DJ The New Covid-19 Strain in South Africa: What We Know -- 4th Update
A more contagious strain of the coronavirus, first discovered in South Africa, has now been detected in the U.S. The variant has raised concerns over how it will respond to Covid-19 vaccines and whether people who already had the disease could get it again from the new strain.
What is the new coronavirus variant that was first discovered in South Africa?
It is normal for viruses to mutate, and most mutations observed so far in the coronavirus sweeping the globe have made little difference to how it functions. The South African variant, known as B. 1.351 or 501.V2, has worried scientists because of its unusually large number of mutations, especially in the spike protein, which the virus uses to attach to and infect human cells. The spike protein is also the part of the virus targeted by Covid-19 vaccines and antibody treatments.
How dangerous is this new strain?
The discovery and spread of the variant in South Africa coincided with a powerful surge in infections in the country. South African researchers say they believe that the new variant is around 50% more contagious, based on the much faster rate of Covid-19 transmission since its emergence and biological studies of changes to the structure of the virus, which appear to make it easier for it to attach to and infect human cells. The new strain quickly crowded out other versions of the virus circulating in the country. Still, they say human behavior also contributed to the rise in infections. The researchers say that the new variant doesn't appear to lead to more severe cases of Covid-19.
Are there any cases of this new strain in the U.S.?
Health authorities in South Carolina and Maryland have identified people who were infected with the South African variant. At least some of those people haven't traveled abroad recently, suggesting that the variant is potentially circulating in the community. The variant has also been detected in people with no recent travel history in the Canada, Israel, and several countries in Europe and Africa.
How is the new coronavirus strain different from the one discovered in the U.K.?
The scientists who sequenced the South African variant's genome say it has a mutation -- known as N501 -- that it shares with a separate variant discovered in the U.K. Scientists say that mutation is likely responsible for making the variants more transmissible.
But the South African variant also has several other important mutations that have changed the shape of the virus's spike protein, through which the virus attaches to and infects human cells. Laboratory studies using viruses grown in vitro have found that some of these mutations, including one known as E484K, have made the variant more resistant to antibodies triggered by a previous Covid-19 infection or certain Covid-19 vaccines.
Earlier in February, U.K. health authorities said they have found some samples of the U.K. strain that appeared to have independently acquired the E484K mutation. Yet another variant, first discovered in Brazil, also has that mutation.
Will existing vaccines work against the South African variant?
Results from human clinical trials and laboratory tests released so far suggest that current Covid-19 vaccines will still work against the new strain, although not as effectively as against other versions of the virus.
Novavax Inc. and Johnson & Johnson, whose vaccines have yet to be authorized, found that their shots were less effective in clinical trials in South Africa than in other countries where the new variant isn't yet dominant, including the U.S. and the U.K. Novavax's shot protected 60% of HIV-negative recipients in South Africa against developing Covid-19 symptoms -- compared with 89% in the U.K. J&J's shot, meanwhile, was found to be 57% effective against moderate and severe Covid-19 in South Africa, compared with 72% in the company's U.S. trial.
Both trials were conducted when the new strain was by far the most common in South Africa and the efficacy rates were still above the 50% health regulators have set as a threshold for Covid-19 vaccines.
Scientists at Moderna Inc. and Pfizer Inc. -- whose shots have been approved in the U.S. -- have said that their vaccines appeared to be somewhat less powerful against the new strain in preliminary laboratory experiments, but that they still expect them to work. Laboratory studies such as the ones conducted by Pfizer, Moderna and the scientists in South Africa are among the first tests researchers run when they want to understand more about a new virus strain.
Concerns around vaccine efficacy emerged after two other lab studies in South Africa found that the new variant was either entirely or partly resistant to antibodies in blood drawn from people who had previously recovered from Covid-19.
Moderna, Novavax, J&J as well as Pfizer and its partner BioNTech SA have said they are developing modified versions of their vaccines to target either the South African variant or future strains that may make the current shots less effective.
Results from a South African clinical trial of the Covid-19 vaccines developed by the University of Oxford and AstraZeneca PLC are expected soon.
Does the new variant mean that people who have already had Covid-19 could get it again?
The South African trial of Novavax's Covid-19 vaccine also produced a potentially worrying finding on reinfections: Among the participants who didn't receive the shot, an earlier Covid-19 infection didn't appear to protect them against catching the disease again from the new strain circulating in the country.
The trial is the first major analysis of how the South African variant functions differently in humans compared with earlier versions of the virus. Its findings are in line with earlier lab studies that also showed that mutations in the new strain made it more resistant to antibodies triggered by a previous Covid-19 infection.
If confirmed by other vaccine trials currently under way in South Africa, the finding that people who have already had Covid-19 can get infected again by a new variant could have important repercussions for the world's fight against the coronavirus pandemic. It suggests that reaching herd immunity through natural infection may be difficult if the virus mutates in ways that allow it to evade the human immune response.
Do existing Covid-19 treatments work against the South African variant?
Because the variant doesn't appear to cause more severe cases of Covid-19, best-practice medical treatments for hospitalized patients, such as giving them oxygen or putting the most severely ill on a ventilator, don't have to change. However, the South African variant appears to be resistant to a monoclonal antibody drug made by Eli Lilly & Co., the first to be authorized in the U.S. by the Food and Drug Administration, making it less effective in patients infected by that variant, according to the company. The second drug cleared by the FDA, from Regeneron Pharmaceuticals Inc., should still be effective, because it is a cocktail of two distinct antibodies and only one of them is affected by the South African variant, said Jesse Bloom, a biologist and associate professor at Fred Hutchinson Cancer Research Center.
What measures are being put in place to handle the new variant?
The U.S. and many other countries have banned travel from South Africa for noncitizens and imposed stricter quarantine requirements for people coming from the country. Many governments are also trying to speed up their vaccination campaigns in an effort to stop new variants from becoming dominant.
Several vaccine makers are working on updating their Covid-19 shots to make them more effective against the South African strain, while the U.S Food and Drug Administration is taking steps such as requiring smaller trials in order to accelerate the review and authorization of modified vaccines.
--Peter Loftus contributed to this article.
Write to Gabriele Steinhauser at email@example.com
(END) Dow Jones Newswires
February 05, 2021 09:09 ET (14:09 GMT)
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