The two messenger-RNA vaccines for COVID-19 are highly effective. At least early on.
But owing to the spread of new and more virulent variants of the SARS-CoV-2 pathogen, the natural tendency of some vaccinations to wane over time and the rushed way countries have administered vaccine doses, the mRNA jabs from Pfizer and Moderna have been getting noticeably less effective lately.
Now there’s a consensus forming among experts that the initial two doses of mRNA aren’t enough on their own. A booster shot isn’t just a good idea for a select few with weak immune systems or jobs that expose them to unvaccinated people. Boosters should be standard for everyone.