Dear government, the time to give Covid vaccine booster dose is now – The Economic Times

Clipped from: https://economictimes.indiatimes.com/opinion/et-commentary/dear-government-the-time-to-give-covid-vaccine-booster-dose-is-now/articleshow/88398425.cmsSynopsis

Despite an impressive rollout, India still lags in vaccinating its population. About 1 billion Indians are 18 years or older, and currently the target of Covid-19 vaccination. By Sunday, 829 million received one vaccine dose and 549 million received two doses. This computes to 28% and 17% adults having received either only one dose or none, respectively.

Shahid Jameel

Shahid Jameel

Virologist, and fellow, Green Templeton College, University of Oxford, Britain, and visiting professor, Ashoka University, HaryanaSince its emergence in late November, the Covid-19 virus Omicron variant has spread to 89 countries, with cases doubling at a rate of 1.5-3 days. India had 147 confirmed cases by Sunday, and though these numbers are still small, cases are doubling every three days. These are likely to add up quickly in the coming days.

At a press briefing on Friday, V K Paul, head of the National Covid-19 Task Force, suggested that India may touch 1.4 million daily cases if it experiences a Europe-like Omicron wave. According to IIT Kanpur’s SUTRA (Susceptible, Undetected, Tested (positive), and Removed Approach) model, the most optimistic estimate is a peak around late February with about 100,000 daily cases. The worst-case scenario is a peak in late January with about 150,000 daily cases. Either way, India is looking at a third wave.

Vaccines have been critical in restricting severe disease and mortality from Covid-19. However, since virus-neutralising antibody levels wane with time, protection from symptomatic infection is expected to follow suit. Omicron has accumulated many mutations in its spike protein – which forms a large structure known as a spike or peplomer projecting from the surface of an enveloped virus – including several in the key receptor-binding domain.

As a result, early studies have shown 6- to 40-fold reduction in antibody neutralisation for Omicron compared to the original virus used for vaccine development. Other studies show that Omicron transmits 3-fold better than the currently dominant Delta variant and can cause five times more breakthrough infections.

A modelling study (bit.ly/3GZQqGc) released on Thursday by the Imperial College, London, estimated vaccine efficacy to be substantially impacted by the Omicron variant. Six months after the second dose of theAstraZenecaNSE -2.22 % vaccine, its efficacy against mild disease dropped to only 19% against Delta and 3% against Omicron. Efficacy increased following aPfizerNSE -3.16 % vaccine booster dose. After two months, it was pegged at 81% against Delta and 39% against Omicron.

According to this model, without a booster efficacy of the AstraZeneca vaccine against Omicron-induced severe disease and death was estimated to be 18% and 29%, respectively. Since this analysis is based only on neutralising antibody data, it is likely to be a worst-case scenario. Vaccination and prior infection also generate T-cells that protect from severe disease, as well as antibody and T-cell memory that is recalled rapidly on future infection. Booster vaccination augments this further.

Take an Adult Decision
Despite an impressive rollout, India still lags in vaccinating its population. About 1 billion Indians are 18 years or older, and currently the target of Covid-19 vaccination. By Sunday, 829 million received one vaccine dose and 549 million received two doses. This computes to 28% and 17% adults having received either only one dose or none, respectively.

India needs about 620 million additional doses to complete two-dose vaccination of adults. At the present rate, this equals 560 million doses of Covishield plus 60 million doses of Covaxin. With this backdrop, news of Serum Institute of India (SII) planning to cut Covishield production by half, and no increase in Covaxin production, is of concern.

What vaccines can be used as boosters? The World Health Organisation (WHO) has now given Emergency Use Approval (EUA) to nine Covid-19 vaccines – two RNA (Pfizer, Moderna), three viral-vector (Johnson & Johnson, AstraZeneca and Covishield), three inactivated whole virus (Covaxin, Sinopharm, Sinovac) and one protein subunit (Covovax). A Phase 2 study (bit.ly/32cYchh) from the University of Southampton, Britain, published in the Lancet in December, compared seven different vaccines as boosters in people who had earlier received two doses of either the AstraZeneca (AZ) or the Pfizer (PF) vaccine.

The best combinations were PF/RNA > AZ/RNA > PF/AZ > RNA/Protein > AZ/Protein. Inactivated viral vaccines boosted poorly, and so did an AZ boost in people who already got two doses of it. Accordingly, countries such as Britain and the US have used the two RNA vaccines for boosters. But this doesn’t offer many options to India, which has used only the AZ (Covishield) and inactivated (Covaxin) vaccines and has no access to RNA vaccines.

What should be the path for India? It was reported in June this year that SII can make 200 million doses of Covovax available by December 2021. Though this vaccine has received WHO approval, it is still pending from the Indian regulator. That must be fast-tracked, and so should approval for another protein vaccine – Corbevax-E, produced by Hyderabad-based Biological E. Since 90% of vaccinated Indians have received Covishield, using protein vaccines as boosters presently offers the best option for India.

To Live, Get Shot
Should India vaccinate all adults with two doses before it rolls out boosters? The Imperial College study offers clues. For countries such as India that have experienced high levels of prior infections but still have a substantial fraction of unvaccinated adults, there would be greater public health impact if boosters are given to the elderly and high-risk population. That is predicted to reduce mortality by an additional 5%, compared to using the same doses for immunising younger people to reduce transmission.

India’s ministry of health and the National Expert Group on Vaccine Administration for Covid-19 (NEGVAC) await results from local booster trials, which are yet to start, to formulate a national policy on boosters. Why can’t global data guide us? One painful lesson over the past year is that Indians are not special, but just as susceptible as people elsewhere. The time to act is now.

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