Two doses of either the Pfizer or Oxford-AstraZeneca vaccine offer similar protection against symptomatic SARS-CoV-2 infection to that coming from natural immunity after infection, an ongoing study of healthcare workers has found.
None of the 1,456 healthcare workers at Oxford University Hospitals (OUH) NHS Foundation Trust who had received two vaccines had a symptomatic infection when followed up more than 14 days after their second vaccination. The same high level of protection was seen in unvaccinated healthcare workers who had contracted COVID-19 naturally; they had 98% fewer symptomatic infections than unvaccinated individuals who had not been infected before.
Most of the healthcare workers studied had only received one vaccine to date. Protection against symptomatic infection was lower – at 67% – after a first dose of vaccine – received by 11,023 hospital staff.
The findings were the latest data from ongoing analysis of symptomatic and asymptomatic staff testing for SARS-CoV-2 at OUH’s four hospitals and associated facilities. In total, 13,109 healthcare workers have participated.
Of these, 8,285 have received the Pfizer-BioNTech vaccine (1,407 of them two doses) and 2,738 the Oxford-AstraZeneca vaccine (49 of them receiving both doses).