Following the detection of Omicron as the new variant of concern, top genome scientists have recommended a booster dose of the Covid vaccine for those above the age of 40 years with priority for high-risk and high-exposure populations, according to the weekly bulletin of Indian SARS-CoV2 Genomics Sequencing Consortium (INSACOG), a network of national testing laboratories set up by the Government to monitor genomic variations of the virus.
“Vaccination of all remaining unvaccinated at risk people and consideration of a booster dose for those 40 years and above, first targeting the most high risk/high exposure, may be considered since low levels of neutralising antibodies from current vaccines are unlikely to be sufficient to neutralise Omicron, although the risk of severe disease is still likely to be reduced,” the INSACOG weekly bulletin says.
The bulletin also states that genomic surveillance will be critical for early detection of the new variant. It also recommends monitoring of travel to and from affected areas, contact tracing of cases with an epidemiological link to affected areas, and increased testing.
When contacted, some INSACOG members told The Indian Express that based on circulating genotypes and evolution of the virus, there is a “general belief” that prevailing immunity, either from infection or vaccine, might be low for the Omicron variant and there is a “good possibility” of reinfection. It is in this context that suggestions for a booster dose were made, they said while pointing out that INSACOG is not a decision-making authority.
Experts said the priority now should be ensuring that all those eligible are fully vaccinated first.
Noted virologist Prof Shahid Jameel told The Indian Express that for the moment, focus should be on getting as many people vaccinated as possible with two doses. He was responding to a question on the need for booster doses following the UK’s Cov-Boost phase 2 trial that showed six different boosters were safe and increased immunity when given after two doses of AstraZeneca (Covishield in India) or Pfizer-BioNTech.
“The COV-BOOST trial has tested a variety of combinations for boosters, including AstraZeneca, Pfizer, Moderna and Novavax vaccines. This will be a good guide for the National Expert Group on Vaccine Administration for Covid (NEGVAC) for future boosters in India,” Jameel said.
Gautam Menon, Professor of Physics and Biology, Ashoka University, said that the priority should be to ensure full two-dose coverage of the adult population. “After that or in parallel, prioritising a booster shot for those over-60, and the immuno-compromised of all ages, would be a sensible move,” he said.
Menon and other experts point out that the Cov-Boost UK trial showed a significant effect of a booster dose on antibody levels following two doses of the AstraZeneca vaccine against the Delta variant. However, there is no data available currently on how well a booster dose might work against Omicron.“This is also understandable as it has been discovered only recently,” Menon said.
Professor Rakesh Mishra, a scientist specialising in genomics and former director of CSIR- Centre for Cellular and Molecular Biology in Hyderabad, said that further trials and evidence need to be generated on how much a third dose can help.
“What is known is that vaccines are safe, and protect from severity and hospitalisation. Omicron is a wake-up call that the virus is going to be around and we need to keep up with surveillance. As far as vaccines are concerned, there is no debate — first give two doses and protect larger numbers that are unvaccinated,” he said.
“If we have adequate resources to give enough jabs at high speed, it is possible to administer the booster to healthcare workers and senior citizens with co-morbidities. However, there should be no shortage of vaccine and the first dose has to be given to all eligible beneficiaries,” Mishra said.