Moderna CEO warns people may need fourth Covid shot as efficacy of boosters likely to decline over time

Booster shots are playing an increasingly important role in public health strategies to control the virus, with protection from the original two shots having taken a significant blow from omicron.

Data from the United Kingdom found that Moderna and Pfizer’s two-dose vaccines are only about 10% effective at preventing symptomatic infection from omicron 20 weeks after the second dose.

The same study, published by the U.K. Health Security Agency, found that booster doses are up to 75% effective at preventing symptomatic infection two weeks after receiving the shot.

However, the efficacy of booster shots starts to decline after about four weeks, according to the study. Boosters were 55% to 70% effective at preventing infection at weeks five to nine, and 40% to 50% effective 10 weeks after receiving the shot.

Pfizer CEO Albert Bourla told CNBC last month that people will likely need a fourth dose, and the shot may be needed sooner than expected due to omicron’s virulence.

Bancel, during the Goldman Sachs interview, said omicron could accelerate the transition from the acute crisis caused by the virus to an endemic phase where enough people have immune protection so that Covid isn’t as disruptive to public life.

However, he also cautioned against predictions, noting that omicron, with its dozens of mutations, took most of the scientific community by surprise. The data so far indicates that omicron is more transmissible but less severe than past strains.

However, a random mutation could change the course of the pandemic again, Bancel said.

“What is totally impossible to predict, is there a new mutation coming in a day, a week, three months that is worse in terms of severity of disease,” he said. “That’s a piece that we’ll have to just be cautious about.”