Influenza Cases Continue to Rise Early in the Year

The latest in influenza activity from the Centers for Disease Control and Prevention (CDC) showed an increase in cases, with the eastern and central regions of the US seeing the majority of reported cases.

Recent data from nationwide clinical laboratory testing recorded 4414 positive flue cases (3.8%), with a cumulative total of 26,946 cases since October 3, 2021.

During week 52, 4.8% of patient visits reported through ILINet nationwide were due to respiratory illness that included fever plus a cough or sore throat, which was above the national baseline. A total of 2615 patients with laboratory-confirmed influenza were admitted to the hospital.

Cases of influenza A (H3N2) were cited as being the most prevalent in the US during the early weeks of the 2021-2022 flu season. A majority of cases detected during the beginning of the 2021-2022 flu season were reported as being H3N2 cases.

Additionally, most H3N2 infections that occurred earlier in the season were among children and young adults ages 5-24 years, though in recent weeks the proportion of infection occurring among other age groups has been increasing, especially in adults aged 25 years and older.

Data from the National Center for Health Statistics (NCHS) mortality surveillance indicated that 19.9% of the deaths that occurred during the week ending January 1, 2022 were due to pneumonia, influenza, and COVID-19. The percentage was above the epidemic threshold of 6.9% for the week.

This dramatic increase was partly attributed to the rise in COVID-19 cases. Among the 3452 deaths reported for this week, 2519 had COVID-19 as an underlying or contributing cause of death, with 31 attributable to influenza.

This indicated that the current pneumonia and influenza-related mortality rates were primarily caused by COVID-19 rather than influenza.

The report observed early signs of flu vaccination uptake being down this season compared to the 2020-2021 flu season. The report noted that the current flu season was in a nascent state, and encouraged vaccinations and other flu prevention methods.