Health officials and scientists are closely tracking a new mutation of the coronavirus amid concerns that it could be more transmissible than the original strain.
A subvariant of the Delta variant of the virus labelled AY.4.2 has been detected in dozens of countries, with the vast majority of cases being reported in the United Kingdom.
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“An increase in AY. 4.2 sequence submissions has been observed since July,” the World Health Organization (WHO) said in its weekly epidemiological update this week.
It said that 93 percent of AY.4.2 cases were reported in the UK, where the strain was gradually contributing to a greater proportion of cases and accounted for about 5.9 percent of overall Delta cases reported there in the week beginning October 3.
“Epidemiological and laboratory studies are ongoing” to assess if there has been a change of transmissibility or a decrease in the effect of the antibodies to repel the virus, the United Nations health agency added.
The UK’s Health Security Agency (UKHSA) last week labelled AY.4.2 as a “variant under investigation,” but despite its spread, it has not yet been labelled as a “variant of concern”.
Here is what we know so far:
What is the new AY.4.2 strain?
The subvariant is an evolution of the highly transmissible Delta variant of the coronavirus. Scientists have found three mutations including two in the spike protein, the part of the virus that allows it to bind to and invade the body’s cells.
The subvariant, which some have labelled as “Delta Plus,” contains changes that could give the virus survival advantages over other variants.
Previously, variants have fuelled new surges in coronavirus cases. The Alpha variant spread widely after it was discovered in the UK in late 2020, and the Delta variant has become the dominant strain of the virus worldwide since it was discovered in India in late 2020.
However, experts have noted that AY.4.2 has not become the dominant strain in the countries where it has been reported.
“Currently, the strain has been found in some other countries, but it is not becoming predominant,” Dr Roselyn Lemus-Martin, who holds a PhD in molecular and cell biology from the University of Oxford, told Al Jazeera.
“It’s possible that we see a situation similar to the Lambda strain … at the start, people were concerned but eventually its presence was diluted in places like the US or the UK,” she added.
Experts have also noted that similar mutations have been witnessed in other variants and other lineages of the Delta variant, without having a large effect on the virus.
The Delta variant remains “by far the most dominant variant in terms of global circulation”, Maria Van Kerkhove, the World Health Organization’s epidemiologist, said at a public session in early October.
“Delta is dominant, but Delta is evolving,” she said, adding that the more the virus circulates, the greater the chances it has to mutate.
Is AY.4.2 more transmissible than Delta?
It is still unclear “whether it is more transmissible or whether it is more capable of evading any immunity that we have through the vaccination,” Dr Patrick Tang, the Division Chief of Pathology Sciences at Sidra Medicine in Qatar told Al Jazeera.
“We don’t have enough data to point one way or another.”
Experts warned that the spread of the variant could be the result of a number of factors, including public health measures set out by governments or adherence to those measures.
“The minor changes in the virus are almost never causing an increase in transmission. The increased transmission … is really an indication of public health response or compliance to public health measures,” he added.
According to Lemus-Martin, it is not clear whether its spread in the UK is a result of with biological reasons or if it is linked to the “epidemiological conditions in the UK”.
“In the UK the current measures against COVID-19 are very lax, practically they are not following them anymore, and we don’t know if that might be the reason for the spread,” she added.