COVID-19 has caused severe disruption across the world. However, there are variations both among and within countries in the number of cases and in case fatality rates. In general, Europe and the U.S. have borne the brunt of the infection, while Asian and African countries have been relatively less affected so far. It is not yet clear why such geographical differences exist; they cannot be explained by healthcare facilities alone. India had reported its first case on January 30, 2020; as of May 12, it has reported over 71,000 cases and more than 2,300 deaths. In comparison, the U.S. and the U.K., which also reported their first cases around the same time, recorded over 13,47,930 cases and over 2,24,330 cases, and over 80,600 deaths and over 32,100 deaths, respectively.
Interactive map of confirmed coronavirus cases in India | State-wise tracker for coronavirus cases, deaths and testing rates
The relatively young population of India has been suggested as a possible factor for this stark difference. However, while older people are at highest risk from the more severe consequences of COVID-19, there is no evidence to suggest that younger people are immune to the infection. Differences in case ascertainment may explain some of the patterns: South Korea and Germany tested widely in an effort to identify cases, whereas some countries including India offered testing (at least in the initial stages) to only those with a history of foreign travel or with close contact with a known case. However, this does not explain differences in mortality. Also, case fatality rates may even be an underestimation in India where a number of asymptomatic cases may go undetected.
Possible reasons for differences
Low temperature and low absolute humidity have been suggested as factors influencing transmission. But this theory needs further proof. Genetic variations may be a possible explanation. During the 2003 SARS epidemic, specific genetic variants that provided resistance or susceptibility to infection were identified in different populations. Population-specific differences such as ACE2 (which permits virus to enter the body) may partly explain the differential infection rates of COVID-19. It is also possible that some Asian and African populations have been exposed to a multitude of coronaviruses previously, which has provided some cross-immunity. The SARS epidemic did not affect South Asian and African countries significantly. The West Asian countries which bore the brunt of Middle East Respiratory Syndrome (MERS) do not appear to be significantly affected by COVID-19.
Early adoption of countrywide preventive measures may have also played an important role. While European countries reacted with restrictions and closures, it remains a question if these measures were taken too late. India closed its doors to foreign travellers early on in the outbreak and has not seen the surge that could potentially have been expected for a population of 1.3 billion people. However, Sweden for example, has still not adopted major restrictions and not seen a large surge in cases.
Easing of lockdown
If the epidemic does spread with generalised community transmission, the healthcare, social and economic implications will be significant.The lockdown in India has played a role in preventing an exponential surge in cases. However, a measured public health approach is critical in controlling this epidemic. Current approaches are largely urban-centric with little focus on rural dynamics. A decentralised approach is required to manage the large rural population, and the success in Kerala may serve as a useful model. Governments may consider mobilising and training a range of healthcare providers (including providers of primary care, and traditional healthcare systems) in responding to this situation. Crucially, the current practice of isolating all cases in hospital settings is not sustainable if cases increase.
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As it would be impractical to test everyone with symptoms, a case definition based on symptoms and local epidemiological context may be used to diagnose suspected COVID-19 cases. Those with mild symptoms (and their household contacts) should be advised to stay at home. If cases cannot be managed at home, community centres may be deployed for isolation. This approach will ensure that hospitals are available to those who really need them. The lifting of the lockdown needs to be undertaken in a phased manner. One approach would be to ensure that the vulnerable (such as the elderly and the immuno-compromised) are protected beyond initial lockdown periods, while restrictions are lifted for the majority of the healthy population. The disease has generally been mild among most people affected in the subcontinent, and it is possible that herd immunity may develop through gradual exposure among healthy individuals. While lockdown measures are lifted in a controlled manner, government public health agencies need to continue to promote hygiene measures. Physical distancing will need to be continued. Public health messages need to be locally tailored and consistent. They require not only awareness, but also resources as these are largely middle-class concepts and not easy to practice in crowded areas where there is no running water. In conclusion, the approach to the management ofCOVID-19 needs to blend acute disaster management strategies with longer-term public health measures including economic measures.
K. Kumaran, G.V. Krishnaveni, Kumar G.S. are public health epidemiologists & Giriraj R. Chandak is a physician scientis t
