The Brihanmumbai Municipal Corporation (BMC) on Wednesday (April 6) announced that a 50-year-old woman with a travel history to South Africa may have been infected with the newly-discovered ‘XE’ variant of the coronavirus.
XE, a sub-variant of Omicron, which caused the third wave of Covid-19 this winter, had not been found in India until now. The announcement about its discovery sparked concern about the possibility of a fresh wave of infections in India, where Covid-19 cases are in continuous decline, and are now at their lowest level in more than two years.
Almost immediately, however, Union Health Ministry sources in New Delhi clarified that the identification of the XE variant in that particular patient was yet to be confirmed. In fact, a preliminary analysis had suggested that the virus detected in the patient was not the XE variant.
A confirmation one way or the other was expected in a day or two.
The Omicron variant, which is responsible for over 90 per cent of the infections detected this year, has two prominent sub-variants, called BA.1 and BA.2. There is a BA.3 sub-variant as well, but that is less common.
During the initial phase, the BA.1 sub-variant was the most widespread. In India, however, it was the BA.2 that was the most dominant during the third wave.
BA.2 was found to be slightly more transmissible than BA.1, even though it was not more dangerous. In the last couple of months, the BA.2 variety has become the most widespread across the globe, accounting for almost 94 per cent of all Omicron infections in the last one month, according to the World Health Organisation (WHO). The incidence of the BA.1 variety is declining sharply.
The XE variant is what is called a ‘recombinant’. This means it contains the mutations found in BA.1 as well as BA.2 varieties of Omicron. This was first discovered in the United Kingdom in January, and so far more than 600 samples of XE have been found in different countries.
Recombinant variants are not uncommon. Variants that contain mutations characteristics of two or more known variants occur all the time. In fact, variants that contain the characteristic mutations of Delta and Omicron have also been identified.
The random process of genetic mutations in viruses and other organisms keeps happening continuously. But only a small fraction of these mutations significantly alter the abilities of the virus to infect, or to cause severe diseases.
“Given the current high level of transmission worldwide, it is likely that further variants, including recombinants, will continue to emerge. Recombination is common among coronaviruses and is regarded as an expected mutational event,” the WHO said in a recent update.
As of now, there is no evidence to show that the XE variant is significantly different from the other varieties of Omicron.
What has been noticed is that XE could be about 10 per cent more transmissible than the dominant BA.2 variant. But that is a very small advantage that XE has, and even this has not been confirmed as of now.
The fact that there has been no significant increase in the incidence of the XE variant since its detection three months ago shows that it might not be a big worry at present.
The clinical manifestation of the XE variant has not been found to be any different from BA.1 or BA.2. It has, so far, not been found to cause a more severe form of the disease compared to other Omicron varieties. As such, the XE variant is not being considered different from Omicron.
“XE belongs to the Omicron variant until significant differences in transmission and disease characteristics, including severity, may be reported,” the WHO said.
It would not be surprising if the XE variant is indeed found in India — in the Mumbai woman, or in some other patient at a later stage. Travel restrictions have been mostly done away with, and international air travel is back to almost where it was in the pre-pandemic period.
Also, the possibility of XE, or any other recombinant variety of Omicron, developing within the Indian population cannot be ruled out. It is also possible that the XE variant is already circulating in the Indian population, but is yet to be detected.
However, the mere detection of the XE variant does not, on its own, trigger worries of a fresh wave in the country. As of now, it is not very different from the Omicron variant. Unless it develops special abilities to infect, bypass immunity, or cause a more severe form of disease, the threat from the XE variant to the Indian population is quite low right now.
Can Indians breathe easy, therefore?
The fact is that a fresh wave of infections in India can never be ruled out, considering that the virus has not been eliminated, and is also undergoing mutations.
But in the absence of the emergence of a new variant, that is either much more transmissible, has special abilities to bypass the immunity gained by human beings from prior infection, or causes more severe disease, this situation seems unlikely in the near term.
That is mainly because a very large proportion of the Indian population, an estimated 40 to 50 per cent, has very recently been infected by the Omicron variant. The immunity gained from that infection is likely to be still effective. Reinfection from the same variant is not unknown, but not very common either.
A fresh wave in the near future, if it comes, would most likely be caused by a new variant that is not very similar in characteristics to the Omicron variant. And the XE variant might not be that candidate, considering what is currently known about it.
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