The adaptation of COVID-19 vaccines effectively keeps it against new variants

Since the early days of the COVID-19 pandemic, experts have warned that the first batch of vaccines created against the virus may not be the last. Like all viruses, this one would mutate, and eventually the mutations could make the virus different enough that another vaccine would be needed to fight it. Only two months after the vaccination campaign, researchers are preparing for the inevitability.

There is early evidence from South Africa that both the Novavax and the Johnson and Johnson vaccine candidates are not as effective against a variant of the virus first identified in the country, called B.1.351. The shots still provide some defense and still protect against hospitalization and death. Preliminary research indicates that the COVID-19 vaccines already approved in the United States, made by Moderna and Pfizer / BioNTech, will also block this variant.

The first known cases of infection with this strain were reported in the US this week. And although the vaccine appears to be partially effective against the variant, the pharmaceutical company Moderna announced this week that it is starting work on another version of the COVID-19 vaccine. It will be more specifically aimed at B.1.351. This is a good step based on what researchers know so far, says Dylan Morris, who studies viral evolution at the University of California, Los Angeles. “I would say it is wise rather than an emergency,” he says.

Blood drawn from people vaccinated with the Modern COVID-19 vaccine had antibodies that blocked the B.1.351 virus, new research has shown. However, it took about six times more to block this strain than the predominant form of the virus against which the vaccine was designed. Pfizer and BioNTech’s COVID-19 vaccine also produces antibodies that block viruses with mutations found in B.1.351, although it also takes slightly more, preliminary research has shown.

Both of the authorized vaccines initially produce sky-high levels of antibodies, so there is room for a slight decrease in potency. The high starting point means that there are more pillows against changes in the virus, Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said in a press conference last week.

One of the reasons Moderna still wants to update their vaccine is to maintain the impressive levels of antibodies, says Stephen Goldstein, who studies evolutionary virology at the University of Utah. An additional shot designed to target the new variant can theoretically increase the body’s antibody response, even against a formidable enemy. “At least for the next few months we are in good condition with these new variants, but we may want to return to the very high levels of neutralizing antibodies that are the striking feature of these vaccines,” he said. say.

Part of the uncertainty comes because scientists do not yet know what antibody levels someone needs to generate to be protected against COVID-19. “We can not just do an experiment in a laboratory and say it’s time to update the vaccine,” Goldstein says. “There’s a bit of guesswork involved.”

There are a few different ways researchers can extract the guesswork from the comparison. Scientists were able to measure the antibody levels of people who had been vaccinated but still became ill with COVID-19, and identified the cut-off point where the vaccine is not protective. They can also compare the effectiveness of a new vaccine that generates a high antibody response with an older version of the vaccine with a lower potency. Animal models can also work. In December, a team investigated the link between protection and antibody numbers in monkeys and found that relatively low levels block the virus.

Image: Jessica Christian / The San Francisco Chronicle via Getty Images

‘People are measuring it, trying to get a better idea of ​​what the things that are easy for us to measure, such as antibodies, tell us about the thing in which we are most interested, how well can you be protected ? against diseases, ”says Morris.

Scientists already have the information on more well-known viruses, such as flu. Researchers and regulators know what levels of antibodies the flu vaccine needs to generate to provide adequate protection against flu. They do not have to perform a complete clinical trial to test how effective a new flu shot is – instead, the Food and Drug Administration will approve new flu vaccines based on the antibody response they put into a trial. a small group of people. Once a flu vaccine meets the threshold and is approved, the company can adapt it to each new seasonal flu strain without collecting new clinical data. Ideally, researchers could eventually do something similar for COVID-19 vaccines.

It can be a few months before we have a good understanding of the amount of immune response that corresponds to the protection against COVID-19. If they do, the FDA can report updated or booster vaccines based on data showing that a new version could push the body to generate the level of immune response, rather than asking companies to undergo clinical trials.

“The FDA has already considered the development of a possible route if changes need to be made to authorized COVID-19 vaccines or other products based on information on emerging variants,” tweeted Acting FDA Commissioner Janet Woodcock.

The decision to release the enhancements and modified vaccines should also take into account how much of a new form of the virus is circulating in a given area, Goldstein says. At present, there are only two confirmed cases of people in the United States infected with the B.1.351 virus strain, although there may be others that have not been identified. “It’s quite rare outside South Africa, so we do not want to vaccinate people in the US against the tensions that do not occur in the US,” says Goldstein.

Eventually, it can spread more widely, and it can make sense to give people that extra protection. Therefore, it is encouraging that Moderna is now preparing the boosters. “We want to be prepared if the virus is more prevalent,” Goldstein says. Other strains of the coronavirus that are more capable of evading existing vaccines may also emerge in the future. “I think it would be really good to align the technological and regulatory side of things ahead of time, if and when we need to introduce a vaccine update,” Morris said.