John Moore, an immunologist and microbiologist at Weill Cornell Medicine, said it boils down to the fact that that boosters will probably cut your risk of getting sick by about 50%, and that protection probably won’t last.
“Having a booster will give you some additional protection against infection for a short term, which is always what we see with a booster, but it won’t last long. It’ll decline, and it will decline more as the more resistant variants spread,” said Moore, who was not involved in the new research.
The immunity landscape in the United States is more complex than ever. According to CDC data, roughly two-thirds of Americans have completed at least their primary series of Covid-19 vaccines. And data from blood tests shows that almost all Americans have some immunity against the virus, thanks to infection, vaccination or both.
A new preprint study from researchers at Harvard and Yale estimates that 94% of Americans have been infected with the virus that causes Covid-19 at least once, and 97% have been infected or vaccinated, increasing protection against a new Omicron infection from an estimated 22% in December 2021 to 63% by November 10, 2022. Population protection against severe disease rose from an estimated 61% in December 2021 to around 89%, on average, this November.
All of this means the US is in a better spot, defensively at least, than it ever has been against the virus – which is not to say that the country couldn’t see another Covid-19 wave, especially if a new variant emerges that is very different from what we’ve seen, if immunity continues to wane or if behavior shifts dramatically.