COVID-19 vaccine effectiveness for one dose of the Pfizer/BioNTech or the AstraZeneca/Oxford vaccine against the Delta variant (B1617.2) was much lower compared with one-dose effectiveness against the Alpha variant (B117), according to a UK study yesterday in the New England Journal of Medicine.
Two doses, however, narrowed the gap.People are generally considered fully vaccinated with the Pfizer and the AstraZeneca vaccines 14 and 15 days after the second dose, respectively.The Public Health England-led research team said that their observational, case-control study underscores the urgency of increasing uptake of two doses of a COVID-19 vaccine among vulnerable populations.