2023-04-16 10:01:08
A Hong Kong study shows that vaccines do not induce the coronavirus to evolve into a variant that escapes those vaccines.
It seems like a logical concern: if you vaccinate everyone against the coronavirus, won’t you create a new variant that is immune to the vaccine in question? After which you have to come up with a new vaccine, and history repeats itself.
Fortunately, that concern seems unfounded. A large study in Hong Kong, published in Nature Communicationsshows that both the Pfizer vaccine and the Chinese Sinovac do not lead to a more dangerous corona variant.
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Well captured
For the study, samples of SARS-CoV-2, as the coronavirus is still officially called, were collected from 2820 different patients. ‘That’s one of the largest numbers to date in this kind of research,’ says Leo Poonprofessor of virology and head of the Department of Public Health Laboratory Sciences at the University of Hong Kong, who led the research.
‘It was well recorded whether a sample came from a vaccinated or an unvaccinated patient’, Poon continues. ‘That allowed us to determine the effect of vaccination on the evolution of the virus.’
Different vaccines
In Hong Kong, the government offered two vaccines during the corona pandemic: the Pfizer vaccine, which was also widely used in the Netherlands, and the Chinese Sinovac-vaccin. These vaccines work in different ways. The Pfizer vaccine is an mRNA vaccine, which the body uses spikeprotein, the protrusion with which the coronavirus gains access to cells. Sinovac is an ‘old-fashioned’ vaccine, which works with a complete, inactivated virus. ‘Previous studies mainly focused on the mRNA vaccines’, says Poon. ‘That makes the Sinovac part of our study unique.’
In addition, more than 90 percent of the genome of the collected viruses was read. ‘A fine study by a good research group’, he concludes Bert Niestersprofessor of medical microbiology and head of the clinical virology section at the University of Groningen, was not himself involved in the work.
Silent mutations
One of the questions that Poon and colleagues focused on was: does vaccinating people lead to new variants that are immune to vaccines? “There are scientists who think that vaccination can accelerate the evolution of the virus, and others who think that this is not the case,” says Poon. “Our findings support the latter view, for both the Pfizer and Sinovac vaccines.”
This does not mean that the coronaviruses did not show mutations in vaccinated patients. But most of the mutations observed were so-called ‘silent’ mutations: mutations that did not make the virus noticeably more dangerous.
Because there are on average per human infection only a few virus particles are passed on from one to the other, most of those silent mutations won’t jump over, says Poon. ‘Mutations that are beneficial to the virus could spread in that way. That is why it is so important that we have established that vaccination does not lead to such ‘non-silent’ mutations in the host.’
First across the line
Poon does not call his findings surprising, by the way. Niesters agrees. “Most selection will not be caused by the vaccinations, but in how efficiently a certain variant of the coronavirus can replicate. And on that point, the omikron variant crossed the line first.’
Niesters also refers to this recent review article, about the evolution of the coronavirus. “The virus will always evolve,” he explains. ‘New variants are constantly emerging and that happens independently of the vaccination. The point is that the induced immunity of the vaccines is of limited duration. We have to adapt the vaccine because the virus is evolving. Not through the vaccination itself, but in a natural and logical, biological way.’
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