Vaccines Show Declining Effectiveness Against Infection Amid Delta Variant

Three studies published Wednesday by the Centers for Disease Control and Prevention show that protection against the coronavirus given by vaccines declined in the midsummer months when the more contagious delta variant rose to dominance in the United States.

At the same time, protection against hospitalization was strong for weeks after vaccination, indicating the shots will generate immune fighters that stave off the worst effects of the virus and its current variations.

Data from these studies persuaded the Biden administration to develop a plan for additional doses to bolster the immune systems of people vaccinated months earlier. The Biden administration will begin offering coronavirus booster shots to fully vaccinated adults who received the Pfizer-BioNTech and Moderna shots the week of Sept. 20, top health officials announced Wednesday, after concluding that a third shot is needed to fight off waning immunity.

“Examining numerous cohorts through the end of July and early August, three points are now very clear,” CDC director Rochelle Walensky said at a White House covid-19 news briefing Wednesday. “First, vaccine-induced protection against SARS-CoV-2 infection begins to decrease over time. Second, vaccine effectiveness against severe disease, hospitalization and death remains relatively high. And third, vaccine effectiveness is generally decreased against the delta variant.”

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Source: Ben Guarino, Laurie McGinley, the Washington Post