Flu season is still raging in the United States, yet already it ranks among the most difficult in recent years. One reason: This year's vaccine has been just 36% effective against both A and B virus strains, the US Centers for Disease Control and Prevention estimated in Thursday's Morbidity and Mortality Weekly Report.


원문출처 : https://www.cnn.com/2018/02/15/health/flu-vaccine-effectiveness-cdc-feb-15/index.html