Pfizer-BioNTech and Sinovac vaccines boost SARS-CoV-2 neutralizing responses Researchers in the United States and Chile have provided preliminary evidence that individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) – the agent that causes coronavirus disease 2019 (COVID-19) – mount a robust neutralizing antibody response against the virus that can be significantly boosted by two doses of Sinovac Biotech’s CoronaVac vaccine or one dose of Pfizer-BioNTech’s BNT162b2 vaccine. Immunization of infection-naïve individuals with two doses of CoronaVac or one dose of BNT162b2 also elicited similar levels of neutralizing antibodies to those observed in seropositive individuals 4.2 to 13.3 months post-infection.