Dr Haryax Pathak, Member, iCart explains that regular booster doses may be required to pump up the efficacy of the vaccine and protect us from any new variant that might lead to another wave
While the recent Omicron wave fuelled the number of COVID cases in the country, it taught us that this pandemic is far from over. Since Omicron was less life-threatening, according to popular belief, the pandemic may gradually be shifting towards an endemic. But with constant mutations that may not be the case. RNA viruses, such as the SARS-CoV-2, are defined by a high mutation rate, one million times higher than their host. Wherever the virus travels, it mutates. With thousands of mutations, there is always a risk of a new variant that may be more dangerous than the previous one.
Vaccines are made after thoroughly studying the gene-sequencing of each variant. Mutations occur in areas such as the receptor-binding domain (RBD), and vaccines and antiviral drugs are formulated by targeting more than one viral protein. With the virus constantly replicating itself, this process of keeping up with the mutations becomes difficult. However, as we follow COVID safety protocols we can protect ourselves from the virus to an extent. Getting vaccinated and developing herd immunity remains to be our best shot to survive this pandemic. Even after this, regular booster doses may be required to pump up the efficacy of the vaccine and protect us from any new variant that might lead to another wave.
According to WHO, in India, 58.1 per cent of the population is double vaccinated while 72.2 per cent of people have only got their first dose. India flagged off the vaccination for 15-17 years in January 2022. Talking about the vaccines available in the market, Covishield, Covaxin along with Sputnik V and Sputnik light are the ones that are currently being administered. Now that the focus of the healthcare industry slowly shifts towards booster dosages, the government has allowed the administration of “precautionary doses”. Let us briefly cover the 3 main booster shots available in India.
The Covaxin booster dose showed promising results in its booster dose trials with more than 90 per cent of all individuals boosted with Covaxin. The booster dose had efficacy being maintained for a period of 6 months. The boosted subjects showed high neutralizing activity against the Omicron variant.
Positive results from a preliminary analysis of an ongoing safety and immunogenicity trial showed that Vaxzevria (COVISHIELD in India), when given as a third dose booster, increased the immune response to Beta, Delta, Alpha, and Gamma SARS-CoV-2 variants, while a separate analysis of samples from the trial showed an increased antibody response to the Omicron variant.
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 recently approved Sputnik Light is based on recombinant human adenovirus (medium-sized, nonenveloped) serotype number 26 (the first component of Sputnik V). A one-shot vaccination regimen of Sputnik Light provides for ease of administration, helps to increase the efficacy and duration of other vaccines when used as a booster shot. This will further make an important contribution to the country’s vaccination program.
In a recent study in ACS Infectious Diseases, with the help of an AI-based model, it was found that mutations strengthen the virus’s R number and are one of the driving factors for viral evolution. The researchers also predicted that certain combinations of mutations have a high likelihood of massive spread. That being said, the onus falls on us to protect ourselves from the virus. The longer a virus stays in circulation in the human population, the more chances it has – to adapt, mutate, and evolve into different variants. The focus, therefore, must be on reducing the transmission of the virus to the bare minimum possible. Wearing a mask, following social distancing measures is still a must. Ensuring adequate ventilation and air exchange in closed, crowded spaces is imperative. Getting jabbed will save people from severe complications and even hospitalisation. Our lives may be different from what we had before the pandemic, but we need to make sure we do everything to curb the spread of the virus.