Influenza Vaccine Effectiveness Against Influenza A(H3N2)-Related Illness in the United States During the 2021-2022 Influenza Season.

BACKGROUND: In the United States, influenza activity during the 2021-2022 season was modest and sufficient enough to estimate influenza vaccine effectiveness (VE) for the first time since the beginning of the coronavirus disease 2019 pandemic. We estimated influenza VE against laboratory-confirmed outpatient acute illness caused by predominant A(H3N2) viruses. METHODS: Between October 2021 and April 2022, research staff across 7 sites enrolled patients aged ≥6 months seeking outpatient care for acute respiratory illness with cough. Using a test-negative design, we assessed VE against influenza A(H3N2). Due to strong correlation between influenza and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination, participants who tested positive for SARS-CoV-2 were excluded from VE estimations. Estimates were adjusted for site, age, month of illness, race/ethnicity, and general health status. RESULTS: Among 6260 participants, 468 (7%) tested positive for influenza only, including 440 (94%) for A(H3N2). All 206 sequenced A(H3N2) viruses were characterized as belonging to genetic group 3C.2a1b subclade 2a.2, which has antigenic differences from the 2021-2022 season A(H3N2) vaccine component that belongs to clade 3C.2a1b subclade 2a.1. After excluding 1948 SARS-CoV-2-positive patients, 4312 patients were included in analyses of influenza VE; 2463 (57%) were vaccinated against influenza. Effectiveness against A(H3N2) for all ages was 36% (95% confidence interval, 20%-49%) overall. CONCLUSIONS: Influenza vaccination in 2021-2022 provided protection against influenza A(H3N2)-related outpatient visits among young persons.

African National Public Health Institutes Responses to COVID-19: Innovations, Systems Changes, and Challenges.

National public health institutes (NPHIs)-science-based governmental agencies typically part of, or closely aligned with, ministries of health-have played a critical part in many countries' responses to the COVID-19 pandemic. Through listening sessions with NPHI leadership, we captured the experiences of NPHIs in Africa. Our research was further supplemented by a review of the literature. To address issues related to COVID-19, NPHIs in Africa developed a variety of innovative approaches, such as working with the private sector to procure and manage vital supplies and address key information needs. Creative uses of technology, including virtual training and messaging from drones, contributed to sharing information and battling misinformation. Positive impacts of the pandemic response include increased laboratory capacity in many countries, modernized surveillance systems, and strengthened public-private partnerships; much of this enhanced capacity is expected to persist beyond the pandemic. However, several challenges remain, including the lack of staff trained in areas like bioinformatics (essential for genomic analysis) and the need for sustained relationships and data sharing between NPHIs and agencies not traditionally considered public health (eg, those related to border crossings), as well as the impact of the pandemic on prevention and control of non-COVID-19 conditions-both infectious and noncommunicable. Participants in the listening sessions also highlighted concerns about inequities in access to, and quality of, the public health services and clinical care with resultant disproportionate impact of the pandemic on certain populations. COVID-19 responses and challenges highlight the need for continued investment to strengthen NPHIs and public health infrastructure to address longstanding deficiencies and ensure preparedness for the next public health crisis.