U.S. Flu Season Outlook
Early data indicates a potentially challenging influenza season for the United States this winter. Richard Webby, a flu researcher at St. Jude Children's Research Hospital, noted that signs suggest a significant season.
Global Indicators
Patterns in the southern hemisphere's winter flu activity often serve as a predictor for the northern hemisphere. The southern hemisphere experienced notable flu activity, which extended for a longer duration than typical. Subsequently, parts of the northern hemisphere, including the United Kingdom, have reported increased flu cases.
Dominant Strain and Vaccine Efficacy
The Centers for Disease Control and Prevention (CDC) flu tracker identifies H3N2 as the dominant flu virus strain in the northern hemisphere thus far. H3N2 viruses are generally associated with higher activity and a greater incidence of severe disease. The 2016-2017 flu season was last significantly dominated by H3N2.
A new variant of the H3N2 virus has recently emerged and become the prevalent strain in the U.S. Epidemiologist Caitlin Rivers from Johns Hopkins explained that this mutation may enable the virus to circumvent existing immunity from previous infections or vaccinations. Consequently, the current flu vaccine may not offer an optimal match against this new variant.
However, data from the U.K. suggest that vaccines provide protection against severe outcomes. U.K. data indicate vaccine effectiveness of approximately 70% to 75% against hospitalization in children and 30% to 40% against hospitalization in adults.
Recommendations and Concerns
Health officials advise individuals who have not yet received a flu shot to do so promptly. Immunity typically develops within two weeks of vaccination. Influenza is responsible for an estimated 12,000 to 52,000 deaths annually in the U.S.
Caitlin Rivers expressed concerns regarding potentially lower uptake of both influenza and COVID-19 vaccines this year.
A spokesperson for the Department of Health and Human Services (HHS) stated that it is currently "too early to know what viruses will spread this season, in what proportion, and how well the vaccine will work in the United States." The HHS statement concluded that the decision to vaccinate is personal, and individuals should consult their healthcare provider regarding vaccine risks and benefits.