Sanjeev Kumar Patro

News Highlights

  • XE is a BA.1 and BA.2 recombinant and has 3 mutations that are not present in all BA.1 or BA.2 sequences. The mutations are NSP3C3241T, V1069I and NSP12 C14599T.

With states like Delhi, Maharashtra and Haryana going for relaxations in masking at public places, the latest report from the UK calls for caution as a new variant of concern XE has been identified in the country.

As per UK Health security Agency, XE is a BA.1/BA.2 recombinant, with the majority of the genome including the S gene belonging to BA.2. XE shows evidence of community transmission within England, although it is currently less than 1 percent of total sequenced cases.

The report further said that by using the most recent data up to 16 March 2022, it has been found that XE has a growth rate of 9.8 percent above that of BA.2. BA.2 is the Omicron variant that had triggered the Third wave in India.

The data from the last fortnight of March 2022 shows that over 88 percent of sequenced cases confirmed Omicron BA.2 lineage. BA.1 constituted only around 10 percent. Other variants take a share of a mere 0.7 percent.

Covid-Recombinant On Stage

As per the UKHS, there are currently 3 recombinant lineages being monitored. They are XD, XE, and XF.

XD: It is a combination of Delta and BA.1. This recombinant has an Omicron S gene incorporated into a Delta genome. The unique mutations it has are NSP2 and E172D. It is present in several European countries but has not been detected in the UK. The recombinant is found majorly in France.

XF: This is also a combination of Delta and BA.1. Cluster cases of XF detected in the UK.

XE:  XE is a BA.1 and BA.2 recombinant and has 3 mutations that are not present in all BA.1 or BA.2 sequences. The mutations are NSP3C3241T, V1069I and NSP12 C14599T.  

Why This XE A Concern?

How come UKHSA has labelled XE a variant of concern when as of 22 March 2022, there are 637 cases in England?

By running a statistical model, it has inferred to a logistic growth of 0.5 per week. The report further explains that the variant is increasing by 1.65 per week vis-a-vis the control match.

"A logistic growth rate of zero would indicate no difference in the growth rate of the two variants. But the difference is estimated at 0.5," the report added.

The report concluded by saying, "After including the data sampled between 15 January 2021 and 15 March 2022, the relative frequency of genomes from the BA.2 lineage it was found that the median growth rate of XE is +9.8% per week."

What Is Recombinant Covid?

Biologically speaking, recombinant is an exchange of genetic material between genomes of two variants, especially when an individual has a dual infection. The risk with recombinant it has the potential to throw a 'Super Mutant' - highly contagious and lethal too.

Scientists Jensen and Lynch in a recent note in 'Heredity' have spoken about the 'mutation meltdown' strategy to restrict the expansion of Covid-19.

" If the virus were prevented from recombining, mutations might accumulate to the point that it becomes hampered or even unable to replicate and spread. The assumption here is drugs that interfere with recombination specifically could help end the pandemic," they wrote.

The Bottomline

In following the Covid appropriate behaviour, the benefit is that it will help in preventing the development of hybrid strain in India. The laggard shown after the first wave has led to the birth of a super variant of concern - Delta, that triggered a lethal second wave in the country.