There was some geographic variation. The vaccine worked better in the United States – 72% effective against moderate to severe COVID-19 – compared to 57% in South Africa, where it faced a mutated virus that was easier to spread.
Dr Matthew Oughton, an infectious disease specialist at the Montreal Jewish General Hospital, told CBC News that the data from the trial “certainly looks promising for a single dose, which, of course, will ease a lot of the logistics we have handled so far. with current vaccines that have been approved. ”
He said that by examining mixed populations across continents, the J&J trial is not just “looking at the differences in how different groups of people react, it also means that they are capturing different viral variants, so that they have a good idea of the real effectiveness of this vaccine. ”
With vaccinations having got off to a rocky start around the world, experts are counting on a single-dose vaccine that would stretch scarce supplies and avoid the logistical nightmare of getting people to come back for boosters.
However, since some competing vaccines 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 vaccines into the guns quickly.
Matthew Miller, associate professor at the Institute for Infectious Disease Research at McMaster University, told CBC News by email that the decision will depend on several factors, including “lead times for specific vaccines in each country.” and the prevalence of new variants becoming circulating.
“Some high-risk populations may need vaccines that provide higher degrees of protection, while less effective vaccines may be suitable for low-risk populations,” he said.
The Canadian government has signed a deal with Johnson & Johnson for up to 38 million doses of their vaccine, although earlier this month officials said a vaccination schedule had not been finalized.
J&J said within a week it would file for emergency use in the United States and then overseas. It plans to deliver 100 million doses to the United States by June, and hopes to have some ready to ship as soon as authorities give the green light.
The United States Food and Drug Administration has set a threshold of 50% for any COVID-19 vaccine to be considered for emergency use authorization.
The J&J data comes from the preliminary results of a study of 44,000 volunteers that has not yet been completed. Researchers tracked illnesses from 28 days after vaccination – around the time people receiving a two-dose vaccine would have needed another vaccine.
After the 28th day, no vaccinated person had to be hospitalized or died, regardless of whether they were exposed to “regular COVID or those particularly nasty variants,” said Dr Mathai Mammen, head of global research for J & J’s Janssen Pharmaceutical Unit, The Associated Press. When the vaccinees got infected, they got milder illness.
To defeat the scourge that has killed more than two million people around the world, billions will need to be vaccinated, and vaccines currently being deployed in different countries require two doses within weeks of each other for full protection. Early data is mixed on how exactly all of the different types work, but the injections given by Pfizer and Moderna appear to be around 95% protective after the second dose.
But amid the shortages, some countries have advised delaying the second dose of some vaccines with little data on how this would affect protection.