New COVID-19 variants and subvariants continue to be more contagious, but healthcare providers are learning more and fighting back. Here’s why and how COVID-19 continues to evolve.
health.clevelandclinic.org
Most of the time, mutations are so small that they don’t significantly affect how the virus works, or they make the virus weaker, Dr. Rhoads says. But occasionally, a mutation helps the virus copy itself or get into our cells more easily.
“If these advantageous genetic mistakes are included when the virus replicates, they’re passed on and eventually become part of the virus’s normal genome,” Dr. Rhoads explains. We can see these mutations accumulate over time, and that’s how we get new variants of a virus strain.
If you get confused about strains, variants and mutations, think of it this way: New variants of a virus strain emerge through the process of mutation. In the media, the words strain and variant are often used interchangeably.
Could some vaccines drive the evolution of more virulent pathogens? Conventional wisdom is that natural selection will remove highly lethal pathogens if host death greatly reduces transmission. Vaccines that keep hosts alive but still allow ...
www.ncbi.nlm.nih.gov
Vaccines that keep hosts alive but still allow transmission could thus allow very virulent strains to circulate in a population. Here we show experimentally that immunization of chickens against Marek's disease virus enhances the fitness of more virulent strains, making it possible for hyperpathogenic strains to transmit.
Immunity elicited by direct vaccination or by maternal vaccination prolongs host survival but does not prevent infection, viral replication or transmission, thus extending the infectious periods of strains otherwise too lethal to persist. Our data show that anti-disease vaccines that do not prevent transmission can create conditions that promote the emergence of pathogen strains that cause more severe disease in unvaccinated hosts.