The flu vaccine has been more than 50% effective in preventing severe flu illness in children this season, says the US Centers for Disease Control and Prevention.
The vaccines are made each year to protect against three or four different kinds of flu virus. The ingredients are based on predictions of what strains will make people sick the following winter. It doesn’t always work out.
This flu season has featured two waves, each dominated by a different virus. Both of those flu bugs are considered dangerous to children, but tend not to be as dangerous to the elderly.
Health officials grew worried when it became clear that the vaccine didn’t match the Type B flu strain that ended up causing most early season illnesses. But the CDC estimates that the vaccine has been about 50% effective against that strain in children. And the vaccine has been about 55% effective among kids against the Type A strain that has caused a second wave of flu illnesses.