A small percentage of people fully vaccinated against COVID-19 still will develop the illness. These are called “vaccine breakthrough cases.” The St. Louis County Department of Public Health recently identified 71 people who tested positive for COVID-19 after they were fully vaccinated, as reported in this KSDK story.
Rachel Presti, MD, PhD, associate professor of medicine, and her WashU Med colleagues, are trying to figure out who is more likely to develop a breakthrough case. They have started a clinical trial in which participants provide blood samples so the researchers can determine which virus variant the study participants had and to study how participants’ immune systems worked against the virus. The researchers are still gathering data, but Presti’s confidence in the vaccine remains high.
“The 95% efficacy isn’t 100% efficacy, and so people do get infected,” Presti said. “What we’re hearing so far is really reassuring that the vaccines do work. We still recommend highly that people get vaccinated.”