Vaccines may need regular updates as coronavirus evolves, say scientists

BERLIN, March 27: Scientists have assessed the course of evolution of the novel coronavirus and predicted that COVID-19 vaccines currently in use across the world may need regular updates to counter new variants of the virus which are capable of escaping the body’s protective antibodies.

The study, published in the journal Virus Evolution, assessed whether, over the long term, the SARS-CoV-2 virus is likely to demonstrate an immune evasion capability on par with that of influenza viruses.

In the research, virologists from Charite – Universitatsmedizin Berlin in Germany studied the genetic evolution of the four currently known ‘common cold’ coronaviruses, particularly the two longest – known viruses, 229E and OC43.

They traced changes in the spike protein of the these coronaviruses, which enable them to enter host cells, approximately 40 years into the past.

Based on the analysis, the scientists found one feature which was common to both the coronaviruses and the influenza virus – all three had a pronounced ladder-like shape in their evolutionary paths.

“An asymmetrical tree of this kind likely results from the repeated replacement of one circulating virus variant by another which carried a fitness advantage,” explained the study’s first author, Wendy K Jo.

According to Jo, this is evidence of ‘antigenic drift’, a continuous process involving changes to surface structures which enable viruses to evade the human immune response.

“It means that these endemic coronaviruses also evade the immune system, just like the influenza virus. However, one also has to look at the speed with which this evolutionary adaptation happens,” she added.

The scientists said the novel coronavirus genome is currently estimated to change at a rate of approximately 10 mutations per 10,000 base molecules per year, meaning the speed at which it evolves is substantially higher than that of the endemic coronaviruses. – PTI