US biotechnology company Moderna said on Monday that laboratory studies have shown that the Covid-19 vaccine is still effective against types of the Coronavirus first identified in the United Kingdom and South Africa.
But the positive news was tempered by the discovery that there was a six-fold decrease in the level of the equivalent highly potent antibody produced against the South African variant, B.1.351.
Out of caution, the company will test the addition of another booster to the vaccine – To shoot three shots in total – Pre-clinical studies were initiated on a booster specifically for the South African variant.
“We are encouraged by this new data, which strengthens our confidence that the Moderna Covid-19 vaccine should be protective against these newly discovered variants,” said Stephan Bansel, CEO of Moderna.
“Out of extreme caution and leveraging the flexibility of our mRNA platform, we are developing an emerging variant potentiating candidate against the variant that was first identified in the Republic of South Africa in the clinic.”
The emergence of highly contagious variants of SARS-CoV-2 has raised concern about their impact on the effectiveness of Covid-19 vaccines even as countries begin to speed up their immunization programs.
Both variant B.1.1.7 that was first seen in the UK and variant B.1.351 have multiple mutations along the “spiky protein”, which are molecules that spread on the surface of the virus and allow it to invade human cells.
Scientists were particularly concerned that mutations in B.1.351 could cause the virus to escape the action of antibodies and render the current generation of vaccines obsolete.
Moderna vaccine uses mRNA – A type of genetic molecule – To deliver information to human cells to create a spike protein inside the human body, in order to stimulate the immune response.
Hence, the promoter B.1.351 carries the spiky protein-producing RNA with mutations of the variant.
The main advantage of mRNA vaccines is that they can be developed within weeks, although mass production may take much longer.
To study the effect of the Moderna vaccine, called mRNA-1273, the company took blood samples from eight people who had received two doses of the vaccine, and from the primates that had also been vaccinated.
For variable B.1.1.7, there was no effect on the level of neutralizing antibodies – Which binds to the spike protein and prevents it from invading human cells – That was produced by shots.
But for the South African variant, B.1.351, there was a six-fold decrease in the equivalent antibody level.
However, the company said it remained higher than the amount proven preventive in previous tests on primates that were intentionally infected.
Reactions to Moderna’s statement by independent experts have been mixed.
“That’s fine,” Akiko Iwasaki, a leading virologist at Yale University, tweeted, adding that she expected other vaccine makers also to develop boosters that target the South African variant.
Benjamin Newman, a virologist from Texas A&M University, agreed, and told AFP that the decrease in potency related to only one type of antibody, which makes up 1% of the total antibody that binds to the virus protein it uses to enter cells.
“To be clear, 99% of the antibodies that bind to other parts of the spike and do not neutralize it should work well on the mutant strains,” he said.
He added that the decrease in the study “will be more of a cause of upcoming potential problems than a sign of imminent danger,” adding that in a living person, the immune system learns to modify the antibodies it produces if their effectiveness decreases.
But Lawrence Young, a virologist at the University of Warwick in Britain, said that the six-fold reduction was “worrying” and suggested that the effectiveness of the vaccine as well as the duration of protection could be affected.
Moderna, which has conducted studies with the National Institutes of Health, submitted the study to a prepress server so it could be analyzed by the wider scientific community.