ABSTRACT
Background. Families with children may be at higher risk for influenza infection. Community transmission can suffer from underreporting as testing is often not performed. We studied the epidemiology of influenza in households with school-aged children using home-based sample collection. Methods. We conducted a remote household study surveilling respiratory viruses from November 2019-June 2021, in King County, Washington (WA), USA. Households with school-aged children were enrolled, mailed home specimen collection kits, and asked to self-assess for weekly acute respiratory illness (ARI) using remote survey platforms. Participants with ARI symptoms were prompted to complete serial illness surveys and self-collect/parent collect mid-turbinate nasal swabs. Samples were sent to a University of Washington study laboratory for RT-PCR influenza testing. Influenza rates were compared to WA Department of Health (DOH) reporting. Results. A total of 1861 ARI events were reported among 992 adults and 869 children in 470 households;75 influenza cases were detected (36 influenza A and 39 influenza B). The study participant median age was 32 years (0-84), 10 years (1-49) for influenza A, and 11 years (3-49) for influenza B cases. Overall 13% of households had an influenza case, of which 13 (22%) reported >1 case. A total of 81% of participants reported receipt of one dose of the 2019-2020 influenza vaccine, including 91% of influenza A and 90% of influenza B cases, and 84% received the 2020-2021 influenza vaccine. Like WA DOH, we observed a wave of influenza B cases followed by influenza A in 2019-2020. During influenza season 2020-2021, WA DOH reported 9 positive influenza tests and none observed in our study. Commonly, influenza case-patients reported were fever, cough, rhinorrhea, and fatigue. GI symptoms were more common in children than adults. Of the cases, 92% of influenza A and 78% of influenza B occurred in children. Conclusion. Influenza illness in 2019-2020 was initially influenza B, and subsequently replaced by influenza A. Most cases were in children and adolescents, despite at least one dose of influenza vaccine. Symptoms were widely distributed and similar between influenza A and B. Influenza incidence in our cohort declined to zero with the rise of SARS-CoV-2 cases and widespread mitigation efforts. (Figure Presented).
ABSTRACT
Background. In the United States, booster vaccines for persons 18 years and older were approved under Emergency Use Authorization (EUA) in September 2021. Waning immunity following SARS-CoV-2 primary vaccination series led to recommendations for booster vaccination. Emerging data suggest that providing boosters different from the primary series (heterologous vaccination) may provide a broader immune response than boosting with the same vaccine (homologous vaccination). CDC recommended the Pfizer-BioNTech BNT162b2 30-mug mRNA booster vaccine to clinical trial participants >6 months post study vaccines if not planned for boosting within the study. Methods. We conducted an observational study of persons who received 2 doses of Novavax protein-based NVX-CoV2373 vaccine 21 days apart, in a Phase 3 clinical trial, and subsequently received a Pfizer BNT162b2 booster vaccine under EUA. Serologic assays, including the Roche anti-nucleocapsid (N) IgG and anti-Spike (S) IgG, were performed on blood collected pre-booster (D0) and on days 18 (D18) and 34 (D34) post-booster vaccine. The anti-S IgG geometric means (GMTs) were calculated over study time points. Wilcoxon signed rank test was performed to compare anti-S IgG response between D0 and D18 and D0 and D34. Results. Of 26 participants enrolled, 16 (57%) were women;the median age was 47 years (range 29-67). Roche anti-N antibodies were negative at all visits. Time from second NVX-CoV2373 vaccine to Pfizer BNT162b2 booster was a median of 10.4 months in 54% of participants and 7 months in 46% of participants. Anti-S IgG GMTs were 222 BAU/ml D0, 24,723 BAU/ml D18, and 24,584 BAU/ml D34 (p< 0.0001 for comparisons of D0 with D18 & D34). Overall, participants tolerated the booster vaccine without significant adverse events. Cell mediated immunity and D614G pseudovirus neutralizing antibody assays are in progress. Figure 1. Anti-S IgG titers pre and post-booster vaccine 16 participants included with all 3-time study time points for comparison. Conclusion. Two doses of NVX-CoV2373 vaccine followed by the Pfizer BNT162b2 booster vaccine resulted in ~100-fold increase in anti-S IgG against SARS-CoV-2. No participant had evidence of prior SARS-CoV-2 infection by anti-N IgG. Two doses of NVX-CoV2373 vaccine followed by one dose of Pfizer BNT162b2 vaccine is an effective and well-tolerated regimen for boosting anti-S IgG against SARS-CoV-2.