VACCINE BREAKTHROUGHS

Virus variants in the spotlight as number of reinfections and breakthroughs rise

- FM BUREAU

Even as India is trying out various models to fine-tune and scale up its vaccination strategy, more and more cases are coming up involving re-infections and breakthrough infections — where the infection takes place despite the completion of a full course of vaccination.

To make matters worse, many such cases are being reported among the frontline warriors, especially in healthcare settings.

Rising infections

India has been witnessing a sudden and sharp increase in the number of COVID-19 infections in recent weeks, starting in Maharashtra in March and subsequently spreading to other states including Delhi, Uttar Pradesh, Chattisgarh, Tamil Nadu, Karnataka and Kerala.

Take the case of Delhi, where daily case numbers have gone from less than 1,000 to nearly 23,000 in a matter of four weeks. Here, serosurveillance reports conducted before the latest surge had indicated the presence of SARS-CoV-2 antibodies in over half the population.

Therefore, the sudden surge of new infections points to a dreaded phenomenon — ‘immune escape’ — where a virus acquires sufficient mutations in its genome to escape detection by the antibodies generated by the human body during previous rounds of infection.

The case in favor of immune escape is based on two pieces of evidence: the rising number of reinfections among those who were supposed to be immune due to previous infections or vaccination, and early data pointing to the presence of a large number of mutant strains in states like Maharashtra and Kerala. Studies conducted in places like Delhi and Uttar Pradesh are unlikely to give a vastly different picture.