Johnson & Johnson’s COVID-19 vaccine is now the third to receive emergency use authorization from the Food and Drug Administration (FDA). But, unlike the previously authorized vaccines, this one only requires one shot.
The Johnson & Johnson Janssen COVID-19 vaccine is now authorized to prevent coronavirus infections in people 18 and older, according to an FDA press release. Data from clinical trials showed the vaccine can effectively help prevent COVID-19 infections, but it’s not clear for how long that protection lasts or whether or not the vaccine can also prevent transmission of the virus between people, the FDA found. The most common side effects associated with the vaccine include pain at the injection site, fatigue, headache, muscle aches, and nausea, according to data from the clinical trials.
This vaccine works a little differently than the mRNA vaccines that received FDA authorization previously. It uses a type of adenovirus (which has been genetically modified to prevent it from replicating in the human body) to carry part of the coronavirus’s genetic code into the body. With that, the body can create an immune response that will help provide protection from symptomatic coronavirus infections, especially severe ones.
The approval is based on an FDA analysis of results from a phase 3 clinical trial involving about 43,700 participants in eight countries (including nearly 15,000 participants over the age of 60) who were randomly selected to receive either a placebo or the Johnson & Johnson COVID-19 vaccine. There were about 460 symptomatic cases of COVID-19 recorded throughout the study at least 14 days after people were vaccinated. Of those, 348 occurred in the placebo group and 116 occurred in the vaccine group.
Researchers found that, 28 days after vaccination, the vaccine was 85% effective at preventing severe COVID-19 infections and hospitalization, the company says. In fact, the company reported no cases of severe COVID-19 requiring medical intervention among those who received the vaccine after 28 days. The vaccine also appeared to be 66% effective at preventing moderate-to-severe COVID-19 infections (and around 74% when just looking at U.S. data), according to the FDA analysis.
However, the vaccine did lose some efficacy—down to 52% after 14 days and 64% after 28 days—against moderate-to-severe disease in South Africa, according to the FD analysis. That suggests the vaccine may be less effective at protecting people from the B.1.351 coronavirus variant first identified there. (It’s not clear how well this vaccine could protect against the B.1.1.7 variant because, as of mid-February, none of the cases noted in the clinical trials were caused by that variant.)
This vaccine may not be quite as effective as the Pfizer/BioNTech or Moderna mRNA vaccines that were previously authorized, but it’s certainly not ineffective—and it has some advantages over those other vaccines. Perhaps the most significant one is that this vaccine only requires one dose while both of the mRNA vaccines require two doses for maximum efficacy, administered a few weeks apart. With an uncertain vaccine supply and all the other challenges of giving large numbers of people adequate care in the midst of a pandemic, only having to get a single shot is much easier than having to coordinate two.
Ultimately, having more options will definitely be a good thing—especially as vaccine supply and access continues to be an issue in the U.S. And, as experts suggested months ago, we may one day soon be able to choose a vaccine based on a particular person’s risk factors for severe disease as well as their everyday risk for exposure. But, with continued use of face masks, social distancing, and hand washing, these vaccines will undoubtedly help us contain the pandemic—even with the rise of coronavirus variants.