Beyond Delta, Scientists See New Variants Of Coronavirus

CHICAGO – 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 in the world, but follow others to see what may one day take its place.

Delta still dominant

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 U.S. research suggests that the viral load in vaccinated people who become 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.

Lambda in decline

The Lambda variant had gained attention as a potential new threat, but this version of the coronavirus, first identified in Peru in December, appears to be receding.

Although cases involving Lambda increased in July, reports of this variant have declined worldwide over the past four weeks, according to data from GISAID, a database that tracks variants of SARS-CoV-2.

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.

Mu is to watch

Mu, the variant formerly known as B.1.621, was first identified in Colombia in January. On August 30, the WHO designated it as a variant of interest due to several disturbing mutations and gave it a name in Greek letters.

Mu carries key mutations, including E484K, N501Y, and D614G, which have been associated with increased transmissibility and reduced immune protection.

Mu caused larger epidemics in South America and Europe, according to the WHO Bulletin published last week. While the number of genetic sequences identified as Mu has fallen below 0.1% worldwide, Mu accounts for 39% of the variants sequenced in Colombia and 13% in Ecuador, places where its prevalence has “steadily increased”, a WHO reported.

The World Health Agency said it continues to monitor Mu for changes in South America, especially in areas where it co-circulates with the Delta variant. Maria van Kerkhove, head of the emerging diseases unit at WHO, said the circulation of the variant is declining around the world but needs to be watched closely. During a press briefing last week, White House chief medical adviser Dr Anthony Fauci said U.S. authorities were monitoring him, but so far Mu is not considered a immediate threat.

Others are in preparation?

Getting more people vaccinated against COVID-19 is essential because large groups of unvaccinated people give the virus more opportunities to spread and mutate into new variants.

This effort must be intensified at the international level to prevent variants from appearing unchecked among populations in poor countries where very few people have been vaccinated, according to experts.

Even so, while current vaccines prevent serious illness and death, they do not block infection. 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 will likely require a new generation of vaccines that also block transmission, according to Dr Gregory Poland, vaccine developer at the Mayo Clinic. Until then, according to Poland and other experts, the world remains vulnerable to the rise of new variants of the coronavirus.