India Will Need 170 Million Lesser Doses If It Conducts Antibody Testing Before Vaccine Inoculation

Sep 25, 2020

India Will Need 170 Million Lesser Doses If It Conducts Antibody Testing Before Vaccine Inoculation

At CIO, we strongly believe that at least 2 or 3 of the vaccines that are currently under late-stage trials will be approved and rolled out by the end of 2020 (see the top vaccines under phase-3 trials). The next question that arises after vaccine approval is who will be vaccinated first and how many doses of vaccine will India need initially? We did an analysis to estimate this:


  • At least one vaccine will be approved and rolled out by the end of November 2020.
  • People above 50 years of age will be vaccinated first. (keeping in mind that the severity rate is higher in this age group)
  • Healthcare workers will also receive the vaccine first.
  • Those who have already had COVID-19 will not be vaccinated. (because there isn’t much reliable data on the possibility of reinfection, or how the immune system will react when a vaccine is administered to a previously infected person).
  • India has not peaked and does not peak before December as the weather turns colder and the virus gains strength.

Need 524M doses if you go by official stats

On Sep 21, India recorded a total of 5,562,711 cases. We estimated that the official confirmed COVID-19 cases by the end of November would be 32 million cases, with a nation’s doubling rate of 28 days. 

According to the age-wise distribution of cases in Karnataka and Maharashtra, 33% of COVID infections are seen in people above 50 years of age. Considering the same for India, by the end of November, with a total of 32 million confirmed COVID cases, we estimated that 10.5 million infected people (33% of 32 million) will be above 50 years.

According to the ICMR, 1073 healthcare workers were infected with COVID as of early May. We estimated that the number of healthcare workers infected with COVID by the end of November would be around 2.75 lakh (5% of total HCWs) with the same nation’s doubling rate.

India’s population of people above 50 years of age is 267,742,000. The total number of healthcare workers in India as of 2017 is estimated at 5.49 million. With 10.5 million people above 50 years and 2.75 lakh healthcare workers infected already, India would need 524 million (2 doses per individual = 2×262 million) doses of vaccine initially to vaccinate health care workers and people above 50 years of age who haven’t been infected.

How India cuts its requirement by 170M doses

But, India can reduce its requirement by an estimated 173 million doses by antibody testing prior to vaccination. Here’s why:

Studies are suggesting that the number of people who have been infected already is much higher than the officially recorded cases.

  • According to the report of the first national serosurvey conducted by the ICMR, India had likely 6.4 million COVID cases in early May whereas the actual cases reported were 66, 123 as on May 10. The cases were 97 times higher than the actually reported ones. This report suggests that a large number of cases could have gone undetected as testing was allowed only to symptomatic people and asymptomatic people who were in direct contact with a laboratory-confirmed case (see ICMR guidelines March 20).
  • CIO’S own survey (yet unpublished ) suggests that hundreds of cases existed in February itself, and cases were over 100x of official statistics.
  • T. Jacob John, a former director of the ICMR’s Center for Advanced Research, estimated that India had potentially 40 million cases around Sep 10. But the actual cases recorded on September 10 were 4,562,606. The estimate was almost 9 times higher than the officially reported ones.

From the above data-points, a story emerges.  Since the early days, India was unable to find and test cases but has likely improved with time.  Now, using the latest, lowest estimate, we calculate the number of people exposed to the virus. If the estimated cases are almost 9 times higher than the actual ones, then by the end of November 2020, around 288 million people – (9 x 32 million) will have already been exposed. Among them will be,

  • 95 million (33% of 288 million) people of above 50 years
  • Around 2.5 million HCWs (45% of total HCWs). Alternatively, another data point suggests around 2.4 million HCWs (0.83% of total COVID cases, 288M – based on ICMR data in early May). For the analysis, we consider 2.5M HCWs to be exposed already.

As a result, about 176 million people will need initial vaccination based on our analysis. India would then need only 352 million doses (2 per individual) of vaccine initially, which is about 172 million doses less than what would be needed if we did not test for antibodies.


If India makes antibody testing a requirement for inoculation, to find out the people who have already been exposed to the virus, then it will likely require over 170 million less doses of vaccine. This is because 85 million people will be given lower priority as they already have antibodies in them, and also we don’t have enough data on reinfection.

Limitations of the analysis:

Most of the estimated unreported cases could be biased towards the younger age groups. However, we are comfortable with our analysis for the following reasons.

  • We have taken the lowest multiplier (9 times) for the estimate. There are other data points suggesting the cases could be actually 97 to 100 times higher.
  • 40% of cases are asymptomatic, most of them are less likely to be reported.

Therefore, 352 million doses would still be indicative of the potential number of vaccine doses needed.

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