Yet another vaccine is now part of our arsenal of weapons against the covid-19 pandemic. On Saturday, the Food and Drug Administration granted an emergency use authorization (EUA) to the one-dose shot developed by Johnson & Johnson. It joins the two-dose mRNA vaccines developed by Moderna and Pfizer/BioNTech.
The regulatory agency made the decision following a meeting and unanimous endorsement Friday by the FDA’s Vaccines and Related Biological Products Advisory Committee, a panel of outside experts that weigh in on potential new approvals. In keeping with the panel’s recommendations, the FDA has authorized the vaccine for people over the age of 18.
According to the clinical trial data used to secure the EUA—studies that involved over 40,000 volunteers in the U.S., South America, and South Africa—J&J’s vaccine is 66% effective at preventing moderate to severe illness from covid-19. Most importantly, it was found to be 85% effective at preventing severe to critical illness after 28 days. No coronavirus-related hospitalizations or deaths were found in vaccinated people after 28 days, though it’s likely the risk of either in vaccinated people isn’t truly zero, just very low. The shot, like the Moderna and Pfizer vaccine, also seems to help prevent some amount of asymptomatic infections, which should reduce the risk of transmission from vaccinated people to others.
Unlike the Moderna and Pfizer/BioNTech vaccines, which are both scheduled as two doses taken a month apart, J&J’s vaccine will be given as a single shot. An ongoing study is testing whether a second dose of J&J’s vaccine taken two months later could boost its effectiveness. The adenovirus-based vaccine is also more stable than either of the other two authorized mRNA vaccines, meaning it doesn’t require ultra-cold temperatures and can be stored in a standard refrigerator without spoiling for up to three months. (Moderna and Pfizer’s vaccines can also be kept in standard refrigeration, but only for a max of two to four weeks.)
All three vaccines were found safe and effective in large trials. But J&J’s vaccine does appear to be better tolerated. In the clinical trial data, 55% of vaccinated people experienced an adverse effect after a shot, with the most common being injection site pain, headache, and fatigue. By contrast, over 80% of people who take a mRNA vaccine are expected to experience at least one symptom after taking the first or second dose. There’s a potential risk of allergic reaction for all three vaccines, but it appears to be very small. Currently, people are asked to wait nearby for 15 minutes after getting a vaccine in case of an allergic reaction.
J&J’s vaccine was being tested just as important variants of the coronavirus began to show up last year, some of which are able to partly evade the immune response created by an earlier infection or vaccination. In South Africa, this vaccine still provided a similar degree of protection to the worrisome B.1351 variant as it did for other strains, though the protection was slightly diminished. Moderna and Pfizer/BioNTech have said that their vaccines should largely work against B.1351, but both have recently launched small clinical trials to test out a booster and/or modified dose strategy against the variant.
J&J has pledged to make nearly 4 million doses of its vaccine available immediately after receiving the EUA. By the end of March, the company has promised to produce 20 million doses. In total, all three companies have stated that they’re on track to produce 240 million doses by the end of March. It’s expected that yet another vaccine—the one developed by Oxford University in the UK and the company AstraZeneca—will reach the American public in April. (On Friday, Canada approved the Oxford/AstraZeneca vaccine.) A fifth vaccine, developed by Novavax, has also reached the end of large-scale testing and is expected to be reviewed for authorization in the U.S. soon.
The pandemic is still going, and there are still far too many people getting sick and dying from covid-19 every day in the U.S. for anyone to be completely at ease. But the release of J&J’s vaccine may very well speed up a return to normal, as more and more people become immune to the virus.