COVID-19 | Studies show vaccine protection waning

Experts say case graph can spiral up and possibly merge into a third wave

Updated - November 22, 2021 09:40 pm IST

Published - August 26, 2021 07:47 pm IST - Thiruvananthapuram

File photo of a COVID-19 vaccine for representation.

File photo of a COVID-19 vaccine for representation.

A steep rise in Kerala’s COVID-19 graph in the post-Onam period was a given, as buoyed by the feeling of safety afforded by vaccination, social interactions and multi-family gatherings were bound to happen, heightening chances of disease transmission.

The second wave in Kerala had never reached the baseline. The case graph, which had been maintained at a high plateau of 20-22,000 new cases daily, could spiral up and possibly merge into a third wave, many public health experts feel.

“We are now at a much higher baseline than we did when the second wave began rising but we do have some advantages this time as we have delivered at least one dose of vaccine to 88% of those above 45 years, while 43% has been fully vaccinated. We see clear indications that the disease has shifted to the younger age groups and that an estimated 10-15% of our new cases are vaccine breakthrough infections. This means that these are cases which normally would not reach hospitals and as long as our hospitalisations do not threaten the surge capacity, we should be able to manage this phase very well,” says T. S. Anish, epidemiologist and a member of the State’s experts’ committee on COVID-19.


Despite the rise in active cases, just about 15% of these cases are currently in hospitals. ICU and ventilator occupancy, regardless of some daily fluctuation, has been more or less steady over the past four weeks

However, even as the government hopes that vaccination will see it through the third wave, reports of waning vaccine efficiency from the US Centres for Disease Control, as well as the Oxford study should make the administrators question the prudence of its overemphasis on COVID vaccination, to the exclusion of other strategies and precautions that it should be adopting at this point of the pandemic.

Last week, CDC released data from three studies, which said that while vaccines helped to reduce the severity of the disease and deaths, the protection it afforded the individual against infection was progressively waning.

New York Times reported that “although fully immunized people of all ages got infected with the virus, vaccine effectiveness showed the sharpest drop, from 90.6% to 74.6%, in people aged 18 through 49 — who are often the least likely to take precautions and the most likely to socialise.

Researchers at the University of Oxford, UK, after analysing a vast data set of PCR results, concluded that though two doses of both Pfizer and Astra Zeneca (Covishield) offered good protection against Delta, this protection waned over time.

Astra Zenaca was 69% effective against a high viral load 14 days after the second dose but this fell to 61% by 90 days.

The study (published in a pre-print on August 19) reported that “vaccinated people who become infected with Delta carried high peak levels of virus and that people who have previously tested positive for COVID-19 as well as receiving two vaccine doses had the best protection against future infection”.

“This is quite concerning because Kerala has focussed on getting the first dose across to the maximum people, rather than protect all vulnerable and elderly with two doses first. It is possible that we might see reduced protection against severe disease, hospitalisation and death even amongst the fully vaccinated and this is something the Government should reckon and prepare for,” a public health expert said.

Data released by the Health Ministry of Israel last week suggested that people vaccinated in January (Pfizer) have just 16% protection against infection now, while in those vaccinated in April, the effectiveness was at 75%.

If vaccine potency wanes over time, then it would also mean that the thousands who got their first shot three months ago (the priority being for the elderly and those with co-morbidities) and are waiting for their second shot are more likely to be infected than what the Government reckons, in the current wave.

Kerala can in no way afford to bank on vaccines alone to see it through the pandemic and would have to seriously invest in preventing hospitalisations through better and improved home care.

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