As Omicron Rises, Fourth Dose of COVID-19 Vaccine May be Needed

As the debate about whether a third dose of COVID-19 vaccine (or a booster shot) might seem to have been settled—at least among medical experts (get the booster) if not among enough of the public (don’t tell me what to do)—a new debate begins thanks to the Omicron variant.

Pfizer CEO Albert Bourla tells CNBC that a fourth COVID-19 shot may be needed because the unusual mutations on the Omicron variant could weaken the vaccine antibodies. This is not exactly news, just an update on a statement Bourla recently made when he said a fourth shot might be needed about a year after the third (or booster) shot.

“With omicron we need to wait and see because we have very little information. We may need it faster,” Bourla told CNBC.

Bourla’s statement comes as US public health officials weigh whether to make the definition of fully vaccinated equal to having 3 doses of either the Pfizer/BioNTech or Moderna vaccines.

Anthony Fauci, MD, the director of the National Institute of Allergy and Infectious Diseases and the chief White House medical advisor, said on Wednesday that it’s a matter “of when, not if” the definition of fully vaccinated changes.

“I don’t see that changing tomorrow or next week, but certainly if you want to talk about what optimal protection is, I don’t think anybody would argue that optimal protection is going to be with a third shot,” Fauci said.

Scientists are still trying to work out the implications of Omicron. A study released this week by BioNTech indicates that a third dose of their vaccine is as efficacious against Omicron as two doses were against earlier variants of the disease.

At a press conference Wednesday, Özlem Türeci, MD, BioNTech's chief medical officer, said that the “first line of defense with two doses of vaccination might be compromised [by Omicron], and three doses of vaccination are required to restore protection.”

At the same press conference, BioNTech CEO Uğur Şahin, PhD, (and Türeci’s husband) said that Pfizer/BioNTech are developing a vaccine that would be targeted at Omicron. Mass production could begin as early as March, he said.

The statements by Bourla, Türeci, and Şahin came with the release of lab results conducted by Pfizer/BioNTech that show that that serum antibodies induced by their COVID-19 vaccine neutralized the Omicron variant after 3 doses. Sera obtained from vaccines 1 month after receiving the booster vaccination neutralized the Omicron variant to levels that are comparable to those observed for the wild-type SARS-CoV-2 spike protein after 2 doses.

The results come with a caveat, however. As Bourla noted, the vaccine was tested against Omicron that had been manufactured in the laboratory. Results of how the vaccine acts in the real world should be available within 2 weeks.

Bourla told CNBC that “when we see real-world data, [that] will determine if the omicron is well covered by the third dose and for how long…. I think we will need a fourth dose.”

Eric Topol, MD, director of the Scripps Research Translational Institute in California, told USA Today that the Pfizer/BioNTech lab results provide “reassurance that booster shots can achieve solid vaccine effectiveness against Omicron, but we don’t know how durable that will be.”

The Pfizer/BioNTech studies are the first to show that the vaccines will work at least to some degree against Omicron. Researchers reached that conclusion by examining data from blood samples of 20 people who’d gotten their second dose three weeks prior, or a booster shot four weeks earlier. Those who’d had three doses had higher levels of COVID-19 fighting antibodies than those who’d had two. Pfizer/BioNTech noted when it released the study results that the bottom line is that their vaccine protects against Omicron.

But the question remains: for how long?