Many people who received a single dose of Johnson & Johnson Covid-19 vaccine in an early clinical trial developed neutralizing antibodies against the virus by day eight, and by day 57, all volunteers had, according to a study published Thursday in Journal of the American Medical Association.
The US Food and Drug Administration approved the Johnson & Johnson single-dose Covid-19 vaccine in February. This is one of the first peer-reviewed studies to show how the single dose of J&J vaccine worked in humans – and it worked well.
The company published data throughout the testing process. In January, J&J also published the interim results of a larger portion of the vaccine study in the New England Journal of Medicine. This study showed that the vaccine is safe and generated an immune response.
For this part of the early-stage study, Boston Beth Deaconess Medical Center in Boston recruited 25 adult volunteers who were randomized to five different groups. One group received one blow, another received two. In these two groups, the scientists tried two different doses of the vaccine. Another group received a placebo.
The scientists checked the level of antibody volunteers throughout the study. For the purpose of this study, they reported total results after 71 days. The company will follow these volunteers for two years.
For volunteers who received the vaccine, the researchers found that about 90% of those who received the vaccine developed antibodies to the coronavirus by the eighth day. On day 57, all volunteers who received the vaccine developed neutralizing antibodies, a T cell response, and a cellular immune response after just one dose. The response was even stronger on day 71.
A note about the study: The study had its limitations. It is small and the elderly have not been included, so it cannot necessarily be generalized to other age groups. Researchers say they will follow up with these volunteers to see exactly how long this protection can last.
J&J is currently working on several other clinical trials on the Covid-19 vaccine, including to determine if a second dose works better. It is also studying how the vaccine works in children and will study how it works in pregnant women.