This Year's Flu Shot Only Worked a Third of the Time, CDC Says

Early estimates suggest the flu shot only worked about a third of the time this year.

Between Nov. 2 and Feb. 3, total vaccine effectiveness was estimated at 36%, according to a report released Thursday by the CDC. When broken down by strain, however, efficacy varied widely.

H3N2, the dominant strain circulating this flu season, is notoriously more virulent and less receptive to vaccination than other types of influenza.