High-profile COVID-19 vaccines developed in Russia and China share a potential shortcoming: They are based on a common cold virus that many people have been exposed to, potentially limiting their effectiveness, some experts say.
A handout photo shows an employee demonstrating vials with “Gam-COVID-Vac” vaccine against the coronavirus developed by the Gamaleya Institute, Moscow, Russia August 7, 2020. (The Russian Direct Investment Fund (RDIF)/Andrey Rudakov/Handout via Reuters)
A file photo shows researcher works at a lab of a Chinese vaccine maker CanSino Biologics in Tianjin, China. (Reuters)