Dr. Rochelle Walensky, the head of the Centers for Disease Control and Prevention (CDC), said that data sourced from Israel on COVID-19 vaccines show that the efficacy of the shots has dropped among individuals who received their vaccines early on. Citing three studies that were released by the CDC’s Morbidity and Mortality Weekly Report, Walensky said on Aug. 18 that the vaccines’ efficacy decreases over time in preventing infection. Although protection against death and hospitalization is “holding up well,” the COVID-19 vaccines’ effectiveness is “waning” in even preventing severe illness or death, she added. “Even though our vaccines are currently working well to prevent hospitalizations, we are seeing concerning evidence of waning vaccine effectiveness over time and against the Delta variant,” Walensky said during a news conference, in explaining why federal officials are now recommending that booster shots be given to Americans eight months after they’ve been vaccinated with the Pfizer …