BOSTON: Antibodies produced by some Covid-19 vaccines are less effective in neutralizing new circulating variants of the new coronavirus, such as those reported for the first time in the United Kingdom, South Africa and Brazil, according to a new study.
The research, published in the journal Cell, found that neutralizing antibodies induced by the Pfizer and Moderna Covid-19 vaccines were less effective against the coronavirus variants first described in Brazil and South Africa.
According to scientists, including Alejandro Balazs, from Massachusetts General Hospital (MGH), in the United States, neutralizing antibodies act by binding strongly to the virus and blocking its entry into cells, preventing infection.
They said this connection only happens when the forms of the antibody and the virus combine perfectly with each other “like a key in a lock”.
If the shape of the virus changes where the antibody binds to it – in this case, the peak protein of the new coronavirus – they said the antibody may no longer be able to recognize and neutralize the virus as well.
In the study, the researchers developed assays for Covid-19, comparing how well the antibodies worked against the original strain and against the new variants.
“When we tested these new strains against vaccine-induced neutralizing antibodies, we found that the three new strains described for the first time in South Africa were 20-40 times more resistant to neutralization,” said Balazs, who is also an assistant professor of medicine at Harvard. US School of Medicine.
According to the scientists, the two strains initially described in Brazil and Japan were five to seven times more resistant, compared to the original strain of the Wuhan SARS-CoV-2 virus in China.
“In particular, we found that mutations in a specific part of the spike protein called the receptor-binding domain were more likely to help the virus resist neutralizing antibodies,” said Wilfredo Garcia-Beltran, first author of the MGH study.
The study noted that the three South African variants, which were the most resistant, shared three mutations in the receptor-binding domain, which may contribute to their high resistance to neutralizing antibodies.
However, the scientists said that the ability of these variants to resist neutralizing antibodies does not mean that the vaccines will not be effective.
“The body has other methods of immunological protection besides antibodies. Our findings do not necessarily mean that vaccines do not prevent Covid, just that the antibody portion of the immune response may have trouble recognizing some of these new variants,” said Balazs.
The researchers added that understanding which mutations are most likely to allow the virus to evade vaccine-derived immunity is essential to developing next-generation vaccines that can provide protection against new variants.
They said it could also help researchers develop more effective preventive methods, such as broad-protection vaccines that work against a wide variety of variants, regardless of which mutations develop.
The research, published in the journal Cell, found that neutralizing antibodies induced by the Pfizer and Moderna Covid-19 vaccines were less effective against the coronavirus variants first described in Brazil and South Africa.
According to scientists, including Alejandro Balazs, from Massachusetts General Hospital (MGH), in the United States, neutralizing antibodies act by binding strongly to the virus and blocking its entry into cells, preventing infection.
They said this connection only happens when the forms of the antibody and the virus combine perfectly with each other “like a key in a lock”.
If the shape of the virus changes where the antibody binds to it – in this case, the peak protein of the new coronavirus – they said the antibody may no longer be able to recognize and neutralize the virus as well.
In the study, the researchers developed assays for Covid-19, comparing how well the antibodies worked against the original strain and against the new variants.
“When we tested these new strains against vaccine-induced neutralizing antibodies, we found that the three new strains described for the first time in South Africa were 20-40 times more resistant to neutralization,” said Balazs, who is also an assistant professor of medicine at Harvard. US School of Medicine.
According to the scientists, the two strains initially described in Brazil and Japan were five to seven times more resistant, compared to the original strain of the Wuhan SARS-CoV-2 virus in China.
“In particular, we found that mutations in a specific part of the spike protein called the receptor-binding domain were more likely to help the virus resist neutralizing antibodies,” said Wilfredo Garcia-Beltran, first author of the MGH study.
The study noted that the three South African variants, which were the most resistant, shared three mutations in the receptor-binding domain, which may contribute to their high resistance to neutralizing antibodies.
However, the scientists said that the ability of these variants to resist neutralizing antibodies does not mean that the vaccines will not be effective.
“The body has other methods of immunological protection besides antibodies. Our findings do not necessarily mean that vaccines do not prevent Covid, just that the antibody portion of the immune response may have trouble recognizing some of these new variants,” said Balazs.
The researchers added that understanding which mutations are most likely to allow the virus to evade vaccine-derived immunity is essential to developing next-generation vaccines that can provide protection against new variants.
They said it could also help researchers develop more effective preventive methods, such as broad-protection vaccines that work against a wide variety of variants, regardless of which mutations develop.