COVID-19 vaccine: WHO recommends two doses of Pfizer-BioNTechs jab in 21-28 days January 6th, 2021 COVID-19 vaccine: WHO recommends two doses of Pfizer-BioNTechs jab in 21-28 days January 6, 2021Technology COVID-19 vaccine: WHO recommends two doses of Pfizer-BioNTechs jab in 21-28 days January 6th, 2021