Dr. Milan Bimali and Dr. Yadav Pandey
COVID-19 (corona virus disease), a respiratory disease, originally identifiedin Wuhancity in Hubei province of China in Dec, 2019 has evolved from a provincial health concern to a global pandemic with an unparalleled rapidity. As of 04/01/2020 there are than 8.5 lakh confirmed cases of COVID-19with over 40 thousanddeaths worldwide.
Nepal, with its first reported case in late January, followed by almost two months of eerie calmness, saw another 4 cases in late March within less than 10 days. It is hard to pinpoint if the relatively fewer number of cases is a stroke of luck or due to insufficient testing. The media is awash with opinions from established as well as self-proclaimed virologists and infectious disease specialist. However other than the number of positive cases, and recoveries, there has been little reporting on the forecasted course of the disease. The relatively fewer number of cases make future predictions challenging, but it is the best available data. There are dozens of models, each with a unique set of assumption and data requirements, that have been developed and employed to summarize and predict COVID-19 related health outcomes. The idea of developing a global model that is useful for every country is unlikely to come to fruition. A more realistic approach would be to make predictions taking into account the information available at local level (nationally and/or regionally).
In this article we employed the SIR model to generate estimates that could be of interest to health care professionals, policy-makers, and general population. The SIR model, which is arguably most simple model, takes into account Susceptibility (uninfected people at risk), Infection (number of people infected), and Recovery (number of people recovered).
The reported number of confirmed cases are 5 as of 04/01/2020. The gap between first and second case is approximately two months. The number of days between rest of the cases are within 1-2 days.The third cases and later were reported after government lockdown. The big gap between first 2 cases and the limited number of cases skew the findings when all 5 cases are considered. The primaryanalysis, uses the later 4 cases. A supplementary analysis was also carried taking into account all the 5 cases. The analysis makes the following assumptions: population of Nepal (people living inside Nepal as of 04/01/2020 and assumed to be static during the forecasted period) is2.5 crores; the mortality rate is 3% (based on reported mortality rate for India - Nepal’s closest match in terms of demographic, lifestyle and other factors https://timesofindia.indiatimes.com/india/why-its-too-early-to-assign-a-mortality-rate/articleshow/74883131.cms). The estimates are based on 4 cases can be unstable for making concrete inferences. The reported estimates must be taken with a grain of salt. A few more cases of reporting over the next few days could lead to drastically different estimates.
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The findings from SIR model suggest that the estimated days to peak infection will likely occur in mid-June (87 days since 03/23/2020); with estimated cases of infections exceeding 13 lakhs. At a 3% mortality rate, this translates into over 39000 deaths. The basic reproduction number suggests that on average every 10 infected people will infect 14 uninfected people. The estimates are much optimistic if all the 5 cases are considered; with 12 infections at peak; 1 death; and basic reproduction number of 1.
With treatment still a work-in-progress, a huge fraction of economically disadvantaged population unlikely to sustain prolonged lockdown; health care workers and safety officers fearing their own health and safety; scarce health infrastructures; corruption report of leaders transmogrified into leakers contributing to diminished faith in government and bureaucracy; andreliance on other countries (who are facing acute shortages on their own) for medical supplies, there looms an imminent threat of actual numbers surpassing the estimates. While the aphorism “prevention is better than cure” has never been more relevant than now, as of current “prevention appears to be the only available cure”.
Disclaimer: The view and findings reflect author’s own/personal work and bear no relation to the institution they are professionally affiliated with.
