Third wave of Covid inevitable, says government
“A phase three is inevitable, given the high levels of circulating virus, but it is not clear on what time scale this phase 3 will occur."
India has detected a total of 3,532 Sars-CoV-2 variants of concern in 27 states, the government announced on Wednesday, adding that a third wave of Covid-19 was inevitable looking at the current surge in infections.
Researchers have found that the circulation of the UK variant (B.1.1.7) that is known to be 50% more transmissible is on a decline in India, and the double mutant variant (B.18.104.22.168) is on the rise, said senior scientists.
“A phase three is inevitable, given the high levels of circulating virus, but it is not clear on what time scale this phase 3 will occur. Hopefully, incrementally, but we should prepare for new waves. Previous infections and vaccines will cause adaptive pressure on the virus for new kinds of changes which try to escape, and, therefore, we should be prepared, scientifically to take care of that,” said K Vijay Raghavan, principal scientific advisor, to the government of India.
Those mutations are a variant of concern for which there is evidence of an increase in transmissibility, more severe disease etc.
He also said that scientists were currently making a map in the laboratory of all possible changes that could happen to the virus and see how these changes could affect immune and vaccine evasion.
Many factors contributed to this second wave and variants are one of the factors, Vijay Raghavan said.
The first wave peaked in September last year and declined because of two factors, he said. “As infections rose, so did immunity among those infected. A combination of the standing level of immunity in the population and cautionary steps halted the spread of the first wave,” he said.
But as the cautionary steps declined, new opportunities for infection arose and the level of immunity among the population is often not enough to stop the infection spread. “Many people get infected until they reach a new immunity threshold. Such a second wave is typically smaller than the first. Such a second wave was expected. However, multiple parameters can change and add up to the second wave, much larger than the first.
“(But) Such a larger second wave with the ferocity we are seeing was not predicted,” he said.
The consortium of 10 advanced laboratories that is performing genome sequencing of positive samples across the country since December 2020, found that the UK variant (B.1.1.7) of Sars-Cov-2 that was dominating till some time ago, is on a decline in the country, and it is the double mutant variant (B.1.617) that is gradually gaining prominence.
“We have seen the B.1.1.7 lineage that was quite prevalent in the initial period especially in states such as Maharashtra and later Delhi, is declining in proportion during the last one-and-a-half month. As of today, our B.22.214.171.124 lineage that was initially centred initially around Maharashtra, is now detected in many other states. And in some states, we have established its correlation with the current surge. However, its epidemiological and clinical correlation needs to be established yet,” said Dr SK Singh, director, National Centre for Disease Control, Delhi.
Three-four states had shown higher variant load, including Maharashtra, Punjab, Delhi, Andhra Pradesh and Telangana, said Dr Singh in his presentation
Experts also said that more than higher transmissibility, it is the clinical correlation that was crucial. “INSACOG [Indian Sars-Cov-2 Genome Sequencing Consortium] data just shows that variants, especially the B.1.617 may have some advantage in the spread, but what that has to do with phase 3 remains to be seen.,” said Dr Gagandeep Kang, professor at Christian Medical College, Vellore. Singh added, “At least 1.3 million mutations have been notified globally so far in Sars-cov-2, and not all mutations are of concern...”