When harmful bacteria or viruses enter the body, immune cells spot telltale proteins known as antigens on the invaders’ surfaces and send out armies of antibodies to fend them off. If some of those antibodies have just the right shape, they can latch onto and block the antigens like the key to a padlock.

But our immune systems don’t always have the right antibodies to fight a particular invader. So over the past few decades scientists learned to work with animals such as camels and llamas, and to use synthetic design techniques in the lab, to generate antibodies that can be turned into medicines.

More than 85 antibody therapies have been approved by the FDA to date, including two granted emergency authorization for treating COVID-19. Read more