South African Variant of SARS-CoV-2 Virus May Evade Vaccines
Story Highlights
- A highly transmissible new strain of SARS-CoV-2, the virus that causes COVID-19, has been identified in South Africa and has now spread to at least eight other countries including the U.K., Switzerland, Finland, Japan, Australia, Zambia, France and South Korea.
- The mutations of the new strain represent significant changes to key structures involved in the virus’s ability to attach to human cells and may impact the effectiveness of vaccines and treatments.
- Lead scientists predict additional mutations of SARS-CoV-2 and manipulation of current vaccines to accommodate the changes.
According to the U.S. Centers for Disease Control and Prevention (CDC), “Multiple SARS-CoV-2 variants are circulating globally,“ with several new variants emerging in the fall of 2020.1 A second new variant of the SARS-CoV-2 virus that can cause COVID-19 has been traced to South Africa and experts are concerned that it may not be fully responsive to the vaccines currently being rolled out, according to Dr. John Bell, a lead professor on the development of AstraZeneca’s experimental COVID-19 vaccine.2 Dr. Bell said the new variant worried him more than another new strain detected recently in the U.K.
Agreeing with Dr. Bell’s statement, U.K. Health Secretary Matt Hancock said, “I’m incredibly worried about the South African variant… This is a very, very significant problem… even more of a problem than the U.K. new variant.”3 Former US. Food and Drug Administration (FDA) commissioner, Scott Gottlieb, MD, noted that the South African SARS-CoV-2 variant appears to interfere with the effectiveness of currently available treatments, saying, “The South Africa variant is very concerning right now because it does appear that it may obviate some of our medical countermeasures, particularly the antibody drugs.”4
New Strain is Highly Transmissible
The new strain was first reported in South Africa in December and spread quickly in three areas, rapidly becoming the dominant variant in Eastern Cape, Western Cape, and KwaZulu-Natal provinces.5 As of Dec. 21, 2020, more than 8,500 COVID-19 patients were hospitalized in South Africa compared to the previous peak of 8,300 reported in August 2020.6 Over the past two weeks, more than 200,000 new cases have been reported in South Africa, with much of the surge blamed on the new strain.7 The variant has now been identified in eight other countries including the U.K., Switzerland, Finland, Japan, Australia, Zambia, France and South Korea.
Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases (NIAID), said he would be surprised if it is not already in the U.S., though it has not yet been detected here.8 Both the U.K. strain (B.1.1.79) and the new South African strain (501.V2) appear to be more easily transmittable than the original strain, though neither is thought to cause more serious or deadly disease.
Virus Mutation is Common But Not Always Significant
Viruses are well known to mutate over time, and most variations are slight and would not be expected to have any impact on how the virus behaves.10 What is concerning scientists about the 501.V2 variant in particular is that some of the mutations identified represent significant changes to the structure of the SARS-CoV-2 virus that may impact its susceptibility to the vaccines.
The South African variant is referred to as “501.V2” because the N501Y mutation is located on the virus’s spike protein. Specifically, the mutations on the spike protein have occurred at the receptor binding domain (RBD), which the virus uses to attach to the human cell and which also is targeted by the vaccines.11 This mutation seems to improve the virus’s ability to attach to the cell and may help explain the increased transmissibility of the new strains. The U.K. variant also has the N501Y mutation but 501.V2 has additional mutations of the spike protein that are not seen in the U.K version.
Dr. Bell explained that one of the ways an immune system reaction protects the body is by interfering with the binding capability of the virus. Referring to the “critical question” of whether the new strains are likely to respond to the vaccines currently in circulation, Dr. Bell said, “My gut feeling is that I think the vaccine will be still effective against the [U.K.] strain. And I don’t know about the South African strain… there’s a big question mark about that.”12
New Mutations May Be Less Susceptible to Vaccines
Acknowledging that the spike protein mutations represent “just one of many mutations in both strains that scientists have worried could make the virus less susceptible to vaccines or treatments,” a group of researchers at Pfizer and the University of Texas Medical Branch conducted a small study, testing the virus on blood samples from 20 people who had been given two doses of the vaccine as part of a clinical trial.13
While that small sample did not show any reduction in neutralization of antibodies among the patients who had received the experimental Pfizer/BioNTech vaccine, the design of the study was flawed according to experts. Deborah Dunn-Walters, chair of the British Society for Immunology’s task force on COVID-19 and immunology, explained that one of the study’s limitations was that the mutations were tested in isolation, whereas they should have been tested together to correct for any potential interactions that could lead to a compound effect.
One of the concerns over emerging mutations is the potential for the virus to evade vaccine-induced immunity “because once a large proportion of the population is vaccinated, there will be immune pressure that could favor and accelerate emergence of such variants by selecting for ‘escape mutants.”14
A number of scientists have pointed out that if a mutation occurs that circumvents current vaccines, it would be pretty easy to “tweak” existing vaccines to accommodate the new variants. According to Dr. Fauci, the flexibility of mRNA vaccines like Pfizer’s and Moderna’s would make it “relatively easy to make the modifications in the vaccine were that necessary,” a process he says would only take a “couple of months.”15
Dr. Bell said, “we’re now in a game of cat and mouse, because these are not the only two variants we’re going to see. We’re going to see lots of variants.”16
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