Herd immunity to Covid-19 could come and go, scientists say. Or we might never reach it at all. Here are some of the obstacles to achieving and maintaining it.
Young People
Very few people younger than 16 will get a Covid-19 vaccine soon. Dr. Anthony Fauci — director of the US National Institute of Allergy and Infectious Diseases — has said younger Americans will likely have to wait until early 2022 for vaccines.
And that’s a major obstacle to herd immunity. Young people may not get very sick from Covid-19 in high numbers, but they can still get infected and transmit the virus.
Anti-vaxxers
According to the Kaiser Family Foundation COVID-19 Vaccine Monitor, 20% of people surveyed in the US said they definitely would not get vaccinated or would only get vaccinated if their job or school required it.
If not enough people are willing to get vaccinated, herd immunity isn’t achievable. And if that happens, the virus will have ample opportunity to spread.
Variants
If the virus keeps spreading, replicating itself in new people, it has more opportunities to mutate. And if there are significant mutations, new and more dangerous variants could emerge.
This could also mean that drug companies have to keep updating their vaccines to be effective against new variants, and it’s not guaranteed that every vaccine will be successful against new variants.
Immunity could wear off
Dwindling immunity — either from previous infection or from vaccination — could be another reason the US could slip in and out of herd immunity. Scientists don’t know yet how long immunity from vaccines might last. So people may need to get booster shots in the future, or annual shots that can work against new variants. That’s how the yearly flu shot works.