Johnson & Johnson published updated early data on its Covid-19 vaccine on Wednesday, showing that it provided participants in a clinical trial with at least some immunity after one dose.
The data, published in the New England Journal of Medicine, gives only an indication of a tantalizing question: can the vaccine, given in a single shot, as well as the vaccines approved by U.S. regulators, export as two be given?
In the study, participants had neutralizing antibodies, measured in a unit called a geometric mean titer, from 224 to 354, on day 29 after their first vaccine dose; these levels reached 57,288 to 488 by day. These levels may be enough to bring about immunity. But there was a big benefit to giving the participants a dose. It doubled or tripled their levels of neutralizing antibodies. The question is whether the antibody levels caused by the first dose are indeed adequate, or whether there are other types of immunity stimulated by the vaccine that lead to protection.
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“Just because it’s a higher neutralizing response does not necessarily mean it is more effective,” said Paul Offit, director of the Center for Vaccine Education at the Children’s Hospital of Philadelphia. “It may be that the immune response caused by the first dose is sufficient and that more is not necessarily better.”
The answer to the question, of course, comes from phase 3 clinical trials. Carlos del Rio, a leading professor of medicine at the Emory University School of Medicine, said: “The proof is in the pudding.”
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A third authorized vaccine – and one that can be administered in a single dose – could help reform the fight against the Covid-19 pandemic, even if the supply is expected for some time.
“Part of the complication we have is this two-dose deal,” del Rio said. “If we can have a single vaccine, then the J&J vaccine will undoubtedly become the choice for the world.”
There are two phase 3 studies being conducted. A study of 40,000 volunteers of the one-dose vaccine, conducted in the US, is being read out over the next two weeks. A second, equally large study is performed with the same vaccine given as two doses, each administered 57 days apart, in case the vaccine does not appear to be effective in a single dose regimen, or if there are other benefits, such as durability of the vaccine, to give a second dose.
An earlier version of the article published in NEJM was released on a preprint server in September, meaning it has not yet been rated by the peer. But there is new information about the safety and durability of the vaccine in the current article, which contains information about the safety of the shot, 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 one dose of the current vaccines – one made by Pfizer and its partner, BioNTech, and another by Moderna – only 60% of participants apparently have antibody levels against SARS-CoV-2, the virus that causes , neutralize. Covid19. With J&J vaccine data in NEJM, he said, it appears the figure is 90%. Del Rio was an investigator in the Moderna trial.
But Anna Durbin, a professor at the Johns Hopkins Bloomberg School of Public Health, was less confident about the levels of protection. In particular, she was skeptical that a single-dose vaccine would be enough for older adults, who do not always have such a strong immune response as younger people.
“I think it was a bit risky to go along with the single dose, and I think it was very responsible for the company to look at a two-dose regimen and a single-dose regimen,” Durbin said. one investigator in trials with the Pfizer vaccine and another testing a vaccine made by AstraZeneca.
Johan Van Hoof, the world head of J & J’s vaccines division, said that both animals’ data, which showed strong protection based on a single dose, and data made available on Wednesday, gave J&J confidence to have a try a dose. But part of the reason was the need for a single-dose vaccine in a pandemic.
The World Health Organization, Van Hoof said, points out that the ideal profile of a pandemic vaccine is different from one during normal times.
‘The difference there is that it is used in an epidemic environment [largest] vaccination campaigns, there are great benefits associated with a single dose, even if there is ultimately a compromise in terms of durability or protection, ‘Van Hoof said.
If the trial result, which is expected in the next few weeks, is positive, the data will be submitted to the Food and Drug Administration, which will introduce a possible authorization for emergency use in February. But then there will be the question of how fast the vaccine can be manufactured. Moncef Slaoui, the outgoing head of the government’s Operation Warp Speed program, said in a call with reporters on Tuesday that the run-up could take time.
He said that in the second half of February doses would be available for a single digit million, and that an attempt was being made to increase the number. There would be more in March, and much more in April, Slaoui predicts.
Johnson & Johnson said that, without regulatory approval, it is too early to offer monthly estimates on the amount of doses available.
“We have begun production of our vaccine candidate and are confident in our ability to meet our 2021 government-committed supply commitments, and we expect to share more details after some of these steps are taken,” he said. the company said in a statement.