Janssen/J&J COVID-19 Vaccine Cuts Transmission, New Data Show

Damian McNamara

February 24, 2021

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New findings suggest the Janssen/Johnson and Johnson COVID-19 vaccine can reduce the risk of an immunized person unknowingly passing along the virus to others.

The single-dose vaccine reduces the risk of asymptomatic infection by 74% at 71 days compared with placebo, according to documents released today by the US Food and Drug Administration.

"The decrease in asymptomatic transmission is very welcome news too in curbing the spread of the virus," Phyllis Tien, MD, told Medscape Medical News.

"While the earlier press release reported that the vaccine was effective against preventing severe COVID-19 disease, as well as hospitalizations and death, this new data shows that the vaccine can also decrease transmission, which is very important on a public health level," said Tien, professor of medicine in the Division of Infectious Diseases at the University of California San Francisco.

"It is extremely important in terms of getting to herd immunity," Paul Goepfert, MD, director of the Alabama Vaccine Research Clinic and infectious disease specialist at the University of Alabama, Birmingham, told Medscape Medical News. "It means that this vaccine is likely preventing subsequent transmission after a single dose, which could have huge implications once we get the majority of folks vaccinated."

The FDA cautioned that the numbers of participants included in the study are relatively small and need to be verified. However, the Johnson and Johnson vaccine might not be the only product offering this advantage. Early data suggest that the Pfizer/BioNTech vaccine also decreases transmission, providing further evidence that the protection offered by immunization goes beyond the individual.

The new analyses were provided by the FDA in advance of its review of the Janssen/Johnson and Johnson vaccine. The agency plans to fully address the Ad26.COV2.S vaccine at its Vaccines and Related Biological Products Advisory Committee Meeting on on Friday, including evaluating its safety and efficacy.

The agency's decision on whether or not to grant emergency use authorization (EUA) to the Johnson and Johnson vaccine could come as early as Friday evening or Saturday.

In addition to the newly released data, officials are likely to discuss phase 3 data, released January 29, that reveal an 85% efficacy for the vaccine against severe COVID-19 illness globally, including data from South America, South Africa, and the US. When the analysis was restricted to data from US participants, the trial showed a 73% efficacy against moderate to severe COVID-19.

If and when the FDA grants an EUA, it remains unclear how much of the new vaccine will be immediately available. Initially, Johnson and Johnson predicted 18 million doses would be ready by the end of February, but others stated the figure will be closer to 2 to 4 million. The manufacturer's contract with the US government stipulates production of 100 million doses by the end of June.

Tien received support from Johnson and Johnson to conduct the J&J COVID-19 vaccine trial in the SF VA HealthCare System. Goepfert has 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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