Lowering risks of Covid-19

The number of Covid-19 cases in Nepal has been increasing steeply since August. It took just a month to double the number of positive cases (from 24 August to 23 September).

Another concern about COV- ID-19 is the number of daily tests, which does not include asymptomatic cases and cases notified in low health care settings, especially in rural areas.

The average number of daily tests in the last month was around 11,000, which is far below those countries with similar populations but with low numbers of daily incidences.

Australia has tested almost eight times more RT-PCR tests than Nepal for almost less than half the number of COVID-19 cases, Malaysia has tested 1.5 times higher COVID 19- tests than Nepal even with six times lower number of cases. Moreover, New Zealand has an almost equal of tests despite its having a population that is 5.5 times smaller than Nepal’s. More investigations help reduce the chance of transmission by asymptomatic cases, and contact tracing is possible in an effective way.

In applied epidemiology, the number of secondary cases due to a typical primary case is known as the reproduction number. A reproduction number less than one implies the virus’s extinction, whereas if it is greater than one, the virus infects the population and shows disease persistence. WHO has reported the reproduction number for Nepal to be 2-4.

However, one research report (communicated in a journal) has shown that Nepal’s estimated reproduction number is around 1.3-1.5, meaning that on an average, one positive case in Nepal infects 1.3-1.5 susceptibles.

This estimation is relatively low than global findings, possibly due to significant underreporting notification data.

The number of secondary cases depends on three major factors. First, the probability or chance of infection; secondly, contact rates (between infected and susceptible); and lastly, the duration of infectious periods.

All these three components are directly proportional to the number of incidences.

The current control measures, such as lockdown, wearing masks and good sanitising habits are not enough to reduce infection probability and contact rates. However, extensively large numbers of tests reduce the probability of infection by asymptomatic cases, which is the major challenge in Nepal.

Mathematical models show that Nepal needs to increase daily tests by 5-7 times of what is currently being done to include more asymptomatic cases.

But this is an ambitious goal and needs a strong government and political commitment.