‘Low sero-positivity level makes Kerala’s children vulnerable’

Thiruvananthapuram | Updated on October 13, 2021

Expert warns of Covid clusters in schools; positivity rate in adults at 82.6 per cent

The long-awaited results from Kerala’s own sero-prevalence survey may have returned a creditable 82.6 per cent positivity among its adult population, but a leading public health analyst has advised caution against the State lapsing into any misplaced sense of complacency.

Dr Anish S, Member, Kerala State Covid Task Force, and Assistant Professor, Community Medicine, Government Medical College, Thiruvananthapuram, pointed to a ‘sobering revelation’ ringing out loud in the survey – low positivity of just 40.2 per cent among children. This is one of the lowest in the country, especially in those areas that saw community transmission.

Raised risk profile

The fourth ICMR sero-survey conducted in May had assessed a sero-prevalence of as high as 55 per cent among children – this means updated figure for Kerala in its own sero-survey in September is at least 15 per cent lower even after lapse of four months.

“One positive aspect is that we may have successfully protected our kids from infection for this long at a time when no vaccine were available. Children may not be an epidemiological risk group, but to protect them during community transmission is a great virtue viewed from a societal perspective,” Dr Anish told BusinessLine.

The flip side is that since 60 per cent of them do not have antibodies, there’s a distinct possibility that Covid clusters may form in schools. This is unlike the situation elsewhere in the country where schools reopen with an embedded advantage in terms of much higher sero-prevalence and therefore the kids are safe.

School-led spread

“It is also known that infections do not become serious among kids, nor does Kerala have any reported instance except in comorbid children. So, comorbid children may better confine themselves to home and attend online classes. Parents must be vigilant against their bringing home the virus in the unfortunate event of the school reporting a cluster.

The 82.6 per cent cent sero-positivity among adults compares strikingly with the 44 per cent detected in the ICMR survey in May.

“This means that sero-prevalence in Kerala has almost doubled within a space of four months. In May, only 30 per cent of the eligible population had received the first dose of the vaccine. But during the first week of September when the sero-survey was being carried out, the vaccine coverage had grown to 80 per cent (this is now 93 per cent-plus),” Dr Anish recalled.

So, there was a jump of 50 per cent in vaccine coverage, which was also the highest so far for any comparable period. A good percentage of sero-prevalence is thus contributed by Covid vaccination.

The State had also witnessed some of the highest instances of spread of the Delta variant during this period even as infections moderated drastically in other States. In this manner, natural infections may also also have contributed to the enhanced sero-prevalence in the State.

“I would love to call it a hybrid model of sero-positivity or immunity. This is a desirable situation, and a good augury. This should hopefully go to rule out any intensified spread, provided we don’t have any genetic variant from an enhanced Delta variant spread. Test positivity ratio (TPR) should dome down progressively. It had come down to single digits on Tuesday after three months,” said Dr Anish. Breakthrough infections

There is a caveat here, too. Kerala will still have to contend with the threat of breakthrough infections among the vaccinated. “This is because the Covid vaccine has been developed from the strain that led the spread in February-March 2020, much before the hyper-infective Delta variant struck. So, this naturally means the vaccine will not be able to prevent Delta infections by any significant margin,” said Dr Anish.

At best, it prevents cases from worsening, maybe even avoid deaths, too. But the sero-converted through vaccination still runs the risk of an infection, though mild. it will be manifest at best as a common cold that will not threaten life. “All in all, one can attribute the high sero-prevalence to Kerala’s success in the prolonged fight against Covid virus and may help it achieve a sustainable reduction indaily new cases.”

Published on October 13, 2021

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