How well does the Covid-19 booster protect against Omicron?

With Omicron still causing hundreds of thousands of new Covid-19 cases each day, it’s understandable that, for some people, getting infected is starting to feel inevitable. Getting a Covid-19 booster may be the best thing you can do to protect yourself. 

Vaccines are the best way to prevent severe Covid-19 outcomes like hospitalisation and death. But research also shows that vaccine protection may wane over time. Enter the need for a third dose to boost antibody levels back up. 

As the Omicron variant began to surge, it became especially clear that two doses may not be enough to keep you from getting the highly contagious variant. In December, vaccine makers Pfizer and BioNTech released research that found that while two doses of the vaccine still offered protection against “severe forms of the disease,” they were significantly less effective at preventing infection. 

As Omicron has continued to spread – it’s now responsible for 99.9% of all Covid-19 infections in the US, per CNN – scientists have been working to figure out just how well the Covid-19 booster protects against mild infections as well as severe COVID outcomes. This week, vaccine maker Moderna published a new study in the New England Journal of Medicine, which found two important things: Six months after the booster shot, antibody protection had waned, but ultimately it was still effective in protecting against the virus. 

Moderna’s study found, similar to the results of the Pfizer BioNTech study, that anti-COVID antibodies waned significantly in the months after the second vaccine dose. In analysing blood samples of people who received the Moderna vaccine, researchers found that antibody levels capable of neutralising Omicron were found in 85% of people a month after their second dose. But by seven months, neutralization of Omicron was found in only 55% of people. Getting a third dose turned things around somewhat. Researchers reported a 20-fold increase in Omicron-neutralising antibodies a month after the booster. 

But did the booster protection eventually wane as well? It did, according to the study, but not by as much. Six months after the booster shot, antibody protection was just over six times lower than after it was first administered – something researchers expected. 

“This is not uncommon, for mRNA vaccines or for vaccines in general,” Dave Montefiori, PhD, a professor in Duke University’s department of surgery and co-author of the Moderna study, told CNN. “Antibodies go down because the body figures it does not need to maintain them at that high level. It doesn’t mean there is no protection. There is immunologic memory.” To that point, another lab study from Pfizer, which was published earlier this week, found that four months after a booster dose, antibody levels were still high enough to protect against Omicron, The Washington Post reported. 

Despite all of this, only 67% of the eligible population in the US is fully vaccinated (which the Centers for Disease Control and Prevention currently defines as having received two primary doses of the Pfizer or Moderna vaccines or one shot of the single-dose Johnson & Johnson vax), according to the CDC. And of those vaccinated people, only 40% have gotten their booster. 

What this new research means for the future of vaccines is still unclear. Will we be getting Covid-19 boosters indefinitely? Will we eventually need variant-specific vaccines? The Pfizer and Moderna studies may be “an early sign that at some interval down the road, as we get over this pandemic and get to a truce with this virus, that we may well have to get a periodic booster in order to maintain protection,” William Schaffner, M.D., medical director of the National Foundation for Infectious Diseases, told CNN. 

But vaccine makers are also currently preparing for the latter possibility. Earlier this week Pfizer and BioNTech announced that they’d begun a clinical trial of an Omicron-specific vaccine, which is already in production. And Moderna announced yesterday that they’ve begun their own phase two clinical trial of an omicron vaccine. “We are reassured by the antibody persistence against omicron at six months after the currently authorized 50 μg booster of mRNA-1273. Nonetheless, given the long-term threat demonstrated by omicron’s immune escape, we are advancing our omicron-specific variant vaccine booster candidate,” Moderna CEO Stéphane Bancel said in a news release, per CNN. 

So what does this all mean for your vaccine status? The research is clear: Getting vaccinated is an important way to protect yourself against a severe case of Covid-19 – getting boosted is an even better way, and may offer more protection against getting even a mild case.

This article was first published on SELF.