KOLKATA: Covid could turn more severe for those affected during the third wave of the pandemic, including for around 5% to 10% of third-wave patients who would be fully vaccinated by then, because of mutations like Delta and Delta Plus, experts have warned.
But, on the brighter side, the third wave itself could be much shorter than the second, with fewer catching the virus.
Experts fear that the mutations — first detected in India — could neutralise the protection provided by existing vaccines during the next wave, which is expected to strike between September and October.
Variations of the virus are the results of mutations that routinely take place during a prolonged pandemic, said Raja Dhar, director of pulmonology at CMRI.
But they are far more potent than existing ones, and the third wave will include these, he added.
“The virus changes to survive and even though these alterations are minor, they may turn out to be fatal, as the existing vaccines are not designed to counter them,” he told TOI.
“With the relaxation of restrictions, there will be more travel and transmission.
People from one city will infect those in another, which is called the ‘drift phenomenon’.
With every transmission, the virus changes and eventually this leads to variants.” He added that the ‘shift phenomenon’ — people from one country or region affecting those in others — could also be at work during the third wave.
“More severe pneumonia, fibrosis and cytokine storm are likely in the third wave,” he predicted.
Most mutations take place inside the ‘S gene’ or the spike protein, pointed out Bhaskar Narayan Chowdhuri, microbiologist, Peerless Hospital.
“In mutant strains, the S gene will be different from the previous strains.
Inactivated vaccines (such as Covaxin) seem to offer better protection against this.
But it has to be remembered that all vaccines offer some protection and may restrict the disease to a mild one,” said Chowdhuri.
He, however, warned that the Delta Plus variant was more transmissible and had been found to have an “affinity for lung tissues”.
“This could be dangerous since so far we have seen Covid affecting the upper respiratory system more than the lungs.
If the trend changes, the disease will be more severe and the mortality higher,” he said.
Souren Panja, an interventionist at RN Tagore International Institute of Cardiac Sciences (RTIICS), agreed with Dhar and called for screening of mutant viruses.
“The entry of Delta and Delta Plus has complicated the scenario.
These may not be cured by medicines that we are now using, namely remdisivir or steroids.
More importantly, vaccines may not stave off these strains, which could be dangerous.
So, we need wider screening facilities for mutants, which we don’t have now.” The saving grace was that the number of Delta cases were still few and restricted to a few states, adding, “The entire Covid strategy may have to be changed but unfortunately we may not have adequate time for that.” Dhar pointed out that according to a theory, it is advisable to vaccinate just 60% of the population, since that may prevent mutations.
“The more you vaccinate and resist the virus, the more it will change to survive.
It has started happening,” he said.