Need to monitor morbidity due to Covid-19: Expert

'It is quite possible that in the next four to six months mortality due to Covid-19 will decline further. This will reduce the fear of the disease, facilitating opening up of the economy further,' Dr Naresh Purohit, Epidemiologist and visiting Professor at the Kolkata-based West Bengal University of Health Sciences, School of Public Health, told UNI here.

According to him, though the Covid infection graph is rising in the country month by month, the mortality figure seems to be on the decline after June. 
'However, long-term morbidity needs to be monitored,' he stressed.

'In Gujarat, the mortality rate touched a high of nearly 7 per cent in April; it has come down to 2-3 per cent in August. A decline has also been observed in Maharashtra, the state most affected by the pandemic: It has fallen from 4 per cent to less than 3 per cent in this period,' the renowned Epidemiologist said over phone. 

'In Karnataka, another badly-affected state, it has gone down from 4 per cent to 1.6 per cent. Medics treating COVID-19 patients have observed that the cases being admitted to hospitals in July and August were clinically much milder compared to those admitted in April or May,' Dr Purohit pointed out.

The physician, who is also the Advisor to the National Integrated Disease Surveillance System Programme, stated that there could be many possible explanations for the declining mortality rate. 

'Firstly, there is a strong possibility that the virus is losing its virulence and that is why we are witnessing clinically milder cases. This has been noticed during past epidemics as well. For example, during the initial phase of the swine flu epidemic, the cases were very severe and health conditions of patients deteriorated rapidly leading to very high mortality. However, in about a year, cases became much milder and now swine flu cases do occur but with very low mortality numbers,' he said. 

Similar observations were documented during the Chikungunya virus epidemic in 2006. The disease caused high mortality in the initial phase, which declined after some months. During recent times chikungunya is a relatively milder disease, and mortality is very rare, Dr Purohit observed.
The second explanation is that in the case of relatively new infectious diseases, medics and hospitals are not prepared to treat and manage the affliction as the epidemiology and clinical profile of such diseases are not known completely. 

'For COVID-19, there was initially no known antidote, but later, various modalities of treatment were developed — use of high-flow nasal oxygen instead of the early use of ventilators, making patients admitted to ICU lie in the prone position instead of the supine position, and the use of corticosteroids, anticoagulants, remdesivir and other antiviral drugs. Clinicians are now better equipped in terms of skills while treating COVID-19 patients and managing those with severe symptoms,' the renowned physician pointed out.

'India’s health system has also come up with evidence-based guidelines that assisted in bringing in a semblance of uniformity in-patient care across the country. Engagement with private providers and enhancement of testing modalities and guidance on isolation and quarantine, further assisted in early detection and breaking the chain of transmission,' he stated.

Patients and communities have been motivated by disseminating appropriate information about reaching doctors and hospitals early. Efforts have been enhanced to generate awareness about the new norms pertaining to the use of masks, hand washing and social distancing. Testing has become more widespread and accessible. All this has meant that diagnosis happens early, helping to control complications.

Dr Purohit said in the first phase of the epidemic, the disease spread to the most congested part of metro cities. 'Given the very dense population, infective doses could have been high. Serological surveys show a high percentage of people in slums in parts of Maharashtra have antibodies. In contrast, in June, July and August, the epidemic spread to the less dense population of several cities, which have a better socio-economic profile. The comparatively less proximity between the carriers of the virus and their contacts could have reduced the pathogen’s infective dose.

'The nutritional and immunological status of the better-off population infected in June, July and August could also have contributed to relatively milder infection in the later part of the pandemic,' he explained.

'The decline in mortality rates is not specific to India. This was seen in China as well. Mortality in Wuhan was much higher than the rest of China, where mortality is less than  one per cent. The new wave of infections in Europe also shows a much-reduced mortality rate compared to that in March, April and May,' the medic noted.

Quoting from his recent research data, the Epidemiologist attributed that one important reason for low mortality was that the Integrated Disease Surveillance System (IDSS) collecting data of the disease and deaths has not been allowed to function according to the rules as many states have taken the control of data to the office of health ministers. 

'Due to this reason, clear-cut numbers have not been given to them and data collection and assimilation has been very poor.Maharashtra, West Bengal and Telangana did not include cases of death where co-morbid conditions were high, in their data from from April to June,' Dr Purohit said.