Introduction: Observational studies of SARS-CoV-2 vaccine effectiveness depend on accurate ascertainment of vaccination receipt, date, and product type. Self-reported vaccine data may be more readily available to and less expensive for researchers than assessing medical records. Methods: We surveyed adult participants in the COVID-19 Community Research Partnership who had an authenticated Electronic Health Record (EHR) (N = 41,484) concerning receipt of SARS-CoV-2 vaccination using a daily survey beginning in December 2020 and a supplemental survey in September–October 2021. We compared self-reported information to that available in the EHR for the following data points: vaccine brand, date of first dose, and number of doses using rates of agreement and Bland–Altman plots for visual assessment. Self-reported data was available immediately following vaccination (in the daily survey) and at a delayed interval (in a secondary supplemental survey). Results: For the date of first vaccine dose, self-reported “immediate” recall was within ±7 days of the date reported in the “delayed” survey for 87.9% of participants. Among the 19.6% of participants with evidence of vaccination in their EHR, 95% self-reported vaccination in one of the two surveys. Self-reported dates were within ±7 days of documented EHR vaccination for 97.6% of the “immediate” surveys and 92.0% of the “delayed” surveys. Self-reported vaccine product details matched those in the EHR for over 98% of participants for both “immediate” and “delayed” surveys. Conclusions: Self-reported dates and product details for COVID-19 vaccination can be a good surrogate when medical records are unavailable in large observational studies. A secondary confirmation of dates for a subset of participants with EHR data will provide internal validity.

Coronavirus Disease-2019 (COVID-19) vaccine acceptance is variable. We surveyed participants in the COVID-19 Community Research Partnership from 17 December 2020 to 13 January 2021 to assess vaccine receptiveness. Vaccine uptake was then monitored until 15 May 2021; 20,232 participants responded to the receptiveness survey with vaccination status accessed in 18,874 participants via daily follow-up surveys (participants not completing daily surveys ≥30 days to 15 May 2021, were excluded). In the initial survey, 4802 (23.8%) were vaccine hesitant. Hesitancy was most apparent in women (Adjusted RR 0.93, p < 0.001), Black Americans (Adjusted RR 1.39, 1.41, 1.31 to non-Hispanic Whites, Other, and Hispanic or Latino, respectively p < 0.001), healthcare workers (Adjusted RR 0.93, p < 0.001), suburbanites (ref. Urban Adjusted RR 0.85, 0.90 to urban and rural dwellers, respectively, p < 0.01), and those previously diagnosed with COVID-19 (RR 1.20, p < 0.01). Those <50 years were also less accepting of vaccination. Subsequent vaccine uptake was 99% in non-hesitant participants. For those who were unsure, preferred not to answer, or answered “no”, vaccination rates were 80% (Adjusted RR 0.86, p < 0.0001), 78% (Adjusted RR 0.83, p < 0.0001), and 52.7% (Adjusted RR 0.65, p < 0.0001), respectively. These findings suggest that initial intent did not correlate with vaccine uptake in our cohort.

During the COVID-19 pandemic, longitudinal serological surveillance was critical to accurately assess the cumulative incidence of COVID-19 and monitor population-level immunity among children. We characterized the epidemiology of COVID-19 among North and South Carolina children using remote electronic symptom surveillance and serial at-home antibody testing in 2–17-year-old children from April to December 2021. We estimated accumulation of infection-induced antibodies, defined as seropositivity before vaccination. Reported novel symptoms were characterized for seropositive and seronegative participants. A total of 1058 children (median age 10 years (IQR 7–13)) participated in symptom surveillance. Estimated cumulative prevalence of infection-induced antibody increased from 0% (0–60%) to 85.7% (31.6–97%), 3.1% (0–9.0%) to 61.7% (46.1–72.7%) and 5.6% (0–15.6%) to 75% (59.9–84.4%), respectively, among those aged 2–4, 5–11 and 12–17 years. Determinants of seropositivity included Black race (OR 2.06 (1.19 to 3.47)) and having >5 household members (OR 3.05 (1.21 to 7.45)). Participants seroconverting reported mostly respiratory or systemic symptoms, but 52% (28/52) were asymptomatic. We demonstrate the role of at-home testing in trending SARS-CoV-2 seroprevalence in a community cohort of children. Such regional serological surveillance complements national data for a more complete assessment of SARS-CoV-2 burden and transmission. Future applications of the remote surveillance platform may be leveraged for characterizing the epidemiology of novel pathogens.