Breakthrough coronavirus infections – which occur even though someone has been vaccinated – are inevitable because no vaccine is 100% effective, said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.
"We see this with all vaccines, in clinical trials and in the real world. No vaccine is 100% efficacious or effective, which means that we will always see breakthrough infections, regardless of the efficacy of the vaccine," Fauci said during a virtual White House briefing on Monday.
"Influenza is the most common of this, which mutates rapidly," he added. But "even if a vaccine fails to protect against infection, it often protects against serious disease."
Fauci added that, so far, data suggest current Covid-19 vaccines offer some protection against coronavirus variants.