J&J Vaccine 85% Efficacious Against Severe COVID Globally

Damian McNamara

January 29, 2021

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The Janssen/Johnson & Johnson single-dose adenovirus vaccine provides 85% efficacy globally against severe COVID-19 illness, and it is 72% efficacious against moderate-to-severe illness in the US, according to highly anticipated interim Phase 3 results announced this morning.

The efficacy against severe disease provided by the Janssen/J&J vaccine held true regardless of age, race/ethnicity, absence or presence of comorbidities, and geography. The 44,000-participant ENSEMBLE study was conducted in the United States, South America, and South Africa.

"My overall take is that the 70 plus percent efficacy in the US for a single shot vaccine is great," Robert Atmar, MD, professor of infectious diseases at Baylor College of Medicine in Houston, told Medscape Medical News.

"If we had said a year ago that we'd have a vaccine that was 70% efficacious, we would have been more than happy with that result. And it has the significant advantage of being a single injection and being easier to ship," he added. "So that to me is the good news."

The overall efficacy against moderate to severe SARS-CoV-2 28 days post-vaccination was 66% globally, 72% in the United States, 66% in Latin America, and 57% in South Africa, officials from the National Institutes of Health and Janssen reported during a media briefing.

"The reason for differences in efficacy in different geographic areas does likely largely reflect what [variant] was circulating in those areas," Atmar said.  

Circulating virus variants are vexing many officials. "The team is very diligently monitoring all the variants that come up, and there are literally thousands of these. We are acting in anticipation of a variant being a potential problem," said Mathai Mammen, MD, PhD, global head, Janssen Research & Development. 

"The South African variant we too acted on right away. So we too are preparing that antigen for testing. With data today, we do see that not a single South African, after 28 days post-vaccination, ended up needing to go to the hospital, no South African died who was vaccinated. We do see that 85 plus percent protection in South Africa against severe disease. That is one of the most exciting results in the dataset today," Mammen added.

Atmar said efforts are underway to stay one step ahead of the variants if possible. "We are already discussing, even with the Moderna and Pfizer vaccines, boosters and how to enhance protection against some of these variant strains. The same questions will be asked with this vaccine."

The J&J vaccine has potential advantages over the existing two-dose Pfizer/BioNTech and Moderna mRNA vaccines because it's single-dose and has less stringehe addednt storage requirements — only regular refrigeration is needed versus a need to freeze the two-dose Pfizer/BioNTech and Moderna COVID-19 vaccines. The J&J vaccine can be refrigerated for up to 3 months at 36°-46°F (2°-8°C).

But the difference between these just-released efficacy figures and the 94% to 95% efficacy provided by the existing Pfizer/BioNTech and Moderna mRNA vaccines generated many questions during the briefing.

Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases, said the focus should not just be on the overall numbers. "The most important thing from a public health standpoint domestically is to keep people out of the hospital and prevent them from getting severe illness," he said. "Many in the general public might look at a number and want to know if they get symptomatic disease or not."

"More important than preventing someone from getting some aches and a sore throat is to prevent people — particularly people who have underlying conditions and the elderly, the ones most susceptible to a severe outcome — [from getting] severe disease," Fauci added. Prevention of severe outcomes in a high percentage of individuals "will alleviate so much of the stress, human suffering, and death."

Fauci acknowledged that many people will naturally focus on the distinction between 72% efficacy and 94% to 95% efficacy. "This could be a messaging challenge...[but] you have to make sure people understand the implications."

It is more complex, he added, than just asking people: "If you go to the door on the left, you get 94% or 95%. If you go to the door to the right, you get 72%. What door do you want to go to?"

Instead, the messaging should be that "this and the other vaccines we have actually preventing severe disease to a very substantial degree."

"We need to see more of the data," Atmar said. "The level of antibody induced by a single injection of the J&J vaccine is somewhat lower than what has been reported for the Moderna and Pfizer vaccine."

"Potentially it's a small price to pay to overcome issues with cold chain [distribution requirements] and achieve still high levels of protection against disease with a single shot vaccine," he added.

Company Defends Numbers

Janssen defended their efficacy findings, pointing out that it is not a fair comparison.

"The vaccine programs that went a couple of months ago, they ran their studies during different times, when the pandemic was less complex. There were not these variants and there was not the same level of incidence, which puts pressure on vaccine efficacy," said Mammen.

"So the numbers cannot really be compared, and that does pose a messaging challenge," he said. "But the reality is if one was to run the same studies [for the Pfizer and Moderna vaccines] today you would likely see different results."

Asked if the efficacy figures could affect vaccine hesitancy, NIH Director Francis Collins, MD, PhD, said at the announcement that most reluctance among people to get vaccinated against SARS-CoV-2 stems from concerns about safety. "The safety record is extremely good for this vaccine, as it is for the others who have received emergency use authorization."

Janssen/J&J plans to submit for emergency use authorization from the US Food and Drug Administration next week, at which point the company plans to release more information of side effects, deaths, patient subpopulation efficacy, and more from the ENSEMBLE trial.

Janssen is aiming to provide 1 billion doses by the end of this year.

"We should be happy with the 70-plus percent, but by comparison it wasn't quite as high as what was described for Moderna and Pfizer. And we still don't really know what the reasons for that are," Atmar said. "Like so much more in this COVID pandemic, we have much more to learn."

Atmar conducts NIH-sponored vaccine research but disclosed no relevant financial relationships.

Damian McNamara is a staff journalist based in Miami. He covers a wide range of medical specialties, including infectious diseases, gastroenterology, and critical care. Follow Damian on Twitter: @MedReporter.

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