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.

Interim Estimates of 2021-22 Seasonal Influenza Vaccine Effectiveness - United States, February 2022.

In the United States, annual vaccination against seasonal influenza is recommended for all persons aged ≥6 months except when contraindicated (1). Currently available influenza vaccines are designed to protect against four influenza viruses: A(H1N1)pdm09 (the 2009 pandemic virus), A(H3N2), B/Victoria lineage, and B/Yamagata lineage. Most influenza viruses detected this season have been A(H3N2) (2). With the exception of the 2020-21 season, when data were insufficient to generate an estimate, CDC has estimated the effectiveness of seasonal influenza vaccine at preventing laboratory-confirmed, mild/moderate (outpatient) medically attended acute respiratory infection (ARI) each season since 2004-05. This interim report uses data from 3,636 children and adults with ARI enrolled in the U.S. Influenza Vaccine Effectiveness Network during October 4, 2021-February 12, 2022. Overall, vaccine effectiveness (VE) against medically attended outpatient ARI associated with influenza A(H3N2) virus was 16% (95% CI = -16% to 39%), which is considered not statistically significant. This analysis indicates that influenza vaccination did not reduce the risk for outpatient medically attended illness with influenza A(H3N2) viruses that predominated so far this season. Enrollment was insufficient to generate reliable VE estimates by age group or by type of influenza vaccine product (1). CDC recommends influenza antiviral medications as an adjunct to vaccination; the potential public health benefit of antiviral medications is magnified in the context of reduced influenza VE. CDC routinely recommends that health care providers continue to administer influenza vaccine to persons aged ≥6 months as long as influenza viruses are circulating, even when VE against one virus is reduced, because vaccine can prevent serious outcomes (e.g., hospitalization, intensive care unit (ICU) admission, or death) that are associated with influenza A(H3N2) virus infection and might protect against other influenza viruses that could circulate later in the season.

Prevalence and Characteristics of Providers' Care Coordination Communication With Schools.

OBJECTIVES: Care coordination between schools and medical providers promotes child health, particularly for children with physical, emotional, and behavioral challenges. The purpose of this study was to assess caregivers' reports of provider-school communication for their children. Further, the study assessed if communication rates varied by child demographic or health conditions. METHODS: This study was a cross-sectional analysis of the 2016-2017 National Survey of Children's Health focused on school-aged children (age 6-17 years; n = 18,160). Weighted frequencies overall and stratified by provider-school communication status are reported. Multivariable logistic regression examined associations of provider-school communication. RESULTS: Only 23.5% of the total sample reported provider-school communication. The highest caregiver-reported communication prevalence was for children with diabetes (68.0%). Behavioral/mental health conditions, chronic physical health conditions or having increased medical complexity and needs were significantly associated with increased communication compared to those without these conditions. Odds Ratio (OR) and 95% Confidence Intervals (CI) for children with a behavioral/mental health condition were OR: 1.28; CI: 1.02 to 1.61, for children with a chronic physical health condition were OR: 1.37; CI: 1.15 to 1.63 and for children with special health care needs or with medical complexity were OR: 2.15; CI: 1.75 to 2.64 and OR: 1.77; CI: 1.09 to 2.87, respectively. Significant communication differences existed for every health condition (P < 0.05) except for children who had a blood disorder (P = 0.365). CONCLUSIONS: Caregiver perception of provider-school communication is low and differences in reported rates existed between health conditions and complexity status. Further work is needed to support provider-school-family communication for children with physical, mental, behavioral, and complex health conditions.