Vaccine Efficacy on Omicron

Since 2019 the world has been battling the COVID-19 pandemic. COVID-19 is caused by the severe acute respiratory syndrome coronavirus, also known as SARS-CoV-2. COVID-19 is a severe health problem affecting the respiratory system. Not only that, but it is also a highly infectious disease. Multiple variants with varying degrees of infectivity and fatality have emerged since the beginning of the SARS-CoV-2 pandemic. Starting with the Alpha, Beta, Gamma, Delta, and then Omicron, associated with greater transmissibility and severity (Aleem et al., 2022; Khandia et al., 2022). All of these were categorised as ‘Variants of Concern’ by WHO.

The Omicron Variant

Omicron – the variant that was most fervently discussed in the media recently, is also being widely researched by experts worldwide. It has shorter incubation periods and milder clinical symptoms. On comparing the infectivity of the Omicron variant of SARS-Cov-2 with earlier strains, we find that it is ten times more infective than the original virus and two times more infective than the Delta variant (Chen et al.
Since the outbreak of SARS-Cov-2 in 2019, Omicron has evolved due to the accumulation of the maximum number (50) of mutations (Khandia et al., 2022). More than 30 mutations have been discovered in the virus’s receptor-binding domain (spike protein) itself. This property of Omicron makes natural immunity and the efficacy of existing vaccines on this strain questionable (Aleem et al., 2022; Khandia et al., 2022). The antibodies generated against the previous strains have a substantially lower likelihood of neutralising the omicron virus, indicating an escape of natural immunity (Khandia et al., 2022).

What are Current Vaccine Efficacies on Omicron

Research suggests that the reduced vaccine efficacy for the omicron variant could be because of a high degree of mutations in the region that binds to neutralising antibodies. It weakens the human body’s immune response to Omicron (Callaway and Ledford, 2021). Interestingly, vaccination after natural infection produces more natural antibodies against Omicron as compared to vaccination prior to infection. (Callaway, 2021; Schmidt et al., 2021)
People with a history of infection were more protected against Omicron than people who had never encountered the virus. Cele et al., 2021 also reported that ancestral viral neutralisation was 22 times higher among vaccinated and previously infected people than omicron virus neutralisation. The efficacy of the vaccine was 73% (95% CI 58–83%) in people who were vaccinated and had previous exposure to the virus, while it was only 35% (95% CI 20–50%) in vaccinated individuals with no history of infection (Cele et al., 2021).
As the virus evolves and we find new strains emerging worldwide, customisation and modification of the vaccines are much required. Vaccine manufacturers need to keep updating themselves about the efficacy of vaccines vis-à-vis new strains. Premediated action is essential to limit the dire repercussions that may arise due to the introduction of new mutant varieties.

The Way Ahead

The continuous evolution of SARS-CoV-2 and the emergence of new variants has led to one of the longest pandemics in human history. The persistence of COVID-19 has put the entire world in a grim situation, severely affecting human health and wreaking economic havoc worldwide (Petersen et al., 2022).
However, Jesse Bloom, a renowned evolutionary biologist, has predicted that the Omicron variant of SARS-CoV-2 will never be entirely eradicated. Instead, it may become endemic and may end up permanently established in the human body, just like many other viruses. It will be a seasonal virus that causes relatively mild colds (Ewen Callaway, n.d.).
The emergence of Omicron has put our world on the brink of severe global health concerns. We all have a moral obligation to limit the transmission of the virus by following COVID specific guidelines. Everyone should implement safety measures like social distancing, wearing face masks, hand hygiene, respiratory hygiene, and following quarantine guidelines. It is the best way to support the global battle against the pandemic and reduce the economic burden. On their part, governments across the world must strive to improve medical facilities and develop more effective vaccinations that work against all the different strains of SARS-CoV-2.


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