As more evidence emerges on the immune escape potential of B.1.617.2, the SARS-CoV2-virus variant sweeping across Kerala, and the lowered effectiveness of current vaccines against it, the State should initiate clinical observation studies on the disease profile of those who are infected with the virus variant so that evidence-based changes can be made in the vaccine policy.
B.1.617.2, an extremely transmissible virus Variant of Concern, has emerged as the dominant strain across the State.
Last week, the U.K., where B.1.617.2 has been spreading far and wide, announced that it was accelerating the vaccination of those above 50 years following new evidence that one dose of Astra Zeneca (Covishield in India) vaccine had only 33% effectiveness against the variant.
Interval reduced in U.K.
The U.K. shortened the dosage interval of the said vaccine from 12 weeks to eight weeks, whereas two doses boosted effectiveness to nearly 60%.
According to a new pre-print released on May 26 by scientists from Pasteur Institute, France, the SARS-CoV-2 variant B.1.617.2 was less sensitive to monoclonal antibodies and sera from convalescent and vaccinated individuals, making it an immune escape mutant. It said that sera from individuals having received one dose of AstraZeneca vaccine barely inhibited B.1.617.2.
Unlike in the case of other vaccines, COVID vaccines cannot prevent infections. But if a vaccinated individual gets infected, he is protected from serious disease or death.
“In the field, the State has not studied or documented the clinical profile of those who got COVID-19 after receiving one or two doses of vaccine. This is important as it tells us about the level of protection the vaccine offers and if one dose is enough to prevent disease severity,” says E. Sreekumar, senior scientist (Virology) at Rajiv Gandhi Centre for Biotechnology (RGCB).
At a time when vaccines are in short supply, real world data or evidence from the field can go a long way in helping the government take crucial decisions on the State’s vaccine policy.
Appropriate strategy
Studying the clinical profile of those who got infected after receiving one or two doses of vaccine will give a clear indication as to the level of protection that a first dose and a second dose offered. If the first dose was enough to prevent serious disease and hospitalisation, then it should help the authorities decide whether covering as many people as possible with at least a single dose vaccine is the appropriate strategy for the State, it is pointed out.
In fact, with 80% of the five lakh plus health-care workers in the State having already received two doses of COVID-19 vaccine, they would form an ideal cohort in whom these studies can be done. Despite receiving two vaccine doses, hundreds of health-care workers have been testing COVID positive in the State.
Since April, the virus variant B.1.617.2 has been sweeping across the State like wild fire, affecting all susceptible individuals and vaccination does not seem to have been able to stop its spread. The RGCB has been doing genetic sequencing of samples from southern districts since May and of the 80 plus samples analysed so far, 95% has been B.1.617.2.
Dominant strain
“This variant is likely to remain the dominant circulating strain because there is no resistance in its path to stop it. Even fully vaccinated individuals could have sub-clinical infection and while they may not be at high risk, they could still transmit the infection. Universal masking is not something we can give up any time in the near future,” Dr. Sreekumar says.
