Scientists break ground on Omicron's effect on vaccines and boosters

A wave of panic swept over SA and the globe when the Omicron variant was recently announced along with news that mutations at the spike protein might affect the efficacy of existing vaccines.

But this week, two important studies revealed their findings.

The first study has shown that a booster dose of the Johnson and Johnson vaccine, which officially had a single dose regimen in SA, is 84% effective at preventing hospitalisation.

Single doses were administered to health workers between February and May this year under the Sisonke study, and then, between November 15 and December 20, about 69,000 health workers were given a booster shot.

The study’s co-lead investigator Linda-Gail Bekker told Reuters: “It reassures us that Covid-19 vaccines continue to be effective for the purpose for which they were designed, which is to protect people against severe disease and death.”

The study is still awaiting peer review, but is a feather in the cap of research as Omicron spreads fast and furiously across the globe.

Said Bekker: “This is yet another piece of evidence that we have not lost that impact even in the face of a very mutated variant.” 

The results of the study have come exactly a week after the department of health announced that it would be rolling out the J&J booster shots after getting the go-ahead from the South African Health Products Regulatory Authority (Sahpra).

Foster Mohale, on behalf of the department, confirmed the rollout of the boosters to the general population, and not just health workers, beginning on the day before Christmas.

Another study focused on the Pfizer vaccine after it too was under scrutiny in light of the Omicron variant.

According to a paper published in the New England Journal of Medicine, between mid-November and December 7, those who had received a double dose of the Pfizer shot had a 70% chance of staying out of hospital.

This was down from the high of 93% during the previous wave when Delta was the dominant variant.

The study was based on more than 211,000 Covid-19 infections of which 78,000 were caused by Omicron.

The researchers, including Gail-Bekker, used data from Discovery Health.

Discovery’s clinical and actuarial teams, along with scientists from the South African Medical Research Council, said, “We saw a maintenance of effectiveness of the BNT162b2 [Pfizer] vaccine [albeit at a reduced level] against hospital admission for Covid-19 that was presumed to have been caused by the Omicron variant as compared with the rate associated with the Delta variant earlier in the year.”

They also said, however, that “the addition of a booster dose of vaccine may mitigate this reduction in vaccine effectiveness”.

The health department began administering booster doses of Pfizer last Friday after giving the green light at the same time as the Johnson and Johnson boosters.

The booster in the case of Pfizer comes in the wake of a two-dose regimen in the country and is given six months after the administration of the second dose.

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