Johnson & Johnson’s Janssen Pharmaceutical Companies announced on Jan. 29 that its one-shot COVID-19 vaccine is 66% effective in protecting against disease, but 85% effective against preventing severe disease—results that could make it especially valuable in the effort to vaccinate parts of the world with weak health care systems.
By comparison, the vaccines already authorized in the U.S.—one from Moderna and one from Pfizer-BioNTech—each require two doses, spaced three to four weeks apart. Janssen’s vaccine can also be stored in normal refrigerators, unlike Moderna’s and Pfizer-BioNTech’s, both of which need to be frozen. While the vaccines from Moderna and Pfizer-BioNTech are around 94%-95% effective in protecting against COVID-19, that’s after two doses of those shots, which are based on mRNA, a relatively new vaccine platform. Janssen’s vaccine relies on a more traditional approach: it uses a harmless human cold virus to deliver a SARS-CoV-2 gene to the human immune system, which then learns to protect the body against COVID-19. (SARS-CoV-2 is the virus that causes COVID-19.)
“A one-shot vaccine is considered by the World Health Organization to be the best option in pandemic settings, enhancing access, distribution and compliance,” said J&J Chief Science Officer Dr. Paul Stoffels in a statement. “85% efficacy in preventing severe COVID-19 disease and prevention of COVID-19-related medical interventions will potentially protect hundreds of millions of people from serious and fatal outcomes of COVID-19.”
The J&J results came a few days after Maryland-based Novavax reported that, in a Phase 3 trial, its vaccine was nearly 90% effective in protecting against COVID-19 disease. Those results are especially reassuring since that study was conducted among 15,000 people in the U.K., where a new mutant variant of SARS-CoV-2 is quickly gaining hold. The high efficacy suggests that people vaccinated with the Novavax shot, which is based on another proven technology of injecting proteins made by SARS-CoV-2 to stimulate an immune response, can expect good protection against that new variant.
Dr. Paul Goepfert, director of the Alabama Vaccine Research Clinic at the University of Alabama and a lead investigator on the Janssen study, says he believes that the efficacy of the Janssen vaccine, particularly against emerging variant strains, justifies using it as soon as possible, and potentially boosting with an additional dose if studies support such a move. Confronting a rapidly mutating virus requires vaccinating as many people as possible as quickly as possible, Goepfert said—sentiment echoed by National Institute of Allergy and Infectious Diseases head Dr. Anthony Fauci during a Jan. 29 briefing. “Viruses can’t mutate if they can’t replicate,” Fauci said. “So we need to keep doing what we are doing, namely intensify our ability to vaccinate as many people as possible, as quickly as possible.”
The efficacy of Janssen’s vaccine, while lower than that of Moderna’s and Pfizer-BioNTech’s versions, is likely still enough for authorization in most countries. Before the studies on the first vaccines were completed, for example, the U.S. Food and Drug Administration, set a minimum threshold of 50-60% effectiveness to consider the shots for authorization. Moderna and Pfizer-BioNTech, the first two companies to report vaccine test results, far exceeded that and set a high bar. But Goepfert says it’s not a fair comparison.
“We should not just look at the [Janssen results] and say that it didn’t work very well. That’s not the important takeaway here,” Goepfert says. “The Moderna and Pfizer studies were done at a time when the virus hadn’t mutated that much. And you have to remember that Janssen’s effectiveness is after one dose, compared to two doses of Moderna and Pfizer.”
In the Janssen study, which involved more than 43,000 people in eight countries—the U.S., Argentina, Brazil, Chile, Columbia, Mexico, Peru and South Africa—the single shot was 66% effective in protecting against moderate to severe COVID-19 disease, and 85% effective in protecting specifically against severe disease about one month after injection. The effectiveness varied by country—in the U.S., the study showed the vaccine was 72% effective in protecting against moderate to severe COVID-19 disease, but 66% in Latin American countries and 57% in South Africa.
Those differences could reflect the rise of different mutant strains of SARS-CoV-2 around the world. In the study, most of the cases of disease in South Africa, for example, were caused by the mutant virus, which scientists have said shows signs of becoming resistant to the already-authorized vaccines. Janssen’s vaccine targets the spike protein that SARS-CoV-2 uses to attach to and infect human cells, and the variant circulating in South Africa has changed its genetic structure so that it attaches in a slightly different way. That means immune defenses like antibodies that are generated by vaccines and designed to block the original spike protein might not be as effective at blocking the variant.
Still, Janssen’s study shows that the vaccine-induced immunity was enough to protect against COVID-19 disease, and perhaps more importantly, protect against death after infection. The study was conducted in collaboration with scientists from the NIAID and the Biomedical Advanced Research and Development Authority of the U.S. Department of Health and Human Services, and will continue to follow participants for two years. Goepfert says that the company is also studying a two-dose regimen as well to see if it can boost immune protection even further.
Testing the already-authorized COVID-19 vaccines, as well as future vaccines, against emerging mutations will be a priority for scientists and regulators. So far, Moderna, Pfizer-BioNTech and Novavax report that tests with blood taken from people vaccinated with their shots show they’re capable of neutralizing the U.K. and South Africa variants, although Moderna and Novavax found that recipients produced fewer antibodies against the South African strain. Still, all of the studies show the immune response generated by the vaccines remains strong enough to protect against disease.
Staying on top of new mutations in the virus is a priority for the U.S. Centers for Disease Control and Prevention, said the agency’s director Dr. Rochelle Walensky during the Jan. 29 briefing. The CDC is expanding its viral sequencing efforts by working with government, academic and commercial partners to collect more samples from COVID-19 patients and genetically sequence the virus they contain in order to monitor changes in the viral genomes that might signal impending resistance to vaccines or drugs. “We’re asking surveillance from every state, about 750 samples per week, and with collaborations with university we hope to make that thousands per week,” she said.
Janssen plans to submit a request for emergency use authorization in the U.S. and elsewhere. If authorized, it will be up to global health leaders to decide if the convenience of administering the single dose, and its ability to be stored under refrigerated conditions, is enough to justify the lower overall efficacy of Janssen’s shot.