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Johnson & Johnson Announces Single Dose COVID-19 Vaccine Is 66 percent Effective


Dr. Alfredo Carpineti

Senior Staff Writer & Space Correspondent

clockJan 29 2021, 14:46 UTC

Image credit: M-Foto/

Hot on the heels of the Novavax COVID-19 vaccine announcement, American multinational company Johnson & Johnson has announced that its single-shot Jansen SARS-CoV-2 vaccine is 66 percent effective at preventing moderate to severe COVID-19 28 days after the vaccination, with onset protection seen as early as 14 days.

The Phase 3 trial data showed an 85 percent efficacy in preventing severe disease and complete prevention against COVID-19-related hospitalization and death. Hospitalization and death are two of the parameters used to define severe COVID-19, alongside respiratory failure, shock, organ failure, and serious health deterioration.


The advantage of this vaccine above others already approved by governments across the world is that it is administered in a single dose, making it an important tool in speeding up vaccine distribution. Its high efficacy in preventing severe disease will help prevent health services from becoming overwhelmed by serious cases.

“A one-shot vaccine is considered by the World Health Organization to be the best option in pandemic settings, enhancing access, distribution, and compliance," Dr Paul Stoffels, chief scientific officer at Johnson & Johnson, said in a statement. "Eighty-five percent 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. It also offers the hope of helping ease the huge burden placed on healthcare systems and communities.”

The phase 3 trial had 43,783 international participants, showing a 66 percent efficacy overall. The level of protection against moderate to severe COVID-19 infection was 72 percent in the United States, 66 percent in Latin America, and 57 percent in South Africa, 28 days post-vaccination. This latter group is particularly important as 95 percent of the people infected there had contracted the new South African variant of the virus, making the vaccine effective against this.


“Changing the trajectory of the pandemic will require mass vaccination to create herd immunity, and a single-dose regimen with fast onset of protection and ease of delivery and storage provides a potential solution to reaching as many people as possible," Dr Mathai Mammen, Global Head at Janssen Research & Development said. "The ability to avoid hospitalizations and deaths would change the game in combating the pandemic.”

The single-dose vaccine is estimated to remain stable for two years at -20°C (-4°F) and can be kept at temperatures of 2-8°C (36°F–46°F) for at least three months, making it easy to distribute.

The data will be submitted for peer-review in the coming weeks and the company plans to follow up with participants as well. It will file for US Emergency Use Authorization (EUA) in the same timeframe, with shipment expected to commence as soon as it is authorized.


For more information about COVID-19, check out the IFLScience COVID-19 hub where you can follow the current state of the pandemic, the progress of vaccine development, and further insights into the disease.

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