ABSTRACT
Background. Longitudinal serological surveillance is critical to understand dynamics of SARS-CoV-2 infections in children, a substantial portion of whom are asymptomatic. We describe trends in seroprevalence using at-home testing and evaluate demographic and clinical characteristics associated with seroconversion. Methods. Children 2-17 years old enrolled at 3 North Carolina sites (Figure 1) were followed April 2- December 31, 2021. Daily electronic surveys solicited symptoms and vaccination status. Four fingerprick lateral flow immunoassay tests were shipped to participants to be completed monthly;sensitivity and specificity were 84.5% and 99.0%, respectively. We defined an infection window as 30 days before a positive antibody test (IgG), excluding results after any vaccine. Asymptomatic was defined as absence of "new" symptoms in the window;"new" was defined as not occurring the 14 days preceding the first observation of the symptom in the window. Univariate logistic regression was used to compare participants with and without infection-induced antibodies. For estimated seroprevalence, we used Bayesian inference accounting for sensitivity and specificity, modeling IgG positives from a binomial distribution. Results. Of 1,501 participants, 9.1% developed infection-induced antibody (Table 1). Blacks were more likely to seroconvert (OR 1.95 [95% CI 1.05-3.45]) as were those in a 5-or-more person household (OR 4.25 [CI 1.47-12.1]). Cumulative seroprevalence of SARS-CoV-2 increased from 12.7% in May to 32.4% in October (Figure 2);61% of those seropositive were asymptomatic (Table 2). Adolescents had the highest seroconversion rates and were significantly more likely than 2-4-year olds to be asymptomatic. Conclusion. Prior SARS-CoV-2 seroprevalence data in children are limited by cross sectional design and use of convenience samples. With serial testing, we demonstrate rising SARS-CoV-2 seroprevalence, with highest rates of seroconversion in adolescents. Although prior findings suggest that asymptomatic infections occur most frequently in young children, we found a high proportion among adolescents. Our findings underscore the importance of serosurveillance to optimize public health efforts aimed at children and adolescents. (Table Presented).
ABSTRACT
Background. The COVID-19 Community Research Partnership (CCRP) is a large multicenter healthcare system-based study of the COVID-19 pandemic, including factors impacting risk of infection and hospitalization. The CCRP includes a subset of immunocompromised (IC) participants with varying vaccination status over time. Methods. We conducted an observational cohort study of 2,515 IC and 41,941 non-IC CCRP participants who contributed electronic health record data and daily electronic surveys to self-report COVID-19 symptoms, test results, and vaccinations from April 2020 to March 2022. The IC population included those with stem cell transplant, HIV, cancer, autoimmune disease, or solid organ transplant. The latter 3 must have also had an active systemic therapy to meet the IC condition (e.g. chemotherapy, immune modulator, steroid). Logistic regression was used to investigate risk of COVID-19 and hospitalization among IC participants and according to vaccine status within viral variant time periods (pre-delta, delta, omicron). Results. IC conditions included cancer (51%), autoimmune (41%), solid organ/ stem cell transplant (9%), and HIV (7%). The IC group was older and had more comorbidities. 95% of vaccine recipients received an mRNA vaccine. More vaccine breakthrough infections occurred in the IC group than non-IC group (36.1% vs 29.5%, p< 0.001). IC participants were less likely to remain COVID-19 free over time if vaccinated but not boosted (Fig 1A). However, after receiving a booster there was no difference in COVID-19 cases between the groups (Fig 1B). IC participants were more likely to be hospitalized with COVID-19 (OR 2.85;95% CI 1.69-4.76), but vaccination reduced risk for hospitalization (OR 0.26;95% CI 0.08-0.8). Receipt of a booster dose reduced risk of COVID-19 among IC participants during the delta wave (IRR 0.52;95% CI 0.28-0.94) but not during omicron. However, during omicron risk of hospitalization in the IC group was reduced by a booster dose (OR 0.13;95% CI 0.02-0.72). Conclusion. IC individuals were at increased risk for COVID-19 hospitalizations and breakthrough infections. After receiving a booster, IC participants were conferred the same level of protection from infection as their non-IC counterparts, highlighting the importance of boosters for these individuals. (Figure Presented).