Almost since the beginning of the Covid-19 pandemic, epidemiologists, policymakers, science journalists, and many more have held onto two general assumptions that give them hope: that eventually enough people might develop immunity to Covid-19 to slow down transmission and that even if Covid doesn’t fade away, it might become a more seasonal illness, like respiratory viruses such as the flu, RSV, and other bugs—even other coronaviruses. But now, as cases rise steeply and summer approaches, Covid is again taking us by surprise.
There were some early signs that Covid might be different: While previous waves have reached their greatest peaks in winter, the virus also did significant damage in other seasons. And now, with the omicron wave, even more evidence is accumulating. While we’ve had two relatively calmer summers with regional spread, the relaxation of measures across the country seems to have triggered another surge, with nearly every state seeing an increase in Covid cases and hospitalizations.
“The wild card is the rise of variants,” Marc Lipsitch, professor of epidemiology at Harvard’s T.H. Chan School of Public Health, told me over a year ago, when I asked him to predict what Covid would look like in 2022. How fast the virus would evolve would determine much about the next few years. Since then, variants have arisen that can evade our immune protections with startling efficiency. Even those who already suffered from cases of the first omicron variant in January or February are now reporting new cases of BA.2 or BA.2.12.1, two omicron subvariants in the United States that have quickly risen to dominance. While back in November 2020, one study suggested people who contracted Covid-19 and recovered might be immune to reinfection for years or even decades, it’s now clear that won’t be the case because of rapidly changing variants. People who recover from Covid-19 now can be reinfected in a matter of months.