A third effective weapon was added to the American arsenal against the coronavirus on Saturday when the Food and Drug Administration granted emergency approval for a vaccine developed by Johnson & Johnson.
The company announced it would begin shipping millions of cans earlier this week and ship 100 million cans to the US by the end of June. Together with 600 million doses of the country’s first two approved vaccines, manufactured by Pfizer-BioNTech and Moderna, due to be dispensed over the next four months, that should be enough to cover every American adult who wants to be vaccinated.
The new vaccine is very different from the two already used in the US. Here’s how they compare.
One shot instead of two
The Johnson & Johnson vaccine is given in one shot, while the Pfizer BioNTech and Moderna vaccines are given in two shots several weeks apart.
Thats how it works
The Johnson & Johnson vaccine uses a different method to prepare the body to fight Covid-19: a viral vector called Ad26. Viral vectors are common viruses that have been genetically modified so that they do not cause disease, but can still cause the immune system to build up its defenses. The vaccines Pfizer-BioNTech and Moderna use messenger RNA for this.
How well it works
The Johnson & Johnson vaccine is found to be highly effective in preventing serious illness and death, as are Pfizer-BioNTech and Moderna vaccines. It’s also very effective in preventing milder diseases, albeit a little less than either of these. It appears to be good against the highly contagious variant B.1.351, which was first identified in South Africa and has caused problems at least one other vaccine candidate.
Storage and handling
The Johnson & Johnson vaccine does not need to be stored at extremely low temperatures like the Pfizer BioNTech vaccine. It can be safely stored in a regular refrigerator for three months, much longer than the Moderna vaccine, which spoils after a month if left frozen.
Side effects
The Johnson & Johnson vaccine appears to be less susceptible than the Pfizer-BioNTech and Moderna vaccines to causing the types of side effects that need to be monitored after injection, which may make it more suitable for drive-through vaccination site use. It has been reported that side effects tend to be more felt after second doses that the Johnson & Johnson vaccine doesn’t need.
