What new Covid-19 variants mean for our fight with the virus

For more than three months the patient struggled against Covid-19. His immune system was already in a bad way when he caught the virus – he had been receiving a drug treatment for lymphoma, a type of blood cancer, that depleted some of his immune cells. With fewer of the usual defences against infection, the virus was able to spread in his body relatively unchecked. As doctors tried to help the elderly patient fight the virus, they gave him blood plasma collected from people who had already recovered from Covid-19. Contained within this milky-brown liquid – also known as convalescent plasma – were antibodies against the virus that might help to neutralise it. Over the course of 101 days as they treated the man, clinicians at Addenbrookes Hospital in Cambridge, UK, took 23 swab samples as he fought against the disease. Each swab was sent off to a nearby laboratory to be analysed. But when virologists looked at the virus’s genetic material in the samples, they noticed something astonishing – Covid-19 was evolving before their eyes.