INTRODUCTION
The coronavirus disease 2019 (COVID-19) pandemic substantially disrupted well-child visits and vaccinations in the United States.1,2 Parent hesitancy for pediatric COVID-19 vaccines3 and widespread vaccine misinformation during the pandemic may have affected parent confidence in routine childhood vaccines. Little is known beyond two studies: one involved a convenience sample from a single medical center;4 the other evaluated adolescent vaccines only.5 Using longitudinal data from a nationally representative sample, we assessed how parents’ confidence in childhood vaccines changed during the pandemic.
METHODS
We analyzed data from the Understanding America Study (UAS), a probability-based internet panel of approximately 9,500 US adults.6 Panel members were recruited using address-based sampling and provided with internet-enabled tablets if needed.
Understanding Coronavirus in America surveys were administered to the UAS panel (in English and Spanish) biweekly from April 1, 2020 – February 16, 2021, then monthly through July 20, 2021, with two additional surveys from September 23 – October 1, 2021 and February 1 – March 30, 2022 (Appendix). In every wave except for two, respondents were asked whether they agreed with four statements (presented in random order) about childhood vaccines: “Childhood vaccines, such as those for measles or chicken pox: 1) provide important benefits to society; 2) may lead to illness or death; 3) have many known harmful side effects; 4) are useful and effective” (Response options: Strongly Agree/Agree/Disagree/Strongly Disagree). These questions were omitted in the June 10 – July 8, 2020 and July 8 – August 5, 2020 surveys due to cost constraints.
We identified parents of children aged 0 – 17 years among UAS panel members based on responses to My Household surveys, administered quarterly to all panel members to assess household characteristics (Appendix). We examined trends in the percentage of parents who strongly agreed or agreed with each statement. For the “illness or death” and “harmful side effects” statements, we used linear regression models with cluster robust standard errors at the respondent level to assess characteristics associated with change between the first (April 1 – 28, 2020) and most recent (Feb 1, 2022 – March 30, 2022) waves. Analyses used SAS 9.4 (Cary, NC), were adjusted using survey sampling weights, and utilized exempt data under the UAS Data Use Agreement.
RESULTS
Across all survey waves, the weighted sample size of parent respondents ranged from 1,412 to 1,987. Parent response rates ranged from 96.9% to 71.5% in the first and last survey waves, respectively, and were similar to those of the overall panel (97.1% and 75.8% for the first and last waves, respectively).
From April 2020 to March 2022, the percentage of parents who agreed with the “important benefits” and “useful and effective” statements remained stable and very high, ranging from 89.5% – 92.5% and from 89.3% – 93.2%, respectively (Figure). By contrast, the percentage of parents who agreed with the “illness or death” and “harmful side effects” statements increased significantly by 13.2% (95% confidence interval [CI]: 9.4%, 16.9%) and 6.1% (95% CI: 2.2%, 9.9%), respectively (Table). Statistically significant increases were observed for most parent subgroups (with overlapping CIs noted, suggesting no statistically significant differences between subgroups).
Figure. Percentage of parents who strongly agree or agree that childhood vaccines: provide important benefits to society; are useful and effective; may lead to illness or death; have many known harmful side effects; April 1, 2020 – March 30, 2022.
Error bars correspond to the 95% CI for each point estimate.
Table.
Percentage of Parents Who Stated in April 2020 and February 2022 That They Strongly Agree or Agree That Childhood Vaccines May Lead to Illness or Death and Have Many Known Harmful Side Effects, Including Change Over Time.
| Childhood vaccines may lead to illness or death | ||||||
|---|---|---|---|---|---|---|
| April 1 – 28, 2020 | Feb 1 – Mar 30, 2022 | |||||
| Weighted sample size | Strongly agree or agree, % (95% CIa) | Weighted sample size | Strongly agree or agree, % (95% CIa) | Change over time: April 2020 survey to February 2022 survey, % (95% CIa)b | ||
| Overall | 1412 | 18.3% (15.4%, 21.3%) | 1488 | 31.5% (28.1%, 34.8%) | 13.2% (9.4%, 16.9%) | |
| Age (years) | ||||||
| 18–39 | 867 | 19.3% (15.3%, 23.3%) | 802 | 34.8% (29.8%, 39.8%) | 15.5% (10.2%, 20.9%) | |
| 40–49 | 360 | 15.2% (10.1%, 20.3%) | 428 | 28.7% (23.4%, 34.1%) | 13.6% (6.6%, 20.5%) | |
| 50+ | 185 | 19.9% (12.7%, 27.1%) | 258 | 25.6% (18.7%, 32.5%) | 5.7% (−2.9%, 14.3%) | |
| Gender | ||||||
| Female | 798 | 21.1% (17.0%, 25.3%) | 831 | 36.8% (32.2%, 41.3%) | 15.6% (10.6%, 20.7%) | |
| Male | 614 | 14.7% (10.7%, 18.7%) | 657 | 24.8% (20.1%, 29.4%) | 10.1% (4.7%, 15.5%) | |
| Education | ||||||
| High School or Less | 477 | 23.2% (17.1%, 29.3%) | 502 | 35.1% (28.6%, 41.7%) | 12.0% (4.2%, 19.7%) | |
| Some College | 383 | 20.4% (15.0%, 25.9%) | 414 | 37.6% (31.5%, 43.7%) | 17.2% (9.9%, 24.4%) | |
| Bachelor’s or More | 552 | 12.6% (8.9%, 16.3%) | 572 | 23.8% (19.2%, 28.4%) | 11.2% (6.7%, 15.7%) | |
| Foreign born | ||||||
| Yes | 182 | 13.4% (5.2%, 21.5%) | 203 | 22.6% (14.1%, 31.2%) | 9.3% (−1.8%, 20.4%) | |
| No | 1230 | 19.0% (15.9%, 22.2%) | 1285 | 32.9% (29.3%, 36.4%) | 13.8% (9.9%, 17.8%) | |
| Race and ethnicityc | ||||||
| Asian | 61 | 2.6% (0.0%, 5.8%) | 62 | 16.0% (4.0%, 27.9%) | 13.4% (1.6%, 25.2%) | |
| Black | 187 | 25.4% (16.0%, 34.9%) | 204 | 41.2% (30.9%, 51.5%) | 15.8% (3.5%, 28.1%) | |
| Hispanic | 273 | 18.5% (10.2%, 26.8%) | 320 | 27.3% (19.1%, 35.6%) | 8.8% (−0.6%, 18.3%) | |
| White | 823 | 17.2% (13.8%, 20.6%) | 841 | 32.0% (28.0%, 36.0%) | 14.8% (10.4%, 19.2%) | |
| Political affiliation | ||||||
| Democrat | 460 | 12.0% (7.9%, 16.1%) | 502 | 22.6% (17.5%, 27.7%) | 10.6% (4.6%, 16.5%) | |
| Republican | 463 | 17.2% (12.2%, 22.1%) | 469 | 31.5% (25.8%, 37.3%) | 14.4% (8.3%, 20.5%) | |
| Other | 323 | 29.0% (21.7%, 36.4%) | 371 | 42.7% (35.5%, 49.9%) | 13.7% (5.5%, 21.9%) | |
| Received at least one dose or likely to receive COVID vaccine | ||||||
| Yes | 978 | 12.7% (9.7%, 15.8%) | 1053 | 24.0% (20.4%, 27.6%) | 11.3% (6.9%, 15.6%) | |
| No | 432 | 31.0% (24.6%, 37.4%) | 431 | 49.1% (42.4%, 55.8%) | 18.1% (9.8%, 26.3%) | |
| Age of child(ren) (years)d | ||||||
| 0 – 4 | 452 | 18.7% (13.3%, 24.1%) | 438 | 29.0% (22.9%, 35.1%) | 10.3% (3.4%, 17.2%) | |
| 5 – 11 | 702 | 19.0% (14.6%, 23.4%) | 713 | 31.6% (26.7%, 36.5%) | 12.6% (7.2%, 18.0%) | |
| 12 – 17 | 558 | 17.7% (13.5%, 22.0%) | 624 | 33.4% (28.3%, 38.4%) | 15.6% (9.9%, 21.4%) | |
| Childhood vaccines have many known harmful side effects | ||||||
| April 1 – 14, 2020 | Feb 1 – Mar 30, 2022 | |||||
| Weighted sample size | Strongly agree or agree, % (95% CIa) | Weighted sample size | Strongly agree or agree, % (95% CIa) | Change over time: April 2020 survey to February 2022 survey, % (95% CIa)b | ||
| Overall | 1412 | 26.7% (23.3%, 30.1%) | 1488 | 32.8% (29.4%, 36.1%) | 6.1% (2.2%, 9.9%) | |
| Age (years) | ||||||
| 18–39 | 867 | 28.3% (23.7%, 32.9%) | 802 | 38.1% (33.1%, 43.2%) | 9.8% (4.5%, 15.2%) | |
| 40–49 | 360 | 24.0% (18.0%, 30.0%) | 428 | 26.2% (21.1%, 31.4%) | 2.2% (−5.0%, 9.4%) | |
| 50+ | 185 | 24.4% (16.4%, 32.3%) | 258 | 26.8% (19.8%, 33.9%) | 2.5% (−6.4%, 11.4%) | |
| Gender | ||||||
| Female | 797 | 29.7% (25.1%, 34.3%) | 831 | 39.0% (34.4%, 43.6%) | 9.3% (4.3%, 14.4%) | |
| Male | 614 | 22.8% (17.9%, 27.7%) | 657 | 24.8% (20.1%, 29.6%) | 2.0% (−3.8%, 7.8%) | |
| Education | ||||||
| High School or Less | 476 | 37.5% (30.6%, 44.4%) | 502 | 37.5% (30.9%, 44.0%) | 0.0% (−7.7%, 7.6%) | |
| Some College | 383 | 26.3% (20.3%, 32.3%) | 414 | 38.1% (31.9%, 44.2%) | 11.8% (4.3%, 19.2%) | |
| Bachelor’s or More | 552 | 17.6% (13.2%, 22.1%) | 572 | 24.7% (19.9%, 29.6%) | 7.1% (2.5%, 11.7%) | |
| Foreign born | ||||||
| Yes | 182 | 17.8% (9.1%, 26.4%) | 203 | 28.0% (18.8%, 37.2%) | 10.2% (−1.4%, 21.8%) | |
| No | 1229 | 28.0% (24.4%, 31.7%) | 1285 | 33.5% (29.9%, 37.1%) | 5.5% (1.5%, 9.5%) | |
| Race and ethnicityc | ||||||
| Asian | 61 | 6.5% (1.5%, 11.6%) | 62 | 23.0% (9.4%, 36.6%) | 16.5% (2.7%, 30.2%) | |
| Black | 187 | 44.6% (33.6%, 55.7%) | 204 | 42.9% (32.5%, 53.2%) | −1.8% (−14.2%, 10.7%) | |
| Hispanic | 273 | 26.8% (17.7%, 35.9%) | 320 | 36.3% (27.3%, 45.2%) | 9.5% (−0.8%, 19.8%) | |
| White | 823 | 23.7% (19.8%, 27.7%) | 841 | 29.3% (25.3%, 33.2%) | 5.5% (1.1%, 9.9%) | |
| Political affiliation | ||||||
| Democrat | 460 | 22.1% (16.6%, 27.6%) | 502 | 24.4% (19.2%, 29.7%) | 2.3% (−3.9%, 8.6%) | |
| Republican | 463 | 27.6% (21.7%, 33.4%) | 469 | 33.3% (27.5%, 39.2%) | 5.8% (−0.9%, 12.4%) | |
| Other | 323 | 33.7% (26.2%, 41.3%) | 371 | 44.4% (37.1%, 51.7%) | 10.7% (3.1%, 18.2%) | |
| Received at least one dose or likely to receive COVID vaccine | ||||||
| Yes | 977 | 16.6% (13.3%, 20.0%) | 1053 | 25.6% (21.8%, 29.4%) | 9.0% (4.4%, 13.6%) | |
| No | 432 | 49.0% (42.0%, 56.0%) | 431 | 49.7% (43.0%, 56.4%) | 0.7% (−8.0%, 9.4%) | |
| Age of childd | ||||||
| 0 – 4 | 451 | 24.6% (18.7%, 30.4%) | 438 | 32.2% (25.8%, 38.6%) | 7.6% (1.1%, 14.2%) | |
| 5 – 11 | 702 | 25.4% (20.6%, 30.3%) | 713 | 32.8% (27.9%, 37.8%) | 7.4% (1.9%, 12.8%) | |
| 12 – 17 | 558 | 27.7% (22.4%, 32.9%) | 624 | 34.3% (29.2%, 39.4%) | 6.6% (0.5%, 12.8%) | |
CI: Confidence interval.
To assess change over time, linear regression with cluster-robust standard errors was used to account for correlation of repeated measures and survey sampling weights. Change was deemed to be statistically significant if the 95% CI did not include 0. For clarity, statistically significant findings have been presented in boldface.
Race and ethnicity information was self-reported by panel members. Due to small sample sizes, race and ethnicity information has not been presented for American Indian or Alaska Native, Native Hawaiian or other Pacific Islander, or non-Hispanic multiracial groups.
Information about children’s ages was derived from My Household surveys, which are administered quarterly to Understanding America Study panel members to assess household demographics and composition; children’s ages are based on parental report. Children’s age categories are not mutually exclusive, as parents with multiple children may be assigned to more than one category depending on the ages of their children.
DISCUSSION
In this national sample, the proportion of parents concerned about safety and side effects for routine childhood vaccines increased significantly between April 2020 and March 2022; this trend was also observed for most parent subgroups. However, parent confidence in the benefits and effectiveness of childhood vaccines remained high. Our findings underscore the important role of pediatricians in addressing parents’ concerns about childhood vaccines, as they are highly trusted by parents about vaccinations7,8 and can address vaccine hesitancy.9,10 Pediatricians should therefore ask hesitant parents about their particular concerns and be prepared to address safety concerns.
Study strengths included use of a nationally representative sample and the ability to analyze trends using data frequently collected since the beginning of the pandemic. Limitations included: generalizability of online panel data (though UAS recruitment methods and use of survey weights in analyses should mitigate this bias); insufficient sample sizes for certain racial and ethnic groups; and inability to determine whether concern was higher or lower for specific childhood vaccines or the exact factors causing the observed rise in concern.
We conclude that parent concern about the safety of routine childhood vaccines has increased nationally since the start of the pandemic.
Supplementary Material
Funding/Support:
This work was supported by the University of Southern California and by Federal funds from the National Center for Advancing Translational Sciences (NCATS), National Institutes of Health, through the Clinical and Translational Science Awards (CTSA) Program (grant number UL1TR001881), the National Institute on Aging (grant number 5U01AG054580-03), and the National Science Foundation (grant number 2028683).
Role of Funder/Sponsor:
The sponsors had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
Abbreviations:
- COVID-19
Coronavirus disease 2019
- UAS
Understanding America Study
- CI
confidence interval
Footnotes
Conflict of Interest Disclosures: The authors have no conflicts of interest to report.
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