Can the vaccine stop the mutant?This is what we have ever known

It’s official: This week, U.S. health officials said the first strain of coronavirus identified in the UK last winter is now Dominant stock In the United States. And it was found in at least 130 other countries as well.

As a reassuring note, authorities say that all three vaccines approved for use in the United States (Pfizer, Modana, Johnson & Johnson) provide excellent protection against this variant, especially serious illness. Said there was evidence. Similar evidence is beginning to accumulate for additional vaccines being used or considered in other countries.

However, this strain is just one of three “variants of concern” that are widespread in the United States and other countries. One of the other variants that was first identified in South Africa and predominant there is now being found throughout South Africa.The other, first seen by those who traveled from Brazil to Japan, is late. Brazil’s current surge in cases It has also been found in the Americas.

So how well does the vaccine work against these two other variants?

Scientists say answering that question is currently one of the hottest topics in biomedical research.

“We’ve seen an explosion — paper almost every day,” he said. Salim Abdul Karim, An infectious disease researcher co-chairing the COVID-19 Advisory Committee in South Africa.

One of the reasons is that there are so many vaccines to check. Approximately 12 vaccines worldwide are in various stages of approval and use, including the aforementioned vaccines from Pfizer, Modana, Johnson & Johnson and AstraZeneca from Sputnik V in Russia. Indian Covaxin and Chinese Sinovac and Sinopharm.

Abdool Karim said it is important to test as many of these vaccines as possible against the mutants that are currently predominant in his country.

“South Africa’s vaccine strategy requires a diverse range of candidates,” Abdul Karim said. “If something happens, I don’t want to use just one or two vaccines because it’s safe. [problem] Or weakened immunity — I don’t want to know that we are at risk because we only had one vaccine. “

Clinical Evidence: Test It in the Real World

Abdul Karim ideally looks at how vaccines work against South African variants in real-world situations to determine which vaccine makes the most sense for their country. I said I want to know. This is known as clinical evidence.

“And I was very lucky to have some of the vaccines tested in South Africa,” he said.

For example, a large study of Johnson & Johnson vaccines found that it was about 85% effective in preventing serious disease from the predominant variants in South Africa. A small study of the Pfizer vaccine suggests that even mild cases from South African variants can be prevented by as much as 100%.

However, on the less promising side, a Novavax vaccine study found that it was about 89% effective in preventing mild disease from the original strain, but about 50% against the predominant variants in South Africa. It is effective.

“Almost half of the effectiveness is lost,” said Abdul Karim.

To make matters worse, studies of the AstraZeneca vaccine suggest that it may have little ability to prevent mild illness caused by South African variants. It is unclear to what extent AstraZeneca or Novabacs can prevent serious illness.

Lessons from the lab

Next, there are six other vaccines. number Clinical research to go through. To evaluate them, Abdool Karim is considering laboratory studies.

Scientists draw blood from a vaccinated person and extract the antibodies that the vaccine produces against the virus. The antibodies are then placed in a Petri dish containing one of the mutant strains of the virus, or a “pseudovirus” designed to resemble them.

Basically, Abdul Karim said, “They are looking at the amount of antibody needed to kill the virus.”

Some such experiments with the modelna vaccine have shown that the strain is compared to neutralizing the original version of the coronavirus because the antibodies it produces are not effective against South African variants. It suggests that it takes eight times longer to knock out. One study found that more than 40 times more antibodies were needed.

But Abdul Karim said he wasn’t too worried.

For one thing, he concluded that the latter study was likely to be a less confusing outlier. “These are not standardized assays,” he said. The procedure used to perform these experiments and evaluate the results as “labor-to-lab”. Therefore, he tends to believe in the predominance of evidence suggesting that up to eight times more Moderna-producing antibodies are needed against South African strains.

In that case, Abdul Karim said, “The Modana vaccine produces fairly high levels of antibodies, so there are still enough antibodies to neutralize the virus.”

Indeed, it is worth noting that laboratory experiments with Pfizer vaccine antibodies have shown that a similar amount of increase is needed to crush the mutants in South Africa. And, of course, in the case of Pfizer, there is clinical evidence that the vaccine induces enough antibodies to be successful.

In contrast, experiments showed that AstraZeneca required 86 times more antibody to neutralize the South African mutant compared to the original strain. There are no strict rules, but at that point Abdool Karim said, “I don’t know. Basically, I’m not completely confident about the vaccine.”

In fact, he and other officials were very concerned that South Africa had discontinued plans to deploy AstraZeneca in its own country.

Concerns about Brazilian variants

If the first variant discovered in South Africa caused the most astonishment among scientists, the second closest is the variant that is endemic in Brazil.

Kate O’BrienThe director of the World Health Organization’s Department of Vaccination, Vaccination and Biology said the problem of the variant has never been found in studies of vaccine efficacy against it. The results of these findings are actually less alarming. The concern is that these studies are scarce yet.

“There isn’t really enough information to draw substantive conclusions,” O’Brien said.

Still, O’Brien draws hope from what she thinks from “significant” discoveries from mid-February by a team of researchers from Johns Hopkins University and the National Institutes of Health’s National Institute of Allergy and Infectious Diseases.

Instead of focusing on antibodies, these researchers focused on another part of the immune system, including “CD8 + T cells,” which also play an important role in the fight against infectious diseases. The team essentially found that T cells in the blood of people who recovered from the original version of COVID-19 could recognize three mutants of the virus to the same extent.

Due to the involvement of T cells after the infection has progressed, O’Brien suggests that even if certain vaccines are not good at preventing mutant infections, they can at least significantly reduce the severity of the infection. He said he was doing it.

O’Brien said this could affect the usefulness of AstraZeneca and Novabax, especially for South African variants. In both cases, a disappointing clinical study in South Africa only talks about how well these vaccines prevent mild to moderate infections. It is unclear whether either vaccine is very effective in keeping people away from the hospital, as the study did not include older people who were at much higher risk of serious illness.

“We know [that type of protection] “It will be larger than mild, moderate disease,” O’Brien said. “We also know that T cells play a role, especially in severe disease.”

In fact, in the case of AstraZeneca’s study, O’Brien pointed out that the sample size was very small. Even the discovery that the vaccine had little effect in stopping mild illness is marked with an asterisk.

In short, she concludes, “The jury hasn’t come out yet.” “There is a plausible route here where AstraZeneca products may still prevent serious illness, hospitalization and death.”

This all means that authorities are likely to coordinate advice on which vaccine to use where. If that happens, Mr O’Brien said our confidence in policy makers should not be shaken. When they changed their recommendations, she said, “It’s not because policymakers made it wrong in the first place, it’s because of new evidence.”

Copyright 2021 NPR. For more information, please visit https://www.npr.org.