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No one wants a needle to get stuck twice, so naturally many think COVID-19, which provides protection against disease after a single injection, is a good thing.
Two new studies published today suggest that this may be possible.
Both studies involved rhesus macaque monkeys. In one study, researchers at the Beth Israel Deacon Medical Center and the pharmaceutical company Janssen injected either a vaccine candidate or an inert placebo. Six weeks after vaccination, the researchers infected the animals with coronavirus, both in the nose and in the throat.
All 20 animals who received an inert placebo injection showed signs of lung and nasal infection after exposure to the virus. But one of the vaccine candidates seemed quite effective in preventing infection. Of the six animals vaccinated with this particular candidate, none had signs of infection in the lungs and only one showed signs of infection in the nose.
It is the parent company of the Janssen candidate, Johnson & Johnson has decided to start testing people. Initial trials began this week.
The vaccine is a so-called viral vector vaccine. It uses a harmless virus to transmit genetic material from the coronavirus to the person being vaccinated. This is the approach the company has been taking for many years.
“We have now vaccinated 80,000 people against various vectors,” said Paul Stoffels, chief science officer at Johnson & Johnson. And of course it’s safe.
In another study, researchers at the National Institute of Allergy and Infectious Diseases tested another viral vector vaccine, developed by Oxford University. Some animals are vaccinated once, others twice. As in another study, the investigator infected the monkeys with the virus and waited for what would happen.
None of the vaccinated monkeys developed the disease, but all of them still showed signs of active upper respiratory tract infection.
From July 1. Approximately 8,000 volunteers participated in the study on the Oxford vaccine. If it is proven to prevent human disease, that would certainly be a good thing. But if this does not prevent an upper respiratory infection, it means that the vaccinated person can still spread the disease.
A third study published earlier this week, which also involved macaques, suggested the vaccine being developed at the National Institutes of Health, and the biotechnology company Moderna is also proving that it can prevent COVID-19.
“I think it’s gratifying,” said Carlos del Rio, a professor of medicine and epidemiology at Emory University School of Medicine. “But at the end of the day, it’s just animal models.”
He says that only when tests are performed on humans will we really know how effective the tested vaccines will be.