Imperfect vaccines

Parents

2001 Nature - Imperfect vaccines and the evolution of pathogen virulence
2015 PLOS Biology - Imperfect Vaccination Can Enhance the Transmission of Highly Virulent Pathogens
2019 Healthline - 'Leaky' Vaccines Can Produce Stronger Versions of Viruses By studying chickens, researchers say they have proven the theory that more virulent viruses can evolve from so-called "leaky" vaccines.
2021 "Vaccine efficacy isn't 100 percent - it never is," she said. "We shouldn't expect Covid vaccines to be perfect, either. That's too high an expectation."
2021 NYT - C.D.C. Will Not Investigate Mild Infections in Vaccinated Americans At least 10,000 vaccinated people were infected with the coronavirus through the end of April. Now the agency has stopped pursuing the mildest cases.C.D.C. Will Not Investigate
2021 NYT - Why Vaccinated People Are Getting 'Breakthrough' Infections
2021 Wired - The Raging Evolutionary War Between Humans and Covid-19 Fighting the pandemic isn't only about vaccines and drugs. It's about understanding how viruses mutate and change inside us, and among us.
As Read first argued in a Nature paper 14 years ago, by keeping their hosts alive, such "imperfect" or "leaky" vaccines could give deadlier pathogens an edge, allowing them to spread when they would normally burn out quickly.
Breakthrough infection
COVID-19 vaccines