Scientists have focused on a handful of mutations in the coronavirus that they say could pose new public health challenges if they circulate widely.
Its focus: the small peak proteins that cover the outside of the virus.
It is these proteins that researchers have successfully targeted to create vaccines, using them to prepare the body’s immune system to make antibodies to fight the virus. But it is also where they observed some mutations that forced vaccine manufacturers to react. A variant found for the first time in South Africa is of particular interest due to mutations in the virus’s spike protein that can make antibodies less effective against it.
And while none of these changes appear to have resulted in a virus capable of escaping current vaccines, it is an area of intense focus for coronavirus researchers.
“The spike protein is like the key that unlocks our cells,” said Simon Clarke, an associate professor of cell microbiology at the University of Reading, UK. “If you have mutations in the peak protein, it can either make the key work more effectively or it can change the structure of the key slightly so that it can still access our cells and now the antibodies cannot bind to it and stop working. “
An earlier analysis by Moderna found that while its vaccine appears to be less effective against the South African variant, the antibodies remained above protection levels. The Pfizer-BioNTech vaccine is only slightly less effective against the South African strain, according to a study that has not yet been peer-reviewed.
The coronavirus has probably gone through thousands of changes since it first spread to humans. Several different variants, including one that was first reported in the UK and another that appears to have appeared in Brazil, are already being tracked around the world.
But scientists remain concerned about the emergence of other variants of the coronavirus, especially if one emerges that makes vaccines obsolete.
“Mutations can make a virus more transmissible or less susceptible to some antibodies, so that’s always a major concern,” said Clarke.
So far, vaccines appear to protect against known variants, said Dr. Bruce Y. Lee, professor of health policy and management at City University of New York. He added that even if a vaccine is less protective against a strain, there will likely still be benefits, such as preventing more serious cases of Covid-19, which not only helps patients, but also minimizes pressure on hospitals and healthcare professionals. .
“It’s like a flu shot is 30% effective, yet we still recommend getting the flu shot,” said Lee.
But that does not mean that there are still no risks – especially with the crucial role played by the virus’s spike protein.
Both the South African and United Kingdom variants contain a spike protein mutation called N501Y, which appears to make these strains more contagious. The South African variant also carries a mutation known as E484K, also in the protein spike, which could make it less susceptible to antibodies produced by vaccines or produced from natural infections.
And since vaccines target the peak protein, Lee said, there is a concern that mutations in this part of the virus may affect how well the vaccines work.
“If you change the peak protein enough, the question will be, how will the immune response change?” he said. “The effectiveness of vaccines really depends on our immune response to that peak protein.”
The research is still ongoing, but the observed declines in vaccine effectiveness have already led Moderna to start adjusting its existing vaccine to make it more effective against emerging strains. Although Moderna’s vaccine appears to be protective against known variants, the company’s CEO, Stéphane Bancel, said last month that the updates are being developed “out of caution.”
AstraZeneca and the University of Oxford, which jointly developed a vaccine authorized for use in the UK but not yet in the United States, announced on Wednesday that they intend to produce an updated version to protect against known variants that may be available on autumn.
And scientists expect more variants to emerge as the pandemic evolves. UK scientists reported on Tuesday that the E484K mutation seen in the South African variant was also found in a small number of cases involving the UK strain in England.
“The more a virus replicates, the more chances you have of random changes,” said Lee. “Many of these changes won’t make a difference, but every now and then, you will get a change that gives the virus an advantage – making it more capable to survive, replicate or infect people ”.
This perspective adds urgency for countries around the world to aggressively control the spread of the virus, thus limiting the opportunity for new, more problematic variants to circulate.
“What we do can really affect the path of the pandemic in the coming weeks,” said Lee.