Johnson & Johnson published updated data on its Covid-19 vaccine on Wednesday, showing that it provided participants in a clinical trial with at least some immunity after a dose.
The data, published in the New England Journal of Medicine, offer only suggestions for a tempting question: the vaccine, given in a single injection, could perform as well as vaccines that US regulators have already authorized, which are administered in two?
In the study, participants had neutralizing antibodies, measured in a unit called the geometric mean titer, from 224 to 354, on the 29th day after the first dose of the vaccine; these levels reached 288 to 488 on day 57. These levels could be sufficient to produce immunity. But there was a great benefit in giving participants a boost. He doubled or tripled his neutralizing antibody levels. The question is whether the antibody levels induced by the first dose are in fact sufficient or whether there are other types of immunity stimulated by the vaccine that lead to protection.
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“Just because you’re higher in the neutralizing response doesn’t necessarily mean it’s more effective,” said Paul Offit, director of the Vaccine Education Center at Children’s Hospital in Philadelphia. “It may be that the immune response induced by the first dose is sufficient and that more is not necessarily better.”
The answer to the question, of course, will come from the results of Phase 3 clinical trials. Said Carlos del Rio, distinguished professor of medicine at Emory University School of Medicine: “The proof is in the pudding”.
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A third vaccine that is authorized – and that could be administered in a single dose – could help to reshape the fight against the Covid-19 pandemic, even if supplies may be limited for some time.
“Part of the complication we have is this two-dose business,” said del Rio. “If we can have a single-dose vaccine, the J&J vaccine would undoubtedly become the vaccine of choice for the world.”
There are two Phase 3 studies underway. A study of 40,000 single-dose vaccine volunteers, conducted in the United States, is due to be read in the next two weeks. A second study, equally large, is being conducted using the same vaccine administered in two doses, each administered 57 days apart, in case the vaccine is not effective in a single dose regimen or there are other advantages, such as the vaccine’s durability. , to give a second dose.
An earlier version of the article published in NEJM was released in September on a prepress server, meaning that it had not been peer-reviewed. But there is new data on the safety and durability of the vaccine in the current study, which includes information on the safety of the injection, the duration of immune responses and the effect of adding a second dose to the first.
Del Rio is optimistic. He points out that after a dose of the current vaccines – one made by Pfizer and its partner, BioNTech, and the other made by Moderna – only 60% of the participants seemed to have levels of neutralizing antibodies against SARS-CoV-2, the virus that causes Covid19. With J&J vaccine data at NEJM, he said, that number appears to be 90%. Del Rio was an investigator of the Moderna trial.
But Anna Durbin, a professor at the Johns Hopkins Bloomberg School of Public Health, was less confident about levels of protection. In particular, she was skeptical that a single dose vaccine would be sufficient for older adults, who do not always have an immune response as strong as younger ones.
“I think it was a little risky to go with the single dose, and I think it was very responsible for the company to look at a two-dose and a one-dose regimen,” said Durbin, one investigator testing Pfizer vaccine and another testing a vaccine manufactured by AstraZeneca.
Johan Van Hoof, global head of the J&J vaccines division, said that both the animal data, which showed strong protection based on a single dose, and the data made available on Wednesday, gave J&J the confidence to try a blood test. one dose. But part of the reason, he said, was the need for a single-dose vaccine in a pandemic.
The World Health Organization, said Van Hoof, points out that the ideal profile for a pandemic vaccine is different from one in normal times.
“The difference is that for use in an epidemic environment, where you go to [largest] vaccination campaign, there are huge advantages to going with a single dose, even if there is some compensation in terms of durability or protection, ”said Van Hoof.
If the test result, expected in the coming weeks, is positive, the data will be forwarded to the Food and Drug Administration, which establishes a possible emergency use authorization in February. But then there will be the question of how fast the vaccine can be manufactured. On Tuesday, in a call to reporters, Moncef Slaoui, head of the government’s Operation Warp Speed program, said the increase could take time.
He said there would be “one million digit” doses available in the second half of February and that efforts were being made to increase that number. There would be more in March and more in April, Slaoui predicted.
Johnson & Johnson said that, without regulatory approval, it is too early to offer month-to-month estimates of the number of doses available.
“We have started production of our candidate vaccine and we are confident in our ability to meet our 2021 supply commitments signed with governments, and we hope to share more details after some of these steps have been accomplished,” the company said in a statement.