The problems with one-shot Covishield

NDTV quoted unnamed sources in the Indian government saying it will be conducting a study to assess the feasibility of deploying the Covishield vaccine in a single-dose regimen instead of continuing the extant double-dose regimen.

At any other time, such a statement may have been sufficient to believe the government would organise and conduct a well-designed trial, publicise the findings and revise policy (or not) to stay in line with the findings, informed by socio-economic considerations. But the last 15 months have thrown up enough incidents of public-health malpractice on the state’s part to make such hope outright stupid. I’m fairly certain, especially if the vaccine shortage persists and the outbreaks on an upward trajectory in some parts of the country at the moment aren’t tamped down quickly, that the government is going to conduct a trial, not publish its methods and findings and push through a policy to deploy Covishield as a single-dose shot.

Of course I would be happy to be proven wrong – but in the event that I’m not, I’m already filled with a mix of sadness and fury. The government seems set on finding new ways to play with our lives.

News that the government is going to conduct a feasibility study broke to the accompaniment of a suggestion, by NDTV’s same unnamed sources, that Covishield was originally intended as a single-dose vaccine and that it was later found to be better as a two-dose vaccine. This is ridiculous to begin with, considering Covishield’s phase 3 trials around the world, conducted by AstraZeneca and the University of Oxford, tested the two-dose regimen.

But it is rendered more ridiculous because Public Health England (PHE) reported just a week ago that two doses of Covishield are necessary for a recipient to be sufficiently protected against infections by the B.1.617.2 variant. The PHE study found that one dose of Covishield had an efficacy of 33% against symptomatic COVID-19 caused by the variant, increasing to 60% after both doses. Has the Indian government forgotten that B.1.617.2 is becoming the more common variant circulating in the country? Or is laundering the national party’s image more important than the safety of hundreds of millions? (The latter is entirely plausible: in the last seven years, the country has seldom been larger than the supreme leader’s ego.)

The PHE study isn’t without its shortcomings – but I’d be more inclined to pay attention to them at this moment if:

  1. I didn’t have to contend with the non-trivial possibility that the Indian government will bury, obfuscate and/or twist the data arising from its assessment, and therefore we (the public) need to bank on whatever else is available;
  2. I didn’t have to contend with the fact that data from Covaxin’s phase 3 trial (which apparently went past its final interim-analysis endpoint in April) and Covishield’s bridging trial (which IIRC concluded on March 24) are still missing from the public domain;
  3. If we could access large-scale effectiveness data of the two vaccines (the National Institute of Epidemiology, Chennai, is set to begin collecting such data this week); and
  4. If there was any other reliable data at the moment about the two vaccines vis-à-vis the different variants circulating in India.

There is another problem. If Covishield is administered as a single-dose vaccine, its efficacy against symptomatic COVID-19 caused by B.1.617.2 viral particles is 33% – which is below the WHO’s recommended efficacy threshold of 50% for these vaccines. If the Indian government formalises the ‘Covishield will be one dose’ policy and if the B.1.617.2 variant continues its conquest, will the vaccine, as it is used in India, lose its place on the WHO’s vaccine list? And what of the consequences that will follow, including other countries becoming reluctant to admit Indians who received one dose of Covishield and one dose of the BJP’s way of doing things?

I would be wary, too. The longer the particles of the novel coronavirus are able to circulate within a population, the more opportunities they will have to mutate, and the more mutations they will accumulate. So any population that allows the virus to persist for longer automatically increases the chance of engendering potentially deadlier variants within its borders. One-dose Covishield plus B.1.617.2, and other variants, will set just such a stage – compounded by the fact that Serum Institute, which makes Covishield, has a much larger production capacity than Bharat Biotech, the maker of Covaxin.

(The PHE study also found that Covishield and the Pfizer-BioNTech vaccine had an efficacy of “around 50%” against symptomatic COVID-19 caused by an infection of the B.1.1.7 variant.)

In fact, the government could have made more sense today by saying it would prioritise the delivery of the first dose to as many people as possible before helping people get the second one. This way the policy would be in line with the most recent scientific findings, be synonymous with a single-dose campaign and keep the door open to vaccinating people with both doses in a longer span of time (instead of closing that door entirely), while admitting that the vaccine shortage is real and crippling – something most of us know anyway. But no; Vishwaguru first.