Pfizer and Moderna say Covid-19 vaccine protection wanes over time

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Pfizer and Moderna said that protection from their Covid-19 vaccines can wane over time, as the US drug regulator prepares to consider whether to approve a booster programme.

Ahead of a crucial meeting of the Food and Drug Administration vaccines advisory committee on Friday to discuss its booster proposal, Pfizer submitted a study on Wednesday by Kaiser Permanente Southern California suggesting vaccine efficacy wanes over time naturally, “irrespective of variant”, rather than as a consequence of the Delta strain evading its jab.

Pfizer presented data showing how the vaccine’s protection declined six to eight months after the second dose, becoming gradually less effective in two-month intervals. Vaccine efficacy fell about 6 per cent every two months after the second dose, down from 96.2 per cent a week after full vaccination to 83.7 per cent more than four months later.

The company also cited Israeli data showing that a third booster shot restored protection up to 95 per cent against Covid-19, documents filed to the FDA show.

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Separately, Moderna shared data on Wednesday also showing the protection afforded by its vaccine wanes over time.

“The increased risk of breakthrough infections in . . . participants who were vaccinated last year compared to more recently illustrates the impact of waning immunity and supports the need for a booster to maintain high levels of protection,” said Stéphane Bancel, Moderna chief executive.

The FDA’s advisory committee will meet on Friday to decide whether to recommend that the regulator authorise a booster dose of the BioNTech/Pfizer jab, and for which populations. The FDA has already signed off on booster doses of mRNA vaccines made by Pfizer and Moderna for people with weak immune systems.

Documents published by the FDA show Pfizer has asked regulators to approve a booster shot six months after people receive their second jab. 

In a separate assessment of data from Pfizer’s vaccine, the FDA said waning antibody levels among vaccinated people might have been linked to the jump in cases seen over the summer as the Delta variant has spread.

But officials said that the data was not conclusive on whether the vaccine’s ability to stop symptomatic infection declined, a sign of internal frictions within the regulator about whether boosters are needed.

“Overall, data indicate that currently US-licensed or authorised Covid-19 vaccines still afford protection against severe Covid-19 disease and death in the United States,” the agency said in a briefing document also published on Wednesday.

The Biden administration has said it wants to begin rolling out a vaccine booster programme next week alongside a dozen other nations that are concerned about a rise in breakthrough infections among vaccinated people.

The plan has proved controversial and attracted criticism from two top US scientists, who recently announced their retirement from the US drugs watchdog.

Those scientists, Philip Krause and Marion Gruber, co-authored a report this week that concluded there was not enough evidence to justify a booster programme at a time when vaccine supplies remain tightly constrained in other parts of the world.

Angela Hwang, president of Pfizer Biopharmaceuticals Group, said that available data supported a booster programme to protect the public and help bring an end to the pandemic sooner rather than later.

“Big picture, boosting is important, boosting is necessary. It is the way that we need to protect individuals and the public,” she said at the BofA Global Healthcare investor conference on Wednesday.

While the Biden administration prepares to decide on whether to give the final go-ahead to the booster plan, the US president is also trying to jump-start the country’s flagging vaccination rate.

Biden is due to meet business leaders at the White House on Wednesday as he looks to drum up corporate support for his administration’s new vaccine mandates. The meeting is intended to display strong backing for his move to require medium-sized and large businesses to insist their staff are either vaccinated or get tested for Covid-19 at least once a week.

Attendees include Bob Chapek, chief executive of Disney; Brad Smith, president of Microsoft, and Joshua Bolten, head of the Business Roundtable.