxiv preprint Author Contributions: Mr Czeisler had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Czeisler, Czeisler.

Statistical analysis: Mr Czeisler. Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation or approval of the manuscript; and decision to submit the manuscript for publication.

. CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted May 17, 2021 . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted May 17, 2021 . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted May 17, 2021 . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)

The copyright holder for this preprint this version posted May 17, 2021. ; https://doi.org/10.1101/2021.05.16.21257290 doi: medRxiv preprint

. CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)

The copyright holder for this preprint this version posted May 17, 2021. ; https://doi.org/10.1101/2021.05.16.21257290 doi: medRxiv preprint

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Always or Often

) 154 (14.4) 259 (24.2) Black, non-Hispanic or Often 1174 (65.6) 367 (31.2)

Plan to wait 6