To understand the influence of a novel infectious disease epidemic on parent general attitudes about childhood vaccines.We conducted a natural experiment utilizing cross-sectional survey data from parents of infants in Washington and Colorado participating in a larger trial that began on September 27, 2019. At enrollment, parents completed the short version of the Parental Attitudes about Childhood Vaccines (PACV-SF), a validated survey scored from 0 to 4, with higher scores representing more negative attitudes. The exposure variable was onset of the SARS-CoV-2 pandemic in the United States, with the before-period defined as September 27, 2019 to February 28, 2020 and the after-period defined as April 1, 2020-December 10, 2020, with the after-period further separated into proximate (April 1, 2020-July 31, 2020) and distant periods (August 1, 2020-December 10, 2020). The outcome variable was parent negative attitudes about childhood vaccines, defined as a score of ≥2 on the PACV-SF. We estimated the probability of the outcome after (vs before) the exposure using log-binomial regression with generalized estimating equations adjusted for demographic confounding variables.Among 4562 parents, the risk of negative attitudes was lower immediately after (vs before) SARS-CoV-2 onset (adjusted risk ratio [aRR] = 0.58; 95% confidence interval [CI], 0.36, 0.94; P = .027), but by August-December 2020, the average rate of negative attitudes was 35% higher than during April-July 2020 (aRR: 1.35; 95% CI: 1.13, 1.61; P = .0009).A reduced risk of negative general vaccine attitudes observed immediately after SARS-CoV-2 onset was quickly attenuated.
