'Forever boosting': Why some scientists oppose repeated Covid-19 shots

Everyone should get a booster shot. In the long run, though, doses every few months aren't a viable public health strategy, scientists say

A year ago, just two doses of a Covid-19 vaccine — or even one, in the case of Johnson & Johnson’s formulation — were thought to offer sufficient protection against the coronavirus.

Now, faced with the extraordinarily contagious Omicron variant, Israel has begun offering fourth doses to some high-risk groups. On Wednesday, the Centers for Disease Control and Prevention expanded eligibility for boosters to adolescents and backed away from describing anyone as “fully vaccinated” because two shots no longer seem adequate.

Instead, one’s vaccination status will now be “up to date” — or not. It’s no surprise that many Americans are wondering: