There are attempts to draw parallels betwen the Covid-19 pandemic and the Spanish influenza of 1918-19, the most devastating pandemic in the recent history, which claimed an estimated 20–50 million lives.
Trends of the Spanish Flu
India was the focal point of the Spanish Flu a century ago. The disease hit India in two waves—the starting milder attack followed by a severe wave in the Autumn of 1918. The disease is believed to have been brought to India by World War I soldiers, who returned home. The study found that with the passage of time, the severity of the epidemic diminished, the velocity of the wave slowed down; the wave grew longer in duration; and the eastern portions of India were the last to experience the pandemic.
How It Gradually Abated
The following reasons could be cited as possible causes that led to its eventual decline.
(i) By the time the flu reached Calcutta (now Kolkata), people became aware about the disease and so were practising social distancing and taking other preventive measures that people in Bombay and Madras had not been able to take because the disease caught them unawares.
(ii) The virus evolved as it spread across India, becoming milder in the process. As per a theory, as virus propagates, the more virulent strains are unable to survive, reproduce, and propagate as effectively as the less virulent strains because their hosts die before the virus can jump to new susceptible hosts. Thus, the composition of the virus gets changed in an infected population to less virulent strains from more virulent strains and as a result the disease becomes easier to tame.
(iii) Differences in climate across India could also be an important reason because flu viruses tend to not do as well in warm and moist conditions as they do in cooler and drier conditions.
Though it cannot be precisely ascertained as to which one of the three reasons led to the decline of infection, the Sanitary Commissioner did draw a correlation between the ‘crucial summer monsoon rains’ and the virulence of the disease low mortality rate, along the coastline was striking, which lent support to the ‘humidity hypothesis’.
Relevance for Today
As India is under the grip of COVID-19 pandemic the importance of studing similiar scenaris as 1918 pandemic cannot be undermined.
It is to be noted in scenarios resembling the 1918 pandemic as it evolved in India, locations close to an entry point have extremely short windows of time to deal with a virulent pathogen, which emphasises upon the need of emergency management of a short and severe wave of illness.
Locations distant from entry point have prolonged windows of time, their task is prolonged by the more gradual build-up and subsisdence of the epidemic wave.
Another crucial takeaway for India from the 1918 scenario is that if a dampening wave of mortality in case of 1918-19 pandemic was indeed caused by increased awareness, then it provides us with very important information, i.e., to remain extra cautious and practise aggressive social distancing.
In order to dampen the wave of infections so as to prevent ICUs in India from becoming overwhelmed, it is of prime importance that social distancing norms are strictly adhered to.