The World Health Organization said Tuesday COVID-19 patients should take two doses of the Pfizer and BioNTech vaccine within 21-28 days, 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.
He 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 in the clinical trials, SAGE made a provision for countries in exceptional circumstances of (Pfizer) vaccine supply constraints to delay the administration of the second dose for a few weeks to maximise the number of individuals benefiting from a first dose," Cravioto said.
He added: "I think we have to be a bit open to these types of decisions which countries have to make according to their epidemiological situations."
Kate O'Brien, a WHO immunization expert, said there was no outside limit for receiving a second vaccine dose. Alluding to delays in rolling out inoculations, she added: "Nobody expected this to be easy and we are starting to see where the road bumps are and where we need to make adjustments."
The WHO's technical chief on COVID-19, Maria Van Kerkhove, said there is no indication that the coronavirus variant identified in South Africa is more transmissible than the one spreading fast in Britain.
Tedros Adhanom Ghebreyesus, WHO director-general, said he was "very disappointed" that China had not authorised entry of an international mission to examine the origins of the global coronavirus pandemic.
"Today, we learned that Chinese officials have not yet finalised the necessary permissions for the team's arrival in China," Tedros said. "I have been in contact with senior Chinese officials and I have once again made it clear the mission is a priority for the WHO."
China reported the first cases of pneumonia of unknown cause in the city of Wuhan to the WHO on Dec. 31, 2019, and closed a market where the novel coronavirus was believed to have emerged.
Health ministers called on the WHO in May to identify the source of the virus and how it crossed the species barrier.
The United States, which has accused China of having hidden the outbreak's extent, has called for a "transparent" WHO-led investigation and criticised its terms, which allowed Chinese scientists to do the first phase of preliminary research.