Boosters Will Help Curb Delta Or More Dangerous Variants, Say Scientists

Fully vaccinated individuals infected with the variant have peak virus levels in the upper airways as high as those lacking immunity, a large study from the U.K. showed last week.

The roll out of a third dose of Covid vaccine has sparked debate on ethical and political grounds, since a large swath of the human population is yet to receive any inoculation. But the case for boosters on scientific grounds is building. The reason is delta. The most-infectious coronavirus variant to emerge so far is in a race with the human immune system, and there's mounting evidence that delta is winning -- at least initially. Fully vaccinated individuals infected with the variant have peak virus levels in the upper airways as high as those lacking immunity, a large study from the U.K. showed last week. That suggests people with delta-induced breakthrough infections also may be capable of transmitting the virus, frustrating efforts to curb the Covid pandemic. Waning antibody levels in some highly vaccinated populations such as Israel have prompted calls to offer boosters to blunt fresh waves of hospitalizations.  "The science is the boosters work, and they will definitely help," said Shane Crotty, a virologist and professor at the La Jolla Institute for Immunology's Center for Infectious Disease and Vaccine Research in California.