Hyderabad-based Biological E’s Corbevax and SII’s Covovax, both of which are protein-based vaccines, are India’s best bet for a booster shot
India is yet to take a call about administering a booster dose of the novel coronavirus disease (COVID-19) vaccine. But if a decision is arrived upon, it must be vaccines that are based on a different platform than the first two doses.
However, not only does this debate raise clinical concerns — about efficacy — but also ethical ones. Several developed nations are now administering booster doses in the face of rising omicron cases. Others though are still struggling to vaccinate their population with the first two.
Africa has, till now, fully vaccinated just eight per cent of its total population. In comparison, Europe and North America have fully vaccinated 59 per cent and 56 per cent of their populations respectively.
Meanwhile, India falls somewhere in between, at just 37 per cent people who have received two doses of the COVID-19 vaccine.
“Giving boosters at this time in a country like India, is really putting the cart before the horse,” Shahid Jameel, a virologist and former head of the Indian SARS-CoV-2 Genomics Consortium (INSACOG) told Down To Earth.
He further argued that by saying you should allow boosters means that you are taking those doses away from people who only have one dose or none.
Our priority should be to get the second dose to people who already have one dose and to get two doses to people who have no doses. “But that doesn’t mean we should not talk about boosters,” he added.
Data worldwide shows that you get protection from disease with two doses of the COVID-19 vaccine doses. “If our benchmark is going to be protection from symptomatic infection, then I think we are going to be continuously chasing this,” Jameel said.
So what are India’s options?
There are, at present, four approved vaccines in India — Covishield (90 per cent in circulation), Covaxin, Sputnik V and Zydus Cadila.
In August 2021, the Union health ministry told the Lok Sabha that monthly production of Covishield will increase from 11 crore to 12 crore doses and that of Covaxin from 2.5 crore to 5.8 crore doses.
However, Serum Institute of India’s (SII) CEO Adar Poonawalla last week said production will be halved owing to a drop in demand.
Somebody who got two doses of Covishield will not benefit very much from a third dose of Covishield, owing to the nature of the vaccine. The same goes for Sputnik V.
Jameel explained this:
(Covishield) is made using a virus that causes common cold in chimpanzees, which is used to make the COVID-19 virus spike protein. So when you have given two doses of Covishield, you are not just raising immune response to the spike protein, you are also raising immune response to all the chimp proteins in the vehicle virus which are greater in number. So if you keep on giving that vaccine, you are preferentially boosting responses to the chimp virus proteins and not the spike protein.
The Sputnik V vaccine also uses a similar virus.
Giving Zydus Cadila’s ZyCov-D as a booster dose, may work clinically. But it is not a feasible option simply because of capacity limitations. Another option is the mRNA vaccine, such as Pfizer and Moderna. However, these have not yet been authorised for use in India.
Hyderabad-based Biological E’s Corbevax and SII’s Covovax — both of which are protein-based vaccines — are India’s best bet for a booster shot.
Protein vaccines can be produced in very large amounts and are perfect for booster doses. In people who got Covishield, for instance, a protein vaccine will selectively boost just the spike response.
“Between the two companies, they can make about 1.5 to 2 billion doses annually. Phase three trials have been done for both vaccines, the data is with the regulator. Let us approve them, then we will have plenty of vaccines to give as boosters and also to maybe give as primary immunisations,” Jameel said.
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