According to a JAMA article published on March 3, 2021, “there is growing optimism and hope that by virtue of ongoing immunization efforts, seasonality (declining infections through August), and naturally acquired immunity, by spring and early summer 2021 in the U.S. there will be a substantial decline in the number of deaths and hospitalizations related to COVID-19. That said, herd immunity against SARS-CoV-2 is low simply because not all individuals in the U.S. are eligible to be vaccinated and a quarter of eligible individuals will likely decline to be immunized”.
“Herd immunity is a theoretical construct from infectious disease modeling that says, in a population in which every individual is equally likely to encounter every other individual, the transmission will not be sustained when immunity through past infection, vaccination, or both reaches the level of 1/R, where R is the number of infections caused by a single infection in a population in which everyone is susceptible”.
Three key considerations will make achieving herd immunity against COVID-19 challenging:
- Vaccines will have a reduced effect on preventing infection from the B.1.351 variant.
- Not enough individuals will receive the vaccine
- There is concern about the extent to which previous infections from one variant protect individuals from reinfection with some new variants.
If new variants continue to appear, winter surges may become the norm. This prospect requires advance planning and consideration of a range of strategies to mitigate the consequences for communities and health systems. Stay informed, stay well and stay tuned!