The second injection of the vaccine against the coronavirus developed by the Pfizer and BioNTech laboratories can be delayed by a few weeks in “exceptional circumstances”, experts from the World Health Organization (WHO) said on Tuesday.
The Strategic Advisory Group of Experts (SAGE) on immunization “recommends the administration of two doses of this vaccine within 21 to 28 days,” its chairman, Alejandro Cravioto, told a press conference. by indicating that it was possible to delay the administration of the second injection by a few weeks “in exceptional circumstances of epidemiological contexts and supply constraints”. This will allow “to maximize the number of people benefiting from a first dose”, he explained.
No more than six weeks between two doses
During the same press conference, Kate O’Brien, director of the immunization and vaccines department at WHO, warned that the deadline could not exceed six weeks.
This announcement by WHO experts comes as the BioNTech laboratory warned Tuesday that the maximum effectiveness of its vaccine against Covid-19 was not demonstrated if the second injection is delayed, a strategy applied or considered by several countries to vaccinate more people. “The efficacy and safety of the vaccine have not been evaluated for other dosing schedules” than the two injections spaced 21 days apart applied during the clinical trial, explained the German company, which developed with the American laboratory Pfizer the first vaccine authorized in the United States and in the EU.
Faced with limited stocks of this product, Denmark announced Monday to space the two doses up to six weeks; the UK, which authorized the vaccine before the EU in early December, allows up to 12 weeks to elapse between the two injections.
In Germany, the health ministry has asked health authorities to assess options to extend the deadline, according to a document consulted Monday by AFP.
A list of recommendations for the vaccine
The WHO expert group made a whole series of recommendations on Tuesday regarding the Pfizer / BioNTech vaccine against Covid-19. In particular, they recommend that the vaccine be administered only in settings where anaphylactic shock (a severe allergic reaction) can be treated.
Due to the lack of data on pregnant and breastfeeding women, experts prefer not to make recommendations at this time. Alejandro Cravioto stressed, however, that “the benefits of immunizing pregnant women outweigh the potential risk” in some cases, such as in the case of health workers at high risk of contagion. And if a woman is in a high risk group, “we recommend vaccination without stopping breastfeeding,” he said.
In addition, the expert group does not currently recommend vaccination of international travelers, unless they are part of a high-risk group.
Finally, noting that current data shows that symptomatic reinfection within six months of a first infection is rare, they recommend that people who have tested positive through a PCR test in the previous six months to delay vaccination until the end of this period.