- South Africa’s public health agency confirmed that the B.1.351 (501.V2) coronavirus mutation that was detected in mid-December could evade the action of neutralizing antibodies developed after COVID-19.
- According to the agency, half of the blood samples tested against the strain showed that all neutralizing activity was lost. In the other half, the levels of antibodies were reduced, so the risk of reinfection could not be determined.
- The National Institute for Communicable Diseases advises people who had COVID-19 to continue adhering to public health measures to limit the risk of reinfection.
The novel coronavirus has been infecting humans for more than a year old, but it’s still too new for researchers to know everything about it. There’s a massive scientific effort underway to understand the new threat, and we’ve witnessed plenty of breakthroughs so far. Scientists figured out early in the pandemic how to make effective and safe vaccines and delivered finalized products by the end of 2020. Other teams studied transmission and measures to prevent it. Doctors also tested numerous treatments, devising several protocols based on drugs that are effective against the pathogen. All these discoveries helped doctors and public health experts save more lives.
There is one major question that doesn’t have a definitive answer. We have no idea how long COVID-19 immunity lasts, which is a key detail for managing the pandemic. We saw an increasing number of studies in the past few months that showed coronavirus immunity might last longer than expected. Researchers have shown that neutralizing antibodies can patrol the blood for as long as 6 months after the infection, while COVID-specific B and T cells live for at least 8 months. This is all good news for vaccines, which will induce an even more powerful immune response than the virus. But researchers will also share bad news when such data presents itself, and that’s what happened earlier this week. South African health experts confirmed that the coronavirus mutation announced in mid-December could evade neutralizing antibodies that COVID-19 survivors develop.
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Antibodies are proteins the immune system creates in response to pathogens. The ones that can block the foreign agent from infecting cells are called neutralizing antibodies. They kill the coronavirus in COVID-19, preventing it from multiplying. Vaccines also induce neutralizing antibodies, with the immune system producing increased quantities after immunization.
The B.1.351 mutation that’s more infectious than its progenitors features several genetic changes, including modifications that impact the spike protein. Pfizer and BioNTech conducted an early in-vitro experiment that showed vaccine antibodies are effective against one of the mutations that appear both in B.1.351 and in the UK mutation.
South African researchers conducted a similar experiment using neutralizing antibodies from COVID-19 survivors. They took blood samples from 44 people who had COVID-19 and then exposed the B.1.351 strain to the blood. The conclusions indicate that the risk of reinfection with B.1.351 is more than theoretical.
“The blood samples from half the people we tested showed that all neutralizing activity was lost,” the National Institute for Communicable Diseases (NICD) wrote in an FAQ. “This suggests that they may no longer be protected from re-infection.” The South African public health agency noted that in the other half, “the levels of antibodies were reduced and so the risk of re-infection is not known.”
“It is therefore important that people who have previously had COVID-19 continue to adhere to public health measures,” NICD wrote. “Protecting ourselves through masks, regular washing or sanitizing of hands, cleaning of surfaces, and social distancing remain the best defense against all SARS-CoV-2 viruses, including the new lineage.”
Whether it’s Pfizer/BioNTech or NICD’s, the neutralizing antibodies experiments do not tell the full COVID-19 immunity story. These are lab tests that only factor in neutralizing antibodies. The immune response that follows an infection like COVID-19 is more complex, as it involves those highly sophisticated white blood cells that also participate in the defense against the virus. B cells will remember the pathogen and produce new antibodies, while T cells will kill infected cells. The immune response will also react to new strains and create additional antibodies that could neutralize the mutation. Vaccine makers like BioNTech already confirmed that their drugs could be modified in response to mutations. That’s what happens with the flu vaccines, which need yearly updates. The coronavirus doesn’t mutate as much as the flu, however.
There’s also disease severity to take into account. Cases of COVID-19 reinfection have been documented before these infectious coronavirus strains were discovered. Those cases were limited, however. Many speculate that reinfections should be mild for most people who have already defeated the virus. The goal of vaccines is also to reduce the risk of severe COVID-19.
While B.1.351 might be dominant in South Korea, the strain was already observed in other countries. Whether it can evade natural immunity or vaccines or not, the mutation can spread more efficiently. That’s why people should continue to respect health measures, even if they were vaccinated or survived infection.
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