According to the CDC, people are not up to date with COVID-19 vaccinations if they're not boosted 5 months after the second dose of Pfizer and Moderna vaccines or 2 months after the J&J jab. With this fast-waning vaccine-induced immunity, some countries like Israel are already up to their fourth shot (booster doses) in just over a year since the first vaccine rollout. Scientists are asking, is this frequent boosting strategy the right way to go? Short answer: If these boosters continue to be based on the original strain, no.
Examining Israel, they're up to their fourth shot because they had one of the highest daily infection rates in the world during the Delta outbreak despite being one of the most highly vaccinated countries. According to Nature, third shots provided a little extra protection from infection with Omicron. And whether four shots are any better at increasing infection-blocking antibodies than three shots isn't yet certain.
Boosters do increase levels of neutralizing antibodies that block infection by preventing the virus from entering cells, but this effect doesn't last long enough. Real-world data from the UK from late 2021 suggest booster-induced immunity wanes faster against Omicron compared to Delta. It also appears boosters might be needed on an ongoing basis just to protect against severe illness and hospitalization, especially if future variants aren't milder - real-world data from the US, UK and Israel showed that boosters were good at preventing severe illness and decreasing chances of hospitalization in most people for only up to 5 months with Delta and for 3 or more months with Omicron.
As Danny Altmann, an immunologist at Imperial College London, puts it, “We’ve stumbled into a de facto program of frequent mRNA boosters as an emergency measure, but this really doesn’t feel like the way to go.”
On January 11, the World Health Organization warned that giving repeated booster doses of the original vaccine isn't appropriate or sustainable. A better approach, according to Miles Davenport, a computational immunologist at the University of New South Wales in Syndey, Australia, would be to create a pan-coronavirus vaccine based on multiple past variants and predicted future strains.
Omicron-specific vaccines are currently underway until scientists become more confident at predicting the virus's evolution to predict future strains for a pan-coronavirus vaccine. “At some point, inevitably, we’re going to have to make variant vaccines — if vaccines are the way population immunity will be maintained — but we’re not at the point where we can confidently predict the evolution of the virus,” says Paul Bieniasz, a virologist at the Rockefeller University in New York City.
Infectious disease specialists recommend that current vaccines be used with the intent to protect against severe illness, that vulnerable groups be boosted and that antivirals be used to keep people out of the hospital.
Sources: CDC, Nature, Nature, NPR
