Study shows strong 1-dose immune response with Pfizer vaccineA single dose of the Pfizer-BioNTech COVID-19 vaccine was immunogenic in 92% of recipients, with no difference in immunogenic response between men and women but a decreasing response among older recipients, researchers from Israel's Bar-Ilan University reported yesterday in Eurosurveillance.The research also showed that, among those with previous evidence of infection with SARS-CoV-2, the virus that causes COVID-19, the immune response to a single dose was significantly stronger.In the study, 514 Israeli healthcare workers received the vaccine and had their antibody levels measured before vaccination and 21 days after the first dose.