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The continued spread of the SARS-CoV-2 virus has spawned a Greek alphabet of variants – a naming system used by the World Health Organization (WHO) to track new mutations in the virus that causes Covid-19. Some have equipped the virus with better ways to infect humans or evade vaccine protection.
Scientists remain focused on Delta, now the dominant variant that is growing rapidly in the world, but are following others to see what may one day take its place.
Delta variant
The Delta variant first detected in India remains the most worrying. It strikes unvaccinated populations in many countries and has been shown to infect a higher proportion of vaccinated people than its predecessors.
The WHO classifies Delta as a variant of concern, which means that it has been shown to be able to increase transmissibility, cause more serious disease, or reduce the benefits of vaccines and treatments.
According to Shane Crotty, a virologist at the La Jolla Institute of Immunology in San Diego, Delta’s “superpower” is its transmissibility. Chinese researchers have found that people infected with Delta carry 1,260 times more virus in their noses than the original version of the coronavirus. Some US research suggests that the “viral load” in vaccinated people who are infected with Delta is comparable to those who are not vaccinated, but more research is needed.
While the original coronavirus took up to seven days to cause symptoms, Delta can cause symptoms two to three days faster, giving the immune system less time to respond and defend itself. Delta also appears to mutate more, with reports of a “Delta Plus” variant, a subline that carries an additional mutation that has been shown to escape immune protection.
India listed Delta Plus as a variant of concern in June, but neither the US Centers for Disease Control and Prevention (CDC) nor the WHO have yet done so. According to Outbreak.info, an open source Covid-19 database, Delta Plus has been detected in at least 32 countries. Experts say it’s not yet clear if it’s more dangerous.
Lambda – declining?
The Lambda variant has gained attention as a potential new threat. But this version of the coronavirus, first identified in Peru in December, could be on the decline, several infectious disease experts have said Reuters.
The WHO classifies Lambda as a variant of interest, which means that it carries mutations suspected of causing a change in transmissibility or causing more serious disease, but it is still under investigation. Laboratory studies show that it has mutations that resist the antibodies induced by the vaccine.
Dr Eric Topol, professor of molecular medicine and director of the Scripps Research Translational Institute in La Jolla, Calif., Said the percentage of new Lambda cases reported to GISAID, a database that tracks variants of SARS-CoV-2 , has declined, a sign that the variant is in decline.
In a recent call with the CDC, disease experts said Lambda did not appear to cause increased transmissibility and the vaccines appeared to hold up well, said Dr William Schaffner, an infectious disease expert at Vanderbilt University Medical Center who attended the discussion. .
B.1.621 – to be monitored
The B.1.621 variant, which first appeared in Colombia in January, where it caused a major epidemic, has yet to gain a name in Greek letters.
The European Center for Disease Prevention and Control has listed it as a variant of interest, while Public Health England describes B.1.621 as a variant under study. It carries several key mutations, including E484K, N501Y, and D614G, which have been linked to increased transmissibility and reduced immune protection. So far, there have been 37 probable and confirmed cases in the UK, according to a recent government report, and the variant has been identified in a number of patients in Florida.
Others are in preparation?
Dr.Anthony Fauci, chief medical adviser to the White House, recently warned that the United States could be in trouble unless more Americans are vaccinated, as large numbers of unvaccinated people give the virus more than chances of spreading and mutating into new variants.
Advocates of greater international distribution of vaccine doses by rich countries say the same could happen as variants emerge unchecked among populations in poor countries where very few people have been vaccinated.
Even so, a key problem is that current vaccines block serious disease but do not prevent infection, said Dr Gregory Poland, vaccine researcher at the Mayo Clinic. This is because the virus is still able to replicate in the nose, even in vaccinated people, who can then transmit the disease through tiny aerosolized droplets.
Beating SARS-CoV-2, he said, will likely require a new generation of vaccines that also block transmission. Until then, the world will remain vulnerable to the rise of new coronavirus variants, according to Poland and other experts.
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