Dr. Vijay Warad, MBBS, MD-Allergist, Clinical immunologist, Paediatric pulmonologist.
The Omicron variant of COVID-19 has been known as a variant of concern by WHO. Omicron is spreading quicker than any previous variants, with the country reporting 2,897 cases on Thursday. The overall risk related to this variant remains very high. BA.2 is a subvariant of Omicron sometimes referred to as “stealth Omicron”. It is presently the dominant strain of COVID-19 globally and in India as well and is the most contagious variation of the virus to date, as per the World Health Organization. BA.2 isn’t viewed as more severe than the other types of Omicron, but with the huge increase in the number of cases, there has been an increase in hospitalizations in nations all over the world. Many nations which have eased their COVID safety protocol, like the use of masks and physical distancing, are adding to the spread of the virus.
BA.2 differs from BA.1 in its genetic sequence, including some amino acid differences in the spike protein and other proteins. Studies have shown that BA.2 has a growth advantage over BA.1. Studies are ongoing to understand the reasons behind this growth advantage, but initial data suggest that BA.2 appears inherently more transmissible than BA.1, which presently remains the most common Omicron sublineage reported. This difference in transmissibility appears to be much smaller than, for instance, the difference between BA.1 and Delta. Further, although BA.2 sequences are increasing in proportion compared with other Omicron sublineages (BA.1 and BA.1.1), there is still a reported decrease in overall cases around the world.
Studies are evaluating the risk of reinfection with BA.2 compared with BA.1. Reinfection with BA.2 following infection with BA.1 has been documented, however, initial data from population-level reinfection studies proposes that infection with BA.1 provides strong protection against reinfection with BA.2, at least for the limited period for which data is available. Hospitalizations among children might seem concerning, but estimates show that the individual risk of a child with Omicron being hospitalized is, in fact, lower — by one-third to one-half — than it was when the Delta variant was dominant.
The COVID-19 vaccines are still showing strong protection against severe diseases, including Omicron. There are various vaccines currently available: –
- COVAXIN: Covaxin is developed with Whole-Virion Inactivated Vero Cell-derived technology. The Covaxin booster dose trials showed promising results. High neutralizing capacities of the Covaxin boosted sera samples against the SARS-CoV-2, as well as the Omicron variants, were evaluated using the live virus focus reduction neutralization test (FRNT).
- COVISHIELD: Covishield utilizes modified spike proteins from a chimpanzee adenovirus to elicit an immune response against this protein of the virus. Developed in collaboration with researchers from the University of Oxford, the AstraZeneca vaccine’s third dose could help improve antibody response in countries where Omicron is causing record cases.
- SPUTNIK LIGHT: Based on the data collected by the Spallanzani Institute and results of previous studies, heterologous (“mix and match”) boosting with Sputnik Light is the best solution to increase other vaccines’ efficacy and extend the booster protection period as optimal adenoviral platform configuration provides better protection against Omicron and other variants.
The COVID-19 pandemic is still causing considerable high mortality rates, putting a significant burden on healthcare services worldwide and having profound economic and social consequences due to the different strategies implemented to control the virus. Three waves have hit the world strongly till now but let us make sure now that we do everything on our part to curb the spread of virus. Wearing masks, practicing social distancing, and getting jabbed sure looks to be the safest way forward for all of us.