More than 33 million Americans have been completely vaccinated against COVID-19 – more than the number of U.S. cases reported during the pandemic. But the spread of harmful variants, some of which vaccines can partially evade, means we are not out of the woods.
New research indicates that the surveys of Moderna and Pfizer are significantly less effective compared to the variant first found in South Africa, called B.1.351. In the study, blood samples from vaccines were used to compare antibody responses to the original virus and the B.1.351 variant. Those who received the shots had far fewer antibodies that could neutralize B.1.351.
The authors of the study said that both vaccines are also likely to be less effective against P.1, a variant first found in Brazil.
The table below summarizes what we know so far about how well five vaccines work to protect humans against three of the most worrying coronavirus variants.
3 variants, 3 stories
Countless versions of the coronavirus spread worldwide, each separated by a small number of genetic mutations.
Once a bunch of mutations better affect a particular strain to infect humans, more lethal or more able to evade the antibodies generated by a vaccination or a previous infection, geneticists call it a variant of concern.
There are three of these: B.1.1.7, the variant initially spotted in the UK in September; P.1, discovered in December; and B.1.351, which were detected in samples from South Africa dating from October.
A health worker taking a patient’s nasal swab to test for COVID-19 in Cape Town, South Africa.
Nardus Engelbrecht / AP Photos
They share a mutation that affects the shape of the virus’ ear protein, which it uses to invade cells. This is perhaps the reason why these variants are more transferable.
Studies have found that the B.1.1.7 variant – reported in 94 countries, including the US – is 50 to 70% more contagious than its predecessors. Recent evidence suggests that people infected with this variant may have a higher risk of death than those who get other strains.
The B.1.351 variant has been reported in 48 countries and 23 US states. But studies have not found it to be more deadly than the original virus.
The same is true for the P.1 variant, which according to a study from March was 40% to 120% more transmissible than earlier versions of the virus. P.1 has been detected in 26 countries and ten U.S. states.
A nurse showing a COVID-19 vaccine manufactured by Chinese company Sinovac.
SILVIO AVILA / AFP via Getty Images
Research suggests that existing vaccines work to protect humans against B.1.1.7, but that they are less effective against B.1.351 and P.1. This is probably because the two variants have a mutation that can prevent the antibodies generated as a result of the original virus from recognizing it.
This genetic modification is mostly missing in the B.1.1.7 variant, although British researchers did find 11 cases of B.1.1.7 with the mutation in a set of more than 200,000 samples.
B.1.351 and P.1 also have a mutation that can help bind the virus more strongly to cells.
What these variants mean to you
Both Pfizer and Moderna said in January that they plan to develop and test booster shots to tackle the B.1.351 variant. This means that vaccinated people may need to get a follow-up shot. Until then, people who have been vaccinated or previously had COVID-19 may still be at risk of becoming infected by the B.1.351 and P.1 variants.
A nurse received a COVID-19 vaccine on December 15 in Galveston, Texas.
Mark Felix / AFP via Getty Images
However, vaccines probably still provide some protection against these variants, even if they are less effective.
“The more vaccines we can get in the arms of humans, the fewer overall infections,” said Kristian Andersen, an immunologist at the Scripps Research Institute in California. tweeted in January. This includes infections with the B.1.351 and P.1 variants, he added.
What’s more, the variant jumps in the same way as the original virus between hosts, so social spread and the use of personal protective equipment should still help stop its spread. Therefore, the mitigation measures remain critical – especially if you are exposed to a more transmissible variant, you are more likely to become infected.
“Let’s get our genomic monitoring in place, better masks, more masks, much more wide testing and selection – and avoid gatherings and busy environments,” Andersen wrote. “Combine that with accelerated vaccine distribution and an accelerated plan for updated enhancers.”
Dr. Catherine Schuster-Bruce contributed reporting to this story.