The idea of gaining "herd immunity" against COVID-19, meaning enough people will eventually be immune to SARS-CoV-2 to stop it from spreading, is starting to look unlikely, according to Nature.
"We're moving away from the idea that we'll hit the herd-immunity threshold and then the pandemic will go away for good," said epidemiologist Lauren Ancel Meyers, PhD, mathematical biologist and executive director of the University of Texas at Austin COVID-19 Modeling Consortium.
"The vaccine will mean that the virus will start to dissipate on its own," Dr. Meyers said, but as new variants arise and immunity from infections potentially wanes, "we may find ourselves months or a year down the road still battling the threat, and having to deal with future surges."
Here are five reasons why scientists are contemplating a new normal that doesn't include herd immunity:
1. It's unclear whether vaccines prevent transmission.
2. Vaccine rollout is uneven.
3. New variants change the herd-immunity equation.
4. Immunity might not last forever.
5. Vaccines might change human behavior.