Breakthrough cases and immunity

– Agencies

DR Abraar Karan, an infectious disease doctor at Stanford University in California, suffered the same fate as many people in January. Despite being vaccinated and boosted, he got infected with Covid-19 during the surge of the highly infectious Omicron variant. Then, just a few months later in May, he performed a routine Covid-19 test one day before work and found himself infected with the coronavirus yet again.

Earlier in the pandemic, scientists held out the hope that hybrid immunity – the dual protection afforded by having been both infected with the virus and vaccinated against it – would provide the strongest shield against subsequent reinfection. The theory largely held true for versions of the virus that were less infectious than Omicron.