Child COVID-19 vaccine uptake among participants of the 2015 Pelotas (Brazil) Birth Cohort Study

Objective: To analyze COVID-19 vaccine uptake in children and to investigate factors associated with two outcomes variables: (a) not even beginning; (b) not completing the COVID-19 vaccine series. Methods: We used data of children aged 6-7 years from the 2015 Pelotas c Birth Cohort Study. COVID-19 vaccination status was collected from immunization cards and National Immunization Program Information System. Adjusted analyses were performed using a hierarchical model to identify factors associated with the two study outcomes. Results: Among 3867 children, 20.7 % (95 % CI, 19.5 %-22.0 %) did not even begin the 2-dose primary COVID19 vaccine series, and 28.2 % (95 % CI, 26.6 %-29.8 %) did not complete the series with the second dose. Children not even beginning the COVID-19 vaccine series were more likely to have a White mother, not to have obesity, to have a history of COVID-19 infection, to have received non-recommended drugs for COVID-19, to be afraid of needles, and to have an incomplete diphtheria-tetanus-pertussis (DTP) and poliovirus immunization schedule. Not completing the 2-dose series was associated with lower maternal age and education, mother's selfidentification as White or Brown, lower household income, lack of access to health services, not having completed the DTP and poliovirus immunization schedule and living with a person with a history of infection with COVID-19. Conclusion: The results highlight a vaccine-hesitant parents' group who chose not beginning the COVID-19 vaccine series of their children and, another group of parents who failure to complete the child's series due to difficulty accessing health services.