With coronavirus mutations pitted against vaccinations in a global arms race, we may never go back to normal.

For the past year, an assumption — sometimes explicit, often tacit — has informed almost all our thinking about the pandemic: At some point, it will be over, and then we’ll go “back to normal.”

This premise is almost certainly wrong. SARS-CoV-2, protean and elusive as it is, may become our permanent enemy, like the flu but worse. And even if it peters out eventually, our lives and routines will by then have changed irreversibly. Going “back” won’t be an option; the only way is forward. But to what exactly?

Most epidemics disappear once populations achieve herd immunity and the pathogen has too few vulnerable bodies available as hosts for its self-propagation. This herd protection comes about through the combination of natural immunity in people who’ve recovered from infection and vaccination of the remaining population.

In the case of SARS-CoV-2, however, recent developments suggest that we may never achieve herd immunity. Even the U.S., which leads most other countries in vaccinations and already had large outbreaks, won’t get there. That’s the upshot of an analysis by Christopher Murray at the University of Washington and Peter Piot at the London School of Hygiene and Tropical Medicine.