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The United States Food and Drug Administration (FDA) has authorised the first redesigned coronavirus vaccines since the beginning of the pandemic in early 2020, which are intended to specifically target sub variants of Omicron.
The SARS-CoV-2 virus has mutated into many variants and sub variants since the first emergence of the “wild type” in China late in 2019, some of which have shown a considerable ability to escape immune response induced by both infection and vaccination. That is an important reason why, despite the sweeping second wave of the pandemic in the summer of 2021 as well as widespread double-vaccination in India, the third — Omicron — wave of the pandemic was able to infect a large number of people in the winter of 2021-22.
What are these new vaccines?
The FDA is calling the new vaccines “updated boosters”, and Americans could start getting the shots as early as next week. The US is still seeing 90,000 new infections and 475 deaths from Covid-19 every day on average, and the new vaccines are intended to add another layer of protection against the virus before the winter arrives.
Two updated boosters have been cleared, manufactured by Pfizer-BioNTech and Moderna. Both are “bivalent” vaccines, which means they contain two mRNA components of the SARS-CoV-2 virus, one of the original strain, and the other “in common between the BA.4 and BA.5 lineages of the Omicron variant”, the FDA said. The primary target of the updated boosters is the BA.5 sub variant, which is circulating freely in the US.
“The BA.4 and BA.5 lineages of the Omicron variant are currently causing most cases of Covid-19 in the US and are predicted to circulate this fall and winter. In June, the agency’s Vaccines and Related Biological Products Advisory Committee voted overwhelmingly to include an Omicron component in Covid-19 booster vaccines,” the FDA said in an official release.
“The idea here is not just to increase the antibodies right now, but also to hopefully give us a longer duration of protection” that will stay through the winter, FDA vaccine regulator Dr Peter Marks told a news conference on Wednesday (August 31).
Who can get these new shots?
The Moderna bivalent vaccine has been authorised as a single booster dose in individuals 18 years of age and older. The Pfizer-BioNTech bivalent, also a single shot, can be given to individuals aged 12 years and older.
Everyone who is fully vaccinated (double-jabbed) is eligible to receive the updated booster, even if they did not get the booster (third) shot. However, their last (most recent) shot — either the primary vaccination or the booster dose — should have been taken at least two months previously.
The first BA.5 case in India was reported in late May in Telangana, and Delhi reported its first couple of cases in the beginning of July. The BA.4 sub variant of Omicron too was detected in India at almost the same time, that is, in the beginning of May 2022. However, BA.5 spread faster, and had accounted for 7% of the sequences uploaded to the global GISAID database in the 30 days prior to the beginning of July.
More prevalent in India than BA.4 and BA.5 have been the BA.2.75 and BA.2.38 sub variants of Omicron.
According to INSACOG, the network of Indian research labs sequencing the genome of the virus, the percentage lineage frequency of BA.2.75 for August stood at 60.7%, compared with 20.6% in the previous month. This indicates that this particular sub variant of Omicron is currently driving the surge in the country. According to the data, the percentage lineage frequency of BA.2.75 in North India for August was at a significant 88.2%.
The current situation is different from the one prevailing a month previously. At the beginning of July, genome sequences uploaded to the global database GISAID showed that BA.2.38 — which branched off from the BA.2 sub variant of Omicron — was dominant in the country, accounting for 30% of all sequences over the previous 30 days.
That was followed by the BA.2 sub variant itself, and accounted for 28% of samples, showed an analysis of the GISAID data by outbreak.info. Outbreak.info is a project from Scripps Research that aggregates Covid data across scientific sources in order to track pandemic trends and integrate research and datasets into a single searchable library.
According to the WHO, the BA.2.75 sub variant has nine additional mutations in the spike compared to its parent lineage BA.2; four of these mutations are within the receptor binding domain (RBD), and at least one of these RBD mutations has been associated with immune escape in previous variants. Most significantly, the WHO has said that the majority of the reported sequences are from India.
