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Scientists at the Food and Drug Administration said Wednesday that the single-shot Covid-19 vaccine developed by Johnson & Johnson is effective and prevents hospitalizations from the disease.

Johnson & Johnson also revealed new, encouraging data showing the vaccine may do a better-than-expected job at protecting patients against new variants of the virus that causes disease. At the same time, FDA experts said the company’s study, results of which were originally made public in a Jan. 29 press release, includes insufficient information to draw conclusions on efficacy in people older than 75.


Documents from the FDA scientists, as well as separate documents from Johnson & Johnson, were released ahead of a Friday meeting of an FDA advisory panel in which outside experts will discuss and then vote on the risks and benefits of the new vaccine. The panel, known as the Vaccines and Related Biological Products Advisory Committee, makes recommendations to the FDA; the agency is not required to follow them, but it generally does.

The J&J vaccine is the first vaccine to show efficacy given as a single dose. It also does not need to be kept frozen when being shipped, as the vaccines developed by Moderna and the team of Pfizer and BioNTech do. Both of those advantages could be profound when it comes to vaccinating as many people as possible, a key step in slowing the spread of SARS-CoV-2.

Overall in the study, the vaccine reduced cases of Covid-19 that were rated as moderate to severe by 66.1% when considering cases occurring at least 28 days after vaccination. There were 193 cases that occurred at least 28 days after vaccination in the placebo group and 66 in the vaccine group. As of Feb. 5, there were seven Covid-19 related deaths in the placebo group and none in the vaccine group.


FDA researchers conducted a new analysis of how frequently volunteers in the study were hospitalized for Covid. When researchers counted cases 28 days after vaccination, there were zero hospitalizations in the vaccine arm and 16 in the placebo arm. For the full analysis set starting with the first dose, there were six hospitalizations for those who received the vaccine and 42 for those who did not.

Johnson & Johnson and the National Institutes of Health initially announced interim results of a 44,325 study testing the vaccine’s efficacy on Jan. 29. At the time, they said the 66% efficacy varied by geography. The vaccine was 72% protective in the U.S., compared to 58% in South Africa, where a new variant of SARS-CoV-2 is circulating.

In new documents, Johnson & Johnson said that in South Africa, the vaccine reduced severe or critical Covid-19 by 81.7% starting 28 days after vaccination, but that efficacy against more moderate disease was 64%. But the company said that the vaccine efficacy was not affected by the high prevalence of another variant in Brazil.

Unexpected side effects occurred at the same rate overall among volunteers who received vaccine and placebo — about 0.5%. However, some rare conditions appeared more common with the vaccine. Blood clot-related conditions occurred in 15 volunteers who received the vaccine and 10 who received placebo. Tinnitus, a ringing in the ears, occurred in six volunteers who received the vaccine and none who received placebo. The FDA said it will recommend monitoring for thromboembolic events after an EUA is granted.

Expected side effects that are related to the vaccine’s effect were common. Nearly half of volunteers reported injection site pain, 38.9% reported headache, 38.2% fatigue, and 33% reported muscle aches.

Johnson & Johnson also conducted an analysis in 2,650 volunteers looking at whether those who received the vaccine were less likely to test positive for the SARS-CoV-2 virus, which causes Covid-19, without having symptoms. There were 50 such cases in the placebo group compared to 18 among those who received the vaccine, a 65.5% reduction.

The United States has purchased 100 million doses of the vaccine, with an option to buy another 200 million doses. The agreement, announced last August, netted J&J over $1 billion in a contract with the Biomedical Advanced Research and Development Authority and the Department of Defense.

That said, the company currently has a limited number of doses to contribute to the effort to step up the country’s vaccine rollout. It will be April before J&J begins to have substantial amounts of vaccine to feed into the distribution pipeline, Moncef Slaoui, former co-chair of Operation Warp Speed, said earlier this year.

However, the company and the NIH said the vaccine was 85% effective at preventing severe disease, with no differences seen across the eight countries included in the study.

J&J is also conducting a trial in the United States of a two-dose vaccine, with the doses given eight weeks apart.The results from that 30,000 person trial are not expected until sometime in May.

The FDA documents represent the first close look at the data released Jan. 29, and are the result of a three-week effort by FDA scientists to independently evaluate the data generated in the trial. Friday’s panel will provide a deeper look at what those data actually mean.

  • I’ve heard of a new Covid DNA vaccine under trial by Inovio Pharmaceuticals. Has anyone Heard about this vaccine, how Clinical trials and production of the vaccine are going and when this vaccine will be available? I’ve heard it is 100% effective with minimal side effects!

  • Hi, Late last year I volunteered for the Ensemble Clinical Trail as a participant in the Pittsburgh region. They were looking for folks in their mid sixties with some comorbidities and figured it was something I could do to help researchers ascertain the efficacy and safety of the one shot vaccine. I’m not medically trained but have lots of experience as a patient having survived a serious trauma in 98. I believe this study has been well conducted and is all data driven by the science. All the doctors and staff were extremely professional. I don’t know if I’ve received the vaccine candidate or the placebo as it’s a double blind study. I’m looking forward to hearing this vaccine gets approved for emergency use authorization and hopeful that more people will get the vaccine in the coming weeks.

  • Thank you for this important review. I would appreciate it if someone can explain the calculation of a 66.1% reduction in the fifth paragraph and the calculation of a 65.5% reduction six paragraphs from the end of the article.

  • Now the question is when the same can be expected for Novavax?

    Other countries may start receiving Novavax doses before the US, even though Novavax is based in Maryland. Novavax has been reaching out and looking for and making deals with production partners, and not being overly protective of its “intellectual property” like the larger corporations. Meaning more doses can reach more people sooner.

    • AstraZeneca beats all global production efforts so far: it licensed manufacturing to 10 countries : UK, Spain, India, Japan, South Korea, China, Australia, Argentina, Brazil and Mexico …..

    • Well AstraZeneca is a western European corporation. So they already had European(EU) based suppliers and manufacturing sites.

      Initial vaccine doses of the AstraZeneca vaccine(AZD1222) came from the Oxford Vaccine Group in the UK, I know at least 1 series production plant I believe in or near Wales is supplying the UK and Ireland. The EU is being supplied by facilities in Belgium and Italy, potentially also from Sweden. Don’t know about Spain(though possible).

      I know they announced their intention to partner with SK Bioscience in South Korea Emergent BioSolutions in the US, but so did Novavax. Emergent Biosolutions is also supplying J&J.

      AstraZeneca’s primary manufacturing partner in Asia is the Serum Institute of India(SII), the “green label”(Covishield) vaccines in Asia and Africa are coming from here. South Africa received its doses from here(which it then rejected). SII has also made production deals with other companies, also including Novavax for more than 1 Billion doses. It remains to be seen if they can deliver on this.

      China so far is just producing its own local vaccines(made and developed by Sinovac, Sinopharm, and CanSino-Bio). Certain small manufacturers in China announced plans to produce Pfizer’s vaccine and the Russian GamCovidVac(Sputnik-V) vaccine, but so far this was not started. Similar announcements may have been made about AZD1222.

      There was talk about producing AZD1222 in Australia, but I believe they are getting Covishield from India right now(they also have a deal with Novavax). Argentina and Brazil (from what I have read) are receiving doses from the UK and EU. I have not seen anyone mention producing any vaccines in Mexico.

      AstraZeneca’s vaccine is not a simple inactivated or attenuated vaccine(like the vaccine from China’s Sinovac or Russia’s new CoviVac vaccine), not everyone is going to be able to replicate its production process.

  • I have read that the J&J vaccine reduced serious Covid disease by 85% and that there were no hospitalizations in any of those vaccinated. What happened to the 15% who did develop serious disease. It would seem that those people would have required hospitalization?

    • My understanding is that 85% efficacy against severe COVID doesn’t mean that 15% of the vaccine group got serious symptoms. As I understand it, it actually means that 85% of all trial participants (counting both the control group & vaccine group) who got serious COVID were in the control group.

    • Good pickup on this apparent contradiction. 85% figure comes from all cases – any time. The No hospitalization figure starts at day 29 and onward so hospitalization in first 28 days were not included here. That is fair as Moderna 95% figure started at day 29 also( day after 2nd dose)

    • Efficacy formula for vaccine is
      1-(vaccine cases divided by control cases) times 100%. Another way to think about is by what percent did vaccine reduce cases compared to control group.

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