Switching Tactics: Why India Must Temporarily Prioritise First Doses Mid-Wave

India is currently in the midst of a major wave in Covid-19 cases driven by the ‘double mutant’ B.1.618 strain, data for which was submitted to GISAID. Data from covid19india.org shows that the wave is slowing, but the peak is likely potentially a few weeks away.

While active cases in Maharashtra and Chattisgarh, the states with the majority of cases early on, have started to peak, but others like West Bengal, Punjab, Karnataka and a few others continue to show active case growth.

Stopping the wave is the highest priority of the government. This article makes two recommendations that can immediately make a difference:

1. Immediately pause 2nd dose administrations for a period of one to three weeks, pivot to first dose administrations.

2. In high risk clusters, enable everyone to receive a first dose right away, not starting in May.

Rationale

Our approach so far has been tailored to a situation where conditions were manageable and the vaccination process could be done in a planned two-dose manner. This was fine from January to March.

Right now we’re in the middle of a wave that has not peaked. Hospitals are filling up, people are dying and case counts keep rising. High-impact, immediately executable actions matter. Case in point:

By the third week of March, 60 per cent of Israel’s population had at least one Covid-19 vaccination. Even before that - in mid March - Israel reported massive drops in test positivity rate (TPR) and transmissions, despite being weeks away from fully vaccinating its small population of 9 million, which is about that of Bengaluru.

Both Israel and the UK, which have high vaccination coverage of their population, reported significant drops in transmission and TPR numbers as they hit the point of 40-50 per cent of population having received at least one shot.

According to multiple studies published in the Lancet (see link1 and link2) in early March 2021, AZD1222 (Covishield) was recommended at a 12-week dosage interval. India increased its interval recommendation to 7 weeks on March 22.

In effect, the recommendations of this article amount to aligning with the wider interval. Multiple countries — UK and Trinidad for example — use Covishield with a 12-week dosage interval today.

This data shows that at least with Covishield, there is medically supportable basis for extending the second dose interval. Covishield accounts for over 90 per cent of the 118 million first doses so far.

Calculations show the impact of extending Covishield second dose interval to 9 weeks:

Thus, extending the dosage interval to 9 weeks puts the second dose requirement back three weeks and frees up nearly 41 million doses for first dose utilization during that time frame — all from the currently available supply.

The Indian Situation: Pivoting to Maximising First Doses

Let us look at where India is today. India has around 320 million people aged 45 and over, who constitute the high-risk population being vaccinated. As of today, 117 million (36 per cent) of them have received at least one dose of vaccine. At the main onset of this wave at the start of April only 58 million had received at least one dose.

This is a very good progress so far, but it brings with it a major risk - starting May, millions who received first doses four-six weeks ago become eligible for a second dose.

This can be termed the second dose crowding out effect. It can be explained simply: our daily total vaccine doses are around 2.5-4 million doses, up from 1.5 million a day in March. Calculations indicate that by mid May, 80 per cent of currently available daily doses will be 2nd dose, based on current priority.

This means that the number of people with at least one vaccination will increase to 130 million by end of April. If we immediately stall second doses, we’ll have 135 million people with at least one dose by end of April by maintaining the current rate of vaccination.

However, the numbers will stall there, rising to only 142 million by mid May, since most doses will be consumed by second dose requirements.

This is a problem in the middle of a wave. As the Israeli data shows, we need the most number of high risk people with at least one dose as we can achieve. Each vaccinated person is far less capable of spreading further. If they get Covid, they’ll almost certainly recover quickly, as many celebrities who recently had their first doses and got Covid did.

What happens if India completely suspends 2nd dose administrations for up to three weeks and only vaccinates people needing first doses ? How about if we receive - let’s say 20 million doses of - Sputnik V and also use them for first doses. Here are the projections:

In other words, we can rapidly increase at least a one-dose coverage of our high risk population past 50 per cent within three weeks if we pause second dose administrations. It could reach 60 per cent if additional vaccines are available.

Focusing On Clusters

A temporary focus on only first doses can make an enormous difference in transmission rate, especially if vaccinations target clusters. The CoWin registration setup lets the government focus on targeting vaccines to the most high-prevalence districts, where it can further accelerate mitigation efforts by opening eligibility to all.

Covid-19 is lethal because it spreads rapidly, and in a very short time generates too many patients who simultaneously need care. Those who might normally be saved end up perishing because there were no resources in the middle of a wave.

However, by a single vaccination, not only is the risk of severe illness with need for hospitalisation completely eliminated , but those who get Covid - the vaccine does not prevent it but just drastically improves outcomes - become very poor transmitters.

While long term immunogenic response research is ongoing, early data indicates that vaccines result in enough antibody generation within days that people who get Covid soon after; Yogi Adityanath got vaccinated on 5 April and tested positive on 14th, indicating infection days before.

Recently released data from ICMR indicates extremely low ‘breakthrough’ case rates even after first dose - on par with those who have two doses:

Both Covaxin and Covishield have near identical - and negligible - risk of positive results after both one and two doses. This suggests that under current real world conditions, both vaccines are generating strong immunogenic responses in the Indian population to the currently prevalent variants.

Given the nature of the current situation, a pivot to maximising first doses is critically helpful, especially combined with vaccination of all people in concentrated case clusters. Within days of such targeted actions, it would be possible to see the result of a significant number of transmission chain links broken, causing the wave to abate far quicker than otherwise.

Once it abates, the government can resume regular prioritisation of second doses.

Crucially, none of the recommendations here take time to execute. Production does not need to scale up. We don’t have to wait until late summer when wide swathes of the population will have been immunized.

In the middle of the current crisis, there are few low-risk, high-reward actions with potentially immediate gains, and these recommendations are worth considering.