The study also found that there was no significant difference in vaccine effectiveness if people who were previously infected received one dose or two doses, supporting evidence from other studies that showed one dose was sufficient in protecting people with prior Covid-19 infections from reinfection.
These findings may have implications for vaccine policies.
Shane Crotty, a virologist and professor with the Center for Infectious Disease and Vaccine Research at the La Jolla Institute for Immunology, told CNN that it would be "quite reasonable" to have a policy in the US that required people with previous coronavirus infections to get only one dose of a vaccine, based off the results of this research. Crotty was not involved with either study.
Ronen Arbel, lead researcher on this study and a health outcomes researcher at Clalit Health Services in Israel, believes that more countries should adopt a policy like what the Israeli Ministry of Health implemented in March 2021, when it recommended a single dose of vaccine for people who had recovered from Covid-19, to be given three months after their primary infection.
"If you recovered from Covid-19, it's like you got a primary vaccination," Arbel told CNN.