1977 was the year when smallpox was eradicated from the world. India was one of the last places where the disease was prevalent, and researchers used a strategy called ring vaccination to contain it. The idea of ring vaccination was simple. Authorities would identify the infected person, monitor the ring of people around the infected entity and vaccinate them. Then the second ring of people who came in contact with the first ring was identified and vaccinated. The World Health Organisation replicated these efforts during the Ebola outbreak. Contact tracing during Covid-19 is done similarly.
But as Covid-19 vaccines are available now, many are asking if a ring vaccination strategy can be followed in the case of Covid-19. While there is certainly a need for mass vaccination, Dr K Srinath Reddy claims that ring vaccination may not be a viable approach in the case of Covid-19.
“Ring vaccination is a concept where you have a contagious disease which spreads from person to person. If you vaccinate the people around and they become immune and you can limit the transition of the virus. When there is an aerosol spread, it is less effective. In the case of Covid-19, a vaccine’s primary purpose is to prevent severe disease. The effect on limiting transmission is also going to be there, but that is more of a delayed effect with a large number of people getting vaccinated,” he said.
However, Dr Reddy believes that the government can target specific areas for vaccination first.
“It is important to have more vaccines in areas where cases are rising more rapidly,” he told Business Standard.
Evidence indicates a wide disparity in the spread of the virus across the country. So, the government can prioritise one zone over the other. Urban districts account for two-thirds of the total infections across the country. Within these urban centres, the top six metropolises have a 68 per cent share. Delhi, Mumbai, Kolkata, Chennai, Bengaluru and Pune comprise nearly 43 per cent of the total cases and deaths in the country.
While the first priority is to vaccinate those above the age of 45, even this can be ramped up in areas where the population is more susceptible, and the number of cases is higher. So, for instance, Maharashtra can redirect vaccines to zones where cases and deaths are rising, and the population is over the age of 45 and then cover other districts.
Another strategy could be to reclassify red, orange, and green districts based on the severity of infections and growth rate and then provide vaccines in priority areas. The government can reach districts that are red and have more people over the age of 45 first and then focus on other red districts.
An analysis of district-level data shows that there are 445 districts with a higher case growth rate than the national average. Cases in most of these areas are doubling in less than a month. A BS analysis correlating data of high case growth districts with level of vaccination finds that less than 13 per cent of people in these areas have received the vaccination, whereas, in districts with a lower growth rate of cases, the vaccination rate is 14 per cent.
However, analysing the growth rate of cases alone may not be a prudent strategy as some of the largest cities, like Mumbai, Delhi, have witnessed a fall in the growth rate of cases over the last two weeks.
In such a scenario, we can also differentiate the data using the growth rate of deaths. There are 355 districts across the country where deaths are higher than the national average.
Another measure that state governments need to consider is vaccination outside metropolises. In the case of Maharashtra, for instance, while there are 13 districts with the growth rate of infections higher than the national average, only Mumbai, Pune, Nagpur, Bhandara and Kohlapur have been able to administer more than 20 doses per 100 people. The rate of vaccination for the rest of the state is 11 per cent.
Similarly, in Karnataka, Bengaluru, Mysuru and Udupi, are the only three districts to have administered over 20 doses per 100 people; the rest of the districts average 14 per cent.
There is a need to pick up vaccination in other areas of concerns as well.