Covid waves getting smaller in India; US, France show a similar trajectory

On February 20, India recorded less than 20,000 infections for the second day in a row (the average for the latest week was 24,713). A month ago, India had hit a peak of 347,254 cases.

Although infections were high during the current wave, the case fatality rate (number of deaths as a proportion of the total number of cases) has remained low. A Business Standard analysis shows that the third wave has been considerably smaller than the first and second waves, both in terms of deaths and the number of cases.

Furthermore, the trend repeats itself not just in India but in other countries as well.

Data analysis of the three waves shows that, in terms of cases, while the first wave of infections, starting in March 2020, lasted 249 days until infections dipped, the second wave of disease owing to the Delta variant continued for 189 days. The current wave, led by the Omicron variant, has continued for 55 days.

Data on deaths per million (seven-day moving average) shows a more dragged-out impact of waves. The first wave lasted 302 days, while the second lasted 223 days. The third wave, starting January 2021, has lasted 48 days.

The US has witnessed a similar trend in the last three waves. While the first wave lasted 89 days, the second was 101-day-long. The third wave was the longest, lasting 143 days, but then by the fourth wave, the period had reduced to 117 days; and the current one has continued for 67 days until now. France has witnessed a similar trend.

Brazil and India have been similar with respect to the three waves. The only country to upend the trend is the United Kingdom, where the fifth wave has lasted longer than the fourth one. The current surge in the UK has lasted fewer days than the third one (see chart 1).

In terms of deaths, though, all countries are on par as infections have been lower in the current wave than the previous two waves (see chart 2). A reason experts highlight may be the changing nature of the virus and immunity among the population.

“Two principal reasons are that the virus is becoming more infectious, so it covers more people in a shorter period of time. The second reason is that there are fewer susceptible people — who haven’t been infected — so they are covered in a shorter period,” K Srinath Reddy, president, Public Health Foundation of India, tells Business Standard.

However, that doesn’t mean the trend may continue. In the US, the case fatality rate has been higher than in other countries due to lower vaccination rates.