evidence: Israeli data has also suggested that the Pfizer-BioNTech vaccine’s effectiveness against infection dipped to as low as 39 percent between June and July, down from the previous 64 percent. [...] Estimated effectiveness of Pfizer-BioNTech vaccineVaccine effectiveness was 87 to 96 percent for all outcomes before Delta, but now it’s 39 to 84 percent effective against infection and 75 to 95 percent effective against hospitalization. [...] One study that observed nursing home residents found that the Pfizer-BioNTech vaccine’s effectiveness against infection was 74.2 percent before Delta, and this dropped to 52.4 percent when Delta dominated.