Pfizer vaccine may protect against mutant strains of coronavirus ©Danny Lawson/PA News

Pfizer vaccine may protect against new strains of coronavirus

Blood samples taken from patients immunised with the jab contain antibodies which appear to work against a key mutation in the new strains.

The Pfizer/BioNTech COVID-19 vaccine appears to protect against a mutation in two coronavirus variants that are causing rapid spread across the UK, a study carried out at the University of Texas Medical Branch suggests.

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Recently two new strains of the virus have been discovered, one in the UK and one in South Africa, raising concerns about the efficacy of the coronavirus vaccines currently being rolled out.

Both variants contain mutations including one of particular interest called N501Y, an alteration in the spike protein of the virus, which the virus needs to invade cells and is a target for vaccines.

In the new study, which has not yet been peer-reviewed, researchers from the University of Texas Medical Branch and Pfizer carried out lab tests on blood samples taken from 20 people who had received the Pfizer vaccine.

They found that the samples contained antibodies which appeared to provide protection against N501Y in the new strains.

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Pfizer said it has now tested 16 different mutations in the strains and none of them have had any significant impact on how the vaccine works.

However, one of the mutations in the South Africa variant, named E484K, has not yet been studied.

Earlier this week, the UK’s chief scientific adviser Sir Patrick Vallance said it may be that the new strains reduce the efficacy of vaccines but that more studies were needed.

Other UK scientists have given the new findings a cautious welcome but said further research was needed.

“This is good news, mainly because it is not bad news,” said Stephen Evans, professor of pharmacoepidemiology at the London School of Hygiene & Tropical Medicine.

“Had the opposite result been found, that the vaccine did not seem to have efficacy against the variation of the virus studied, that would have been bad and very concerning.

“So, yes this is good news, but it does not yet give us total confidence that the Pfizer (or other) vaccines will definitely give protection.

“We need to test this in clinical experience and the data on this should be available in the UK within the next few weeks.”

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Further studies are now planned on other mutations, Pfizer says.

Can I get the coronavirus twice?

There have been a few stories in the press of people apparently being re-infected by the coronavirus SARS-CoV-2. These people reportedly became infected and hospitalised, and then were sent home once they’d tested negative for the virus. Then, days or weeks later, they tested positive again.

But  according to Dr Jeremy Rossman, lecturer in virology at the University of Kent, this doesn’t necessarily mean that they caught the coronavirus twice.

First, during recovery from infection, a person may have very low amounts of the virus remaining in their body – low enough that our tests can’t accurately detect it. In this case, the person may be sent home on the assumption that they’re virus-free. However, their body may still be fighting the virus, and a resurgence of the virus (and symptoms) can occur, resulting in a positive test. In this case, it would just be one protracted infection, not a re-infection.

Second, we know that in most people, SARS-CoV-2 generates a strong response from the immune system. With the related coronavirus SARS-CoV, this response creates an immune memory of the virus that prevents re-infection for one to two years, and it’s likely that this is also the case for the new virus. SARS-CoV-2 also has a fairly low mutation rate, which means that it (hopefully) won’t change enough that our immune system no longer remembers it (this is what the flu virus does and why we need a new jab every year).

If this all turns out to be true, then it would suggest that re-infections are unlikely and that the cases in the news reflect testing sensitivity. However, SARS-CoV-2 is so new that we won’t know for sure until we’ve found out just how protective our immune response to the virus is, and how long it lasts.

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