COVID protections wiped out a strain of flu.

For the first time, an influenza virus has been eliminated from the human population through non-pharmaceutical interventions. The public-health protections brought in during the COVID-19 pandemic — such as wearing a mask, social distancing and better ventilation — seem to have eliminated the influenza B/Yamagata lineage; no cases have been confirmed since March 2020. In September, the World Health Organization recommended that countries no longer include Yamagata-lineage antigens in flu vaccines, and US Food and Drug Administration advisors have now voted to remove it from flu jabs in the United States.

CNN | 5 min read

Reference: The Lancet Infectious Diseases editorial