Who should be vaccinated next?

A new battle in the Second wave: Vaccines vs. lockdowns

In the March of 2021, the optimistic sentiment about COVID-19 in India changed. The trend in infections started to look similar to that in 2020, but worse. The number of daily new cases far exceeds the daily new cases from the first wave. States like Maharashtra have witnessed around 5 times more daily cases than in the first wave, while as a national average it is 2 times more. In 2020, the COVID-19 infections and deaths could be reduced by stringent measures and lockdowns. The consequence was a battered economy. The rise of the second-wave is accompanied by the rising fears of lockdowns and their consequences. The silver lining is that now vaccines are available, giving room for a cautious optimism.

India has authorized use of two vaccines COVISHIELD (made by Serum Institute of India) and COVAXIN (made by Bharat Biotech Intl. Ltd.). Some of the questions asked before approving a vaccine are if it is safe and if it reduces chances of infection, reduces the transmission to others, reduces the chances of acute infections needing hospitalization and reduces the chances of death. Since the answer is affirmative to all these questions, the question is if the second wave can be managed effectively by vaccinating rapidly. The mass-vaccination will reduce the burden on the hospitals, deaths due to COVID-19, all with a reduced need for a complete-lockdown.

The rapid rise of infections suggests the next 100 days in the second wave may be very crucial in deciding India’s long-term recovery path and extent of manpower and economic loss would crucially depend on the speed we achieve minimal viable and in some sense optimal vaccine coverage. Logically it appears that the priority should be to immediately vaccinate everyone.

Immediate is not practical: Supply is large but finite

India is one of the largest producers of COVID-19 vaccines in the world. Approximately 50 Million COVISHIELD and 5 Million COVAXIN vaccines are produced per month. While their manufacturers claim that they can increase the production manyfold, it seems evident that neither one can increase the production substantially in the next 100 days. This is largely due to the fact that there are several steps involved, from setting up the plants to ensuring complex biosafety protocols such as BSL3. Various news articles over the last few months suggest that at the beginning of April India has a stockpile of around 100 to 150 M vaccines. Here, we also remind that COVISHIELD has a huge export commitment which can be delayed at best by a few months. Keeping all this in mind, it is safe to say that in the next 100 days, India has a stockpile of 150 to 250 M doses. So, one can assume that India would be able to administer around 3 M doses for the next 50 days or so and then it would slow down in a range of 2 M per day after that until new production facilities become operational.

Universal vaccination. The scale of it.

First the success story. India is one of the only few countries which has managed 114 M vaccinations in a short time period. Yet the vaccinated are a small fraction of the Indian population of 1400 M (estimated for year 2021). As 50% of Indian population is below 25, which need not be vaccinated, for the purpose of vaccination Indian population is effectively 700 M only. It is typically expected that 75% of the population needs to be vaccinated to reach the level of vaccine assisted herd immunity. Thus, approximately 500 M people are needed to be vaccinated before herd immunity can be achieved. As everyone needed to be given two doses, such a program would require availability of 1000 M doses. This is a huge task and at a sustained rate of 3.33 M per day such a program would take 300 days.

Interestingly, COVID-19 rates have declined in the four countries where 40% of the population was vaccinated. Even expecting the same to happen in India, it would take 120 days to achieve even that inflection point at the current rate of vaccination. Considering the weak Indian health infrastructure, which is already being overwhelmed, it is evident that we cannot take risk of untamed progression of the disease for next 100 days or so. It is obvious that such a route would be disastrous for the economy and might lead to considerable loss of life. Although everyone has a right to the vaccine, from the point of view of risk to life, some need it more urgently than others.

How is the vaccination thus far? Percentages, Priorities

The percentage of the population vaccinated need not be the most important metric to track. Age and presence of comorbidities places some at a higher risk of death. Based on census data of 2011, one can estimate that around 116 M of Indians are over 60 years of age and 250 M are in the age bracket of 40 to 60. These age groups may be the most affected by COVID 19 as the chance of mortality is extremely high among the senior citizens over 60 years of age, followed by those in the 40-60 age group. Thus, it is not surprising that the government of India has decided to vaccinate these two age groups one after another. In fact, to account for the shortage of vaccines, the age group is restricted to 45 plus only. We also have another 340 M people in the 25-40 age group for which vaccination is yet to start but very much needed. Approximately around 18% of people in the range of 40 to 60 are vaccinated already. This should ensure that damage from the second wave would not be as life threatening (relatively speaking) as the first wave was. By 15 April, India has already vaccinated around 38% of people who are above 60 at least once. However, there are very large differences in the percentage of vaccination across the states (shown in the graphic): ranging from 2% in Manipur to 93% in Sikkim.

Sharing the responsibility. Tell me again, what does a vaccine do?

A vaccine is expected to train the immune system weeks before the actual exposure to the real infection. The result is the immune system is ready to fight. Without going into the biology of it, based on the data from Oxford-AstraZeneca, COVISHIELD is expected to reduce the chance of contracting infection by 67%. It is also expected to reduce the chance that a vaccinated person spreads the infection to others by 70%. Thus, a vaccinated person is not only protecting themselves but also others. Estimates show that the Pfizer COVID-19 vaccine reduces mortality by 80%. Similar results may be expected also from COVISHIELD and COVAXIN.

Individual responsibility. Hidden risks at Home.

To be vaccinated is every person’s right, and in a sense also a responsibility. Since it reduces the chance that the person contracts infection, and spreads it. “Home” is a place where one should feel safe. However, since masks, social distancing are not possible at home. Thus, in the times of COVID-19, a home is also a place where most transmissions happen. This ‘secondary attack rate’ is the highest at home, and it is about 30%. Thus, a person who is eligible for a vaccination, and receives it, is protecting themselves and their family. Especially, if the family has a Senior person at home, the compounded effect of the younger and the Senior person receiving vaccination are enormous (graphic below). The older person may or may not be in a position to take the vaccine, because of their immunity levels. Thus among the eligible persons, those who have a vulnerable person at home should understand how the many reductions: 67% reduction in infection, 70% reduction in transmission, and 80% reduction in chance of death compound to reduce the number of overall infections and deaths. The eligible, especially with senior citizens and vulnerable should immediately be vaccinated to protect themselves and their family.

Government strategy. Who’s next in the rolldown of priorities?

When an old person is vaccinated once, his/her mortality risk is almost halved. However, it is still quite high in contrast to a typical young person. Thus, it is not surprising that attention so far was on seniors. However, even after vaccination a senior is at considerable risk and in order to protect them ideally one needs to vaccinate their close contact group. One need to ask is this a finite set or effectively mean universal vaccination. Fortunately, in the Indian context family plays a central role in contact dynamics of a senior citizen. Most often a senior is either interacting with family people. For many upper middle class seniors in an urban setting this could be interaction with their maid, driver etc. While for the poor and lower middle class this might involve interaction with their employer. On an average, we would expect that an adult living in a multigenerational home is at considerable risk due to mobility of young in the family. An effective strategy would be to cut this chain by vaccination of the young people who are mobile and are in close contact with old people. Considering typical family structure in an Indian household one may expect that size of this cohort to be on an average comparable to the old population itself. As the size of the old population is around 116 M, one would expect that we are talking about vaccination of another 100 M people on priority basis. While the universal vaccination goal is still far, universal vaccination of the vulnerable and the first contact of the vulnerable may be a rapidly achievable goal. This may imply prioritizing people even much younger than the current priority group of 45 years age. For example, a 35 year old living with a grandparent of 85 years at home, even if the latter is already vaccinated, qualifies more than a 45 year old in a nuclear family based on their effective risk. It may also be practically possible to implement this, by allowing one extra person on Aadhar of every senior citizen. One would expect that a significant portion of this population can be vaccinated in the next 100 days. This would also bring in a flavor of crowd wisdom where families will themself choose the most vulnerable in the family.



Views expressed above are the author’s own.


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