Omicron Threat: Efficacy of Booster for Omicron

Author: G C Khilnani Chairman, PSRI Institute of Pulmonary, Critical care and Sleep Medicine. Formerly, Professor and Head, Dept of Pulmonary Med AIIMS, N Delhi

Booster Vaccination to prevent COVID-19 in the era of OMICRON
Association between 3 Doses of mRNA COVID-19 Vaccine and symptomatic infection caused by the SARS-CoV-2 Omicron and Delta Variants

India

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New Delhi, January 23, 2022:

According to JAMA (Journal of American Medical Association), 22nd January,2022

Overall, 23 391 cases (13 098 Omicron; 10 293 Delta) and 46764 controls were included
Those who receive three doses. Omicron in infection occurred in 18.6% as compared to as compared to 55.3 % (two dosages)
Those with three dosages the Delta infection was in 6.6% as compared to 44.4 % (two dosages)
These findings suggest that receipt of 3 doses of mRNA vaccine, relative to receipt of 2 doses, was associated with protection against both the Omicron and Delta variants, although the protection rate was higher for Delta infection. New York Times Omicron Threat Efficacy of Booster for Omicron
Vaccine effectiveness against hospitalization with the Omicron variant fell to just 57 percent in people who had received their second dose more than six months earlier, the authors found. A third shot restored that protection to 90 percent.

According to Dr G C Khilnani, By January 1, 2022, Omicron was estimated to be responsible for 95% of new cases in USA. India is also following the same trend. Therefore, it is important to know the effect of third dose of vaccine for protection against Omicron infection and hospitalization. This study has clearly shown that third dose of vaccine leads to protection against Omicron infection as compared to two dosages, however, efficacy it is less than that for Delta variant. This stands to reason as vaccines were prepared much before Omicron variant which has more than thirty mutations on spike protein. The silver lining is that third dose gives protection against hospitalization to the tune of 90%.

USA is still having daily average case count of more than eight lacs. Considering the population of India (5 times) , it would be 40 lacs /day, if we extrapolate. Given the contagiousness of Omicron, it is not possible to completely stop the spread. However, all efforts should be made to reduce transmission by Covid appropriate behavior so that the medical care system is not overwhelmed as we have large pool of susceptible population who have a threat of hospitalization and death even with Omicron Infection.
As India has done phenomenally well on vaccination with more than 90% adults having received one shot, a third dose to susceptible population will protect our vulnerable group from getting infection and more sosevere disease. There is significant advances in therapies to prevent severe disease by timely institution of antiviral drugs (Molnupiravir, Remdesivir ) and antibody cocktail (Monoclonal antibodies) which should be used judiciously to achieve ZERO mortality with Omicron infection.
In India initial hesitancy was replaced with enthusiasm for vaccination among masses. Low incidence of severe disease with Omicron should not make us complacent for receiving third dose which gives us protection from infection and more so from severe disease. We all know that there is always a threat of `new variants’ and it is expected that being fully vaccinated (with third dose) would protect us from them too

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