We published an article on the momentum of the second wave of Covid-19 in India on May 13 and concluded that the numerical peak of the second wave got over on May 6. It has been suggested that this may be artifactual because the daily number of tests for Covid-19 has come down in some states and therefore the number of new cases may be underestimated. However, the fact that the test positivity rate is also decreasing (from 22.6% on May 8 to 19% on May 15) concurrent with the decline in number of new cases supports our contention that the second wave peak is over. Is there any other corroborating evidence that it is over?
We applied the same technique that we used to track the momentum of the second wave - acceleration-deceleration graph - for analysing deaths during the second wave using a seven-day rolling average. Our graph shows that acceleration of deaths due to Covid-19 peaked in India on April 28 and from then onwards, there has been a decline in the speed with which mortality figures were increasing. Our analysis indicates that the 'numerical mortality peak of the second wave' will occur soon - within the next one week - and from then on, the number of deaths will steadily decline.
The time interval between the momentum peak of the second wave on April 21 and the acceleration peak of mortality on April 28 is the average lag time between diagnosis of infection and death in India. Normally it would take about three weeks from infection to death. The shortened lag time indicates that patients are being diagnosed late, maybe because they do not get tested as soon as they have symptoms due to the temporary stigma and fear of social exclusion that the diagnosis entails.
The practical implication of our observation is that we are likely to see a decrease in demands for oxygen, hospital admissions, ICU beds and drugs like remdesivir in the next two-three weeks.
It is very important to encourage people, particularly those who are unvaccinated and those at high risk of serious disease and death - the elderly and people with comorbidities like diabetes, hypertension, heart, liver or kidney disease - not to ignore mild symptoms but to get tested early so that admission delays are avoided and specific therapy instituted in time to save lives.
Individual states and districts are likely to have differing rates of acceleration of mortality; they would do well to analyse their mortality data using our technique to formulate and implement regional policy.
Dr M S Seshadri
Medical Director, Thirumalai Mission Hospital, Ranipet and former Professor of Medicine and Clinical Endocrinology, CMC, Vellore.
Dr T Jacob John
Former professor of Clinical Virology, CMC, Vellore.
(mandalam.seshadri@gmail.com, tjacobjohn@yahoo.co.in)