The UK National Health Service has pushed back the window for people to receive the second dose of the COVID-19 vaccine made by Pfizer and BioNTech, to a duration that companies tested in only a small percentage of patients.
The NHS wrote a letter to hospitals saying those who should receive their second dose after 4 January should be rescheduled from three weeks to 12, with most recipients booked in the last week of that period. The measure would bring the window closer to the time period for the newly approved vaccine made by Oxford University and the pharmaceutical company AstraZeneca AZN,
Read: The UK now has enough vaccine to “cover the entire population” following the authorization of AstraZeneca-Oxford’s COVID-19 vaccine
The NHS said the measure would protect the largest number of people at risk in the shortest period and would have the greatest impact on mortality.
Confirmed cases of coronavirus have increased over the past month, and the UK said a new variant of the virus that causes COVID-19 is more easily transmitted. Daily cases have gone from 12,330 in late November to 50,023 on Dec. 30.
When the UK Medicines and Health Products Regulatory Agency urgently approved the vaccine from the US pharmaceutical company Pfizer PFE,
and its German partner BNTX,
said the interval between doses should be at least three weeks and was based on analyzes that included patients who received their second vaccination between 19 and 42 days after the first vaccination.
Pfizer said the safety and effectiveness of the vaccine have not been tested in the new range. “The Pfizer and BioNTech phase 3 study for the COVID-19 vaccine was designed to evaluate the safety and efficacy of the vaccine following a 2-dose program, separated by 21 days. The safety and efficacy of the vaccine have not been evaluated in different dosing schedules, as most trial participants received the second dose within the window specified in the study design, ”he said. the company.
Pfizer also noted that there is no evidence that protection is maintained within 21 days of receiving the first dose.
“While decisions about alternative dosing regimes are up to health authorities, Pfizer believes it is critical that health authorities make efforts to monitor any alternative program implemented and ensure each recipient receives the maximum possible protection, which means vaccination with two doses of the vaccine “. said Pfizer. The message left with BioNTech was not returned immediately.
The information document provided by pharmaceutical companies to the U.S. Food and Drug Administration stated that about 80% of patients receiving the second dose were given it within ten weeks of taking it. the first.