Safe, for now from new Delta variant of COVID19: Only 20 cases of AY.4.2 in India

AY.4.2 contains mutations that might give the virus survival advantages

India appears to be safe – for now – from a new descendant of the Delta variant of Covid19, which is causing a growing number of infections in the UK.

AY.4.2, which some are calling "Delta Plus", contains mutations that might give the virus survival advantages, experts in the UK say.

In India, researchers have reported 20 detected cases thus far.

They say, however, that much will depend upon Covid-appropriate behaviour during the festival season, which is currently underway in India.

A leading Indian virologist, Shahid Jameel, told Moneycontrol: ``The Delta lineage AY.4.2 is still a `variant under investigation’ because one, it has two additional mutations in the spike protein of the Delta lineage – S: A222V and Y145H. Both these mutations are outside the receptor-binding domain and laboratory data on their biological significance is still limited.” The receptor-binding domain allows the virus to lock into its host and, since this mutant is outside of this domain, there is less cause to worry.

Two, AY.4.2 accounts for a slowly increasing proportion of cases in the UK. It is also present in over 30 other countries and is seen in travellers to the UK from several countries. It is not clear where it originated or when, he said.

According to Jameel, AY.4.2 has a modestly increased population growth rate compared to Delta. This may be due to biological or epidemiological factors, which at this time is unclear.

The average secondary attack rate (SAR) for household contacts of cases with AY.4.2 is 12.4 percent compared to 11.1 percent for Delta. SAR measures the risk of a virus spreading through social interactions. Even in non-household settings it is higher for AY.4.2, but the difference is not statistically significant, he added.

What must be done

The bottom line, counselled Jameel, is for people to be cautious, especially during this festive season and to not let their guard down.

For policy makers, he said it is important to keep an eye on this variant through increased genomic sequencing and to see whether its prevalence increases or stays the same.

Rakesh Sharma, director, Tata Institute for Genetics and Society, said that the AY.4.2, which some are calling `Delta Plus’, could be a sub-lineage of Delta.

``In India, we have not yet seen a sub-lineage of Delta and at present, it poses no alarming threat. If we follow COVID-appropriate behaviour even in the festival season, there appears to be no real threat from this mutant, which is under watch in the United Kingdom,” he said.

Experts are not willing to make definitive statements on the variant because there is a lack of real-time information, he said.

Scientists of the INSACOG network monitoring the genomic variations in the SARS-COV-2 told reporters this week that a new mutated form of Covid-causing coronavirus, AY.4.2. that had caused panic in Europe as it is presumed to be more contagious than Delta, was present in India ``in very low numbers’’.

AY.4.2 is suspected to be the cause of the exponential rise in Covid-19 cases in the UK, Russia and Israel last week.

Scientists, however, admit that AY.4.2 related findings still carry a high level of uncertainty and it is still early to say that this lineage carries higher risk of severe illness or death.