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It’s never safe to let our guard down any time over Omicron, says expert

Shoppers gather at Sarojini Nagar market after lifting of odd-even formula by Delhi government, in New Delhi on January 28, 2022.

Shoppers gather at Sarojini Nagar market after lifting of odd-even formula by Delhi government, in New Delhi on January 28, 2022.

“Even though Omicron doesn’t seem to be as virulent as Delta, it’s never safe to let our guard down any time,” warns Giridhar R Babu, professor and head – Life Course Epidemiology, Public Health Foundation of India, in an interview. He says that as long as there is high circulation in any part of the world, there is scope for developing new variants, including the possibility of a more virulent strain.

Is it the right time to let our guard down, as Omicron doesn’t seem to be as virulent as Delta ?

Absolutely not. It is never safe to let our guard down any time, especially when the proportion of least protected and those at high risk is higher. The overall threat posed by Omicron largely depends on several factors. These include transmissibility, the extent of spread across the population and how well the vaccines or prior infection with a wild variant (any variant of SARS-CoV-2) offer protection. Also, this is not the last variant we will see.

 

So long as there is high circulation in any part of the world, there is a scope for developing new variants, including the possibility of a higher virulent strain. From what we know so far, Omicron spreads faster than the Delta variant. However, Omicron can in no way be dismissed as a mild, severe and moderate disease that affect vulnerable persons, and the hospitalisations can keep continuing with a lag time from the peak in cases.

Only data-led decisions can aid in reviewing policy and implementation for proactive management of healthcare capacity, including ICU beds, oxygen availability, adequate health care staff and surge capacity at all levels.

Should we encourage 100% opening of establishments and markets?

The principles of enforcing any restrictions of disease control need to depend on background prevalence and overall impact on society compared to the counterfactual scenarios (of not imposing restrictions). With Omicron spread, the goal should be to minimise hospitalisation to prevent or contain crowd formation and super-spreader events. Ideally, it might be best to let the establishments and markets continue functioning without a blanket ban, but with necessary precautions.

Enforcing adherence to COVID-appropriate behaviour and allowing only persons with complete vaccination history to assemble in gatherings can be helpful. Strong surveillance, including scaling up the testing in all areas uniformly to detect the persons with symptoms, is essential. The local markets need to be regulated for implementing the necessary and mandatory precautions.

What about educational institutions considering the fact that Omicron hit children more this time and a large population in this cohort is still unvaccinated?

Transmission of SARS-CoV-2 in schools depends on the local transmission rates; the types of variants circulating; the epidemiology of COVID-19 among children, adolescents, and staff; vaccine coverage for those eligible; and mitigation measures in place to prevent transmission. I think it is time to improve the vaccination coverage of the eligible children and, at the same time, open schools with enhanced measures to prevent and detect transmission in the event of outbreaks in schools.

In unvaccinated children, it is important to surround them with vaccinated individuals (parents, school staff, drivers of school buses etc.). Evidence regarding the safety and efficacy of vaccine must decide the next course of action in other age groups of children.

Also, the long-term effects after COVID-19 infection are unknown, including in children. Hence, evidence-based action is needed to assess the need and roll out the vaccines in younger children.

Does the opening up push the virus to mutate further and, as we cannot control the outcome, how dangerous is this?

For RNA viruses, constant changes and some leading to mutations are a routine aspect of the evolution. Without understanding the specific evolutionary mechanisms, predicting how virulence might emerge is imprudent and challenging. The presence of mutations does not always imply the presence of something unusual or dangerous. Instead, they can assist us in understanding how the virus is changing, providing us with inputs on how to prevent impending epidemics.

High circulation and a higher proportion of unvaccinated persons are threats to the development of newer variants, not opening up restrictions. Opening up will lead to more infections, at least for a transient time, as more vulnerable people are exposed. However, there is no evidence that opening up restrictions is related to the development of dangerous variants.

What is your opinion on mix and match precaution dose?

The results from the ongoing studies in India can provide inputs on whether mixing vaccines available in India is safe and effective (compared to only two doses or compared to previous infections). Studies from elsewhere show that mixing vaccines of different platforms can result in higher IgG and neutralising antibodies and more strong cellular immune response. (Oxford–AstraZeneca and the Pfizer–BioNTech COVID-19 vaccines produce potent immune response against SARS-CoV-2.) In addition to enhancing vaccine effectiveness, the evidence from these studies indicates that mix and match can also help resolve the shortage of vaccines.

Should the country look at re-vaccinating its entire eligible population?

It is more important to complete the primary vaccination of people than re-vaccinating those who are already vaccinated. Hence, we need to establish if the eligible population for booster is same as eligible population for receiving primary doses.

In participants older than 50 years of age, the available evidence from other studies shows that booster dose (with mRNA) can reduce mortality significantly (compared to those who did not receive). While the vaccine should be made available to all the elderly and those with comorbidities, we need to examine the data in India and the additional advantage of booster dose in all the other age groups.


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Printable version | May 21, 2022 11:31:45 pm | https://www.thehindu.com/news/national/its-never-safe-to-let-our-guard-down-any-time-over-omicron-says-expert/article38338623.ece