Why a teenager's bird-flu infection is ringing alarm bells for scientistsA strain of avian influenza shows mutations that may improve its ability to infect humans, but human-to-human transmission has not been observed.
COVID Patient's Infection Lasts Record 613 Daysand Accumulated Over 50 MutationsA patient with a weakened immune system harbored a highly mutated Covid-19 strain for over 600 days, showcasing the risk of prolonged infections in immunocompromised individuals.