J&J one-dose Covid vaccine is 66% effective, a weapon but not a knockout punch

Johnson & Johnson said Friday that its single-dose Covid-19 vaccine reduced rates of moderate and severe disease, but the shot appeared less effective in South Africa, where a new coronavirus variant has become common.

Overall, the vaccine was 66% effective at preventing moderate to severe disease 28 days after vaccination. But efficacy differed depending on geography. The shot was 72% effective among clinical trial volunteers in the U.S, but 66% among those in Latin America, and just 57% among those in South Africa. Though markedly below the levels seen with the first two authorized Covid-19 vaccines, those rates are above the thresholds originally set by the U.S. Food and Drug Administration for a vaccine to be considered useful.

The vaccine reduced severe disease alone by 85%, and prevented Covid-related hospitalization or death, Johnson & Johnson said.

“In a pandemic, if you can, with a single-dose vaccine, very quickly eliminate the severe consequences of death, hospitalization, and severe disease, that’s what’s important for society,” Paul Stoffels, the company’s chief scientific officer, told STAT.

Eric Topol, director and founder of the Scripps Research Translational Institute, called the results “disappointing,” but added that a vaccine that prevents the most serious outcomes, such as hospitalization and death, is still valuable. “It reinforces how lucky we were that the first two were more effective,” he added.

The results set off a new phase in the battle against the SARS-CoV-2 virus, which causes Covid-19. Different vaccines against the virus are proving to have varying levels of efficacy, but also distinct attributes that could make them more — or less — valuable in certain contexts.

Results from the first two authorized vaccines, one from partners Pfizer and BioNtech and a second from Moderna, were considerably stronger, reducing symptomatic infection by about 95%. But those vaccines require two doses. They also come with distribution challenges since they are required to stay at ultra-cold temperatures.

The new variant of the virus that was first identified in South Africa, B.1.351, throws another monkey wrench into the equation. It appears to make vaccines less effective. Novavax, another vaccine manufacturer, said Thursday that its vaccine was 90% effective in the U.K. but just 49% effective in South Africa. The existence of such a variant raises the possibility that vaccine makers will have to develop booster shots to protect against it. They might even need to do so regularly, as new strains of the coronavirus emerge.

The efficacy of authorized vaccines appears to be somewhat lessened by the B.1.351 strain in test-tube experiments, but have not been put to the test against it yet in clinical research.

“The policy implications of having different vaccines with different levels of efficacy are huge,” said Carlos del Rio, a  professor of infectious diseases at the Emory University School of Medicine. “To deal with this pandemic and stop the spread, I think you use all the tools in the toolbox.”

The J&J results are from an interim analysis of a study of 44,325 volunteers in which 468 symptomatic cases of Covid-19 occurred. They are being unveiled Friday morning at a press conference with the National Institutes of Health, which helped run the study as part of the U.S. vaccine effort, known as Operation Warp Speed. Because the study is still ongoing, the data could still change.

Unlike the Pfizer/BioNTech and Moderna vaccines, which are based on a new technology called mRNA that uses the body’s own cells to produce a key viral protein, the J&J vaccine uses a type of virus called an adenovirus to deliver genes that produce those same viral proteins. A similar technology was used in the vaccine developed by Oxford University and AstraZeneca.

J&J said that the trial did not result in any significant safety concerns about the vaccine. A case of stroke in one volunteer, which prompted researchers to pause the trial this fall, was determined to be unrelated to the vaccine, Stoffels said. Fevers occurred in 9% of those who received the vaccine, and fevers of more than 104 degrees occured in 0.2% of vaccine recipients. Serious adverse events were more common among those who received placebo than the vaccine.

No matter the age of volunteers in the study, the vaccine appeared to have strong efficacy, Stoffels said. There had been concerns its effectiveness might be less robust in older people.

Akiko Iwasaki, a virologist at Yale University, said that the results for both the Novavax and J&J vaccines were strong. She noted that it’s difficult to compare the J&J results to those from other trials, because the earlier trials counted cases of mild Covid-19 whereas the J&J study included only sicker ones.

Regardless, Iwasaki emphasized the importance of simply vaccinating as many people as possible, because the current lack of immunity in the majority of the population, and the high number of cases, is giving the virus an opportunity to mutate more often.

“We’ve got to get the first dose to as many people as possible,” Iwasaki said. “These variants that are more transmissible and potentially even more lethal are on the rise. I think time is really what we’re fighting against.”

Kert Viele, a statistician at Berry Consultants, made a similar point. Approving more vaccines, and expanding global supply, could mean communities reach herd immunity, in which enough people are inoculated against a pathogen to halt chains of transmission. “If we can lower global cases,” Viele said, “we will reduce the emergence rate of all of these strains to everyone’s benefit, and thus the need for such reformulations in the future.”

One hope is that the efficacy of the Johnson & Johnson vaccine could rise if it is given as a two-dose regimen. Johnson & Johnson is running another large study, enrolling 30,000 patients, testing two doses of the vaccine given 57 days apart. However, Stoffels said, waiting that long between doses will slow results. He expects results of the two-dose study to read out in the summer or fall.

The population in the study was “diverse and broad,” J&J said. Patients came from the U.S. (44%), Central and South America (41%) and South Africa (15%). Women made up 45% of the study, and men 55%. Among participants globally, 59% were white, 45% Hispanic or Latinx, 13% were Black, 6% were Asian and 1% were Native American. Volunteers had health conditions including obesity, type 2 diabetes, hypertension, and HIV.

The J&J vaccine will be far easier to distribute than the mRNA vaccines made by Moderna and Pfizer/BioNTech. The vaccine will remain stable for two years at -4 degree Fahrenheit, and will remain stable for up to three months if kept at between 36 degrees and 46 degrees Fahrenheit.

Johnson & Johnson expects to file with the FDA for an emergency use authorization in early February, and, assuming the vaccine is authorized, will have some product ready to ship immediately after getting a go-ahead. The company declined to give specifics on how much would be available, except to say it expects to make all of its 2021 supply commitments.

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