Pfizer and BioNTech vaccine within a period of 21-28 days, the World Health Organization said on Tuesday as many countries grappled with a more highly infectious coronavirus variant."We deliberated and came out with the following recommendation: two 2 doses of this vaccine within 21-28 days," Alejandro Cravioto, chairman of WHO's Strategic Advisory Group of Experts on Immunization (SAGE), told an online news briefing.Also Read | India’s hunt for the new Vision 2020He said SAGE did not recommend the Pfizer jab for travellers unless they were in a very high-risk group due to the very limited supply of anti-Covid drugs at present."While we acknowledge the absence of data on safety and efficacy after one dose beyond the three-four weeks studied.