BA.5 here, but no major threat yet
Doctors in India too said that the variant appears to be causing illness similar to what other Omicron lineages have been doing – that is, infections have been symptomatic but without severe outcomes, although the spread has been rapid.
The first of BA.5 variant infections were recorded in the national capital, people aware of the matter said on Monday. A sub-lineage of the Omicron variant, which swept across the world, including India, at the beginning of this year, BA.5 has triggered some concerns for its key trait of being significantly more resistant than past ancestral lineages.
What is the worry?
This configuration of the virus appears to be displacing others of the Omicron variant. Anytime a variant does that, it can mean either of two things – the virus is more infective, or it is more resistant to immunity from a past infection or vaccination. In BA.5’s case, the suspicion is on the latter.
Epidemiologically, BA.5 first sparked a resurgence in infections in South Africa and Portugal. South Africa was ground zero for the first Omicron wave in November, 2021 and the coronavirus has since evolved significantly further from that variant too.
Even then, however, South Africa’s hospitalisation rates in the BA.5 were significantly lower than what was recorded last year, which itself was lower than what was seen during past outbreaks, such as those triggered by the Delta variant.
Doctors in India too said that the variant appears to be causing illness similar to what other Omicron lineages have been doing – that is, infections have been symptomatic but without severe outcomes, although the spread has been rapid.
Why does it have these traits?
Biologically, BA.5, along with its sister lineage BA.4, has two particular mutations in its receptor binding domain (RBD) – L452R and F486V. These two are loosely being implicated in the uniquely resistant trait that BA.4 and BA.5 seem to demonstrate.
Scientists are carrying out biological studies to see if there is more reason to worry – a question that will particularly look at how, if at all, it binds to cells in the lungs, where the Sars-CoV-2 can cause most damage.
How far has it spread in India?
According to sequences submitted by Indian labs to the global GISAID repository, 120 samples have tested positive for BA.5 since May 1, the first time the variant was detected in the country. The highest number of the samples were collected from Tamil Nadu and Karnataka, both of which recorded 43 positive samples each. Telangana has detected 21, Maharashtra 11 and Gujarat one.
These figures, to be sure, are as likely to be reflective of actual prevalence as they are of prompt sequencing and sampling – states where genome analysis is done more promptly are naturally likely to detect a new variant before a region with patchy surveillance.
Both Tamil Nadu and Kerala have recorded a spurt in infections in the last two weeks, but the hospital admission rates have not shown any concerning rise.
Who is at risk?
Like with all variants, those without a past infection and vaccination have the lowest baseline immunity, and are therefore at the highest risk. But some studies have also shown that those with a past BA.2 infection are likely to have a slightly greater protection than those with the BA.1 variant infection.
While it is difficult for an average person to determine what variant they were infected by, an approximate rule of thumb is that infections that took place early in 2022 – especially first couple of weeks in January – were likely caused by older Omicron lineages like the BA.1. The BA.2 is estimated to have become dominant in India beginning in late January.
