J&J said on Friday that in the US and seven other countries, the single vaccine was overall 66% effective in preventing moderate to severe disease, and much more protective – 85% – against the most severe symptoms.
There was some geographic variation. The vaccine worked better in the US – 72% effective against moderate to severe COVID-19 – compared to 57% in South Africa, where it dealt with an easier-to-spread mutated virus.
“Gambling on one dose was well worth it,” said Dr. Mathai Mammen, global research director for J & J’s Janssen Pharmaceutical division, at The Associated Press.
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With vaccinations off to a rocky start worldwide, experts had counted on a single-dose vaccine that would stretch scarce supplies and prevent the logistical nightmare of people returning for boosters.
But with some other competing vaccines that have been shown to be 95% effective after two doses, the question is whether a little less protection is an acceptable trade-off for getting more guns in the arms quickly.
The company said it will file for emergency use in the US and then abroad within a week. It expects to deliver 100 million doses to the US by June, and expects to have several ready for shipment as soon as the authorities give the green light.
These are preliminary findings from a survey of 44,000 volunteers that has not yet been completed. Researchers tracked illnesses from 28 days after vaccination – about the time when participants received a two-dose variant instead, they would have needed one more injection.
After Day 28, no one who was vaccinated needed to be hospitalized or died, regardless of whether they were exposed to “regular COVID or these particularly nasty variants,” Mammen said. When the vaccinees became infected, they had a milder disease.
To overcome the plague that has killed more than 2 million people worldwide, billions must be vaccinated, and the shots rolled out in various countries so far all require two doses a few weeks apart for full protection. Initial data is mixed on exactly how well all different strains work, but shots taken by Pfizer and Moderna appear to be about 95% protective after the second dose.
But amid shortages, some countries have advised delaying the second dose of certain vaccines with little data on how that would affect protection.
All COVID-19 vaccines train the body to recognize the new coronavirus, usually by spotting the spikey protein that envelops it. But they are made in very different ways.
J & J’s shot uses a cold virus like a Trojan to deliver the spike gene into the body, where cells make harmless copies of the protein to boost the immune system in case the real virus comes along.
Rival AstraZeneca makes a similar cold vaccine, which requires two doses. Both the AstraZeneca and J&J vaccines can be kept in the refrigerator, making them easier to ship and use in developing countries than the frozen kind from Pfizer and Moderna.
It is not clear exactly how well the AstraZeneca version, which is used in Great Britain and several other countries, works. Tests in Britain, South Africa, and Brazil suggested two doses are about 70% effective, although there are questions about how much protection older adults receive. An ongoing US study may provide more information.
J&J said the vaccine works consistently in a wide variety of people: one-third of the participants were over 60 and more than 40% had other diseases that put them at risk for severe COVID-19, including obesity, diabetes and HIV.
J&J said the vaccine is safe, with responses similar to other COVID-19 shots, such as a fever that occurs when the immune system is activated.
While it has released few details, the company said there were no serious allergic reactions. But occasionally other COVID-19 vaccines cause such reactions, which can be reversed if treated immediately – and authorities have warned people to be wary no matter what type of vaccine is used.
J&J had covered its bets with a study of a two-dose version of its vaccine, which is still ongoing.
Friday’s interim results come on the heels of another vaccine in the latest test. Novavax reported this week that its vaccine has been shown to be 89% effective in a UK study and that it also appears to work – although not as well – against new mutated versions of the virus circulating in Britain and South Africa. A larger study in the US and Mexico is still enrolling volunteers.
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The Associated Press Department of Health and Science is supported by the Science Education Department of the Howard Hughes Medical Institute. The AP is solely responsible for all content.
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