The only infectious disease to have been entirely eliminated till date, according to the World Health Organisation (WHO), is smallpox. It took nearly 200 years after a vaccine was developed to prevent smallpox, caused by a virus.
Covid-19 is a one-and-a-half-year-old disease. Now, scientists are noticing that “immunological characteristics” that “govern the transition of Covid-19” are indicating an “endemicity” of the coronavirus infection.
The researchers examining the current Covid-19 pandemic trend and comparing it with past pandemics are of the view that the coronavirus infection may become endemic, and end as a seasonal illness.
They have developed a model to predict the outcome of the Covid-19 pandemic. The success of the model depends a lot on how efficiently vaccination drives are undertaken worldwide and also on the behavioural containment practices adopted by the public and government agencies.
“Our analysis of immunological and epidemiological data on endemic human coronaviruses (HCoVs) shows that infection-blocking immunity wanes rapidly but that disease-reducing immunity is long-lived,” the researchers said.
“Our model, incorporating these components of immunity, recapitulates both the current severity of SARS-CoV-2 infection and the benign nature of HCoVs, suggesting that once the endemic phase is reached and primary exposure is in childhood, SARS-CoV-2 may be no more virulent than the common cold,” the scientists said.
This prediction of Covid-19 reducing in effect to an illness like common cold is based on the evidence of past pandemics. The 1918 Spanish Flu pandemic that is often compared with the current Covid-19 pandemic had become endemic after two years.
The H2N2 pandemic of 1952, the H3N2 pandemic of 1968 and the H1N1 pandemic of 2009 too saw transitions to endemic stages. Interestingly, none of these pandemics needed rollout of vaccines for them to come to an end.
Also, none of these pandemics attained herd immunity — that has been so much talked about during Covid-19 — before turning endemic. This gives hope that Covid-19 pandemic too would become less infectious and troublesome with time, and body’s immune system would learn to fight off pathogens either through natural infection or vaccination.
However, there is one contrasting fact that sets Covid-19 pandemic apart from the previous pandemics. Past pandemics — Spanish Flu, H2N2 pandemic, the H3N2 pandemic and the H1N1 pandemic — were caused by the influenza viruses. Covid-19 is the first pandemic caused by a coronavirus.
