Many of the people who received a single dose of the Johnson & Johnson Covid-19 vaccine in an initial clinical trial developed neutralizing antibodies to the virus by day eight, and by day 57, all volunteers had, according to one study. published Thursday in the Journal of the American Medical Association.
The U.S. Food and Drug Administration authorized Johnson & Johnson’s single-dose Covid-19 vaccine in February. This is one of the first peer-reviewed studies to show how the single dose of the 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 provisional results of a larger portion of the vaccine trial in the New England Journal of Medicine. This study showed that the vaccine was safe and generated an immune response.
For this part of the initial phase of the trial, Beth Israel Deaconess Medical Center in Boston recruited 25 adult volunteers who were randomized into five different groups. One group got one shot, another got two. In these two groups, the scientists tested two different doses of vaccine. Another group got a placebo.
The scientists checked the antibody levels of the volunteers throughout the trial. For the purposes of this study, they reported total results after 71 days. The company will follow up with 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 on day eight. At day 57, all volunteers who received the vaccine had developed neutralizing antibodies, a T cell response, and a cellular immune response after a single dose. The response was even stronger on the 71st.
A note on the study: The study had its limitations. It is small and does not include the elderly, so it cannot necessarily be generalized to other age groups. Researchers say they will track these volunteers to see exactly how long this protection can last.
J&J is currently working on several other clinical trials on Covid-19 vaccines, including determining whether a second dose works best. She will also study how her vaccine works in children and will study how it works in pregnant women.