Next-generation Covid-19 vaccines are supposed to be better. Some experts worry they could be worse
With Covid-19 vaccines, the world hopes to beat back the virus that causes the disease. But some scientists are increasingly concerned that, because of a quirk of our own biology, future iterations of the vaccines might not always be quite as effective as they are today.
The concerns stem from a phenomenon that is known as imprinting, sometimes called original antigenic sin, which is believed to affect how we respond to some pathogens.
