US pharmaceutical company Pfizer Inc. said that it has no data to establish that single dose of its Covid-19 vaccine would provide protection against the virus after more than 21 days, undercutting the observation of UK’s Joint Committee on Vaccination and Immunisation (JCVI). The UK government announced a new immunisation strategy after the committee recommended inoculating as many people as possible with the first dose before offering others their second dose.
In its advisory published on Wednesday, the JCVI said that in order to maximise benefits from the vaccination programme in the short term, the second dose of AstraZeneca’s vaccine can be offered 4 to 12 weeks after the first dose. It further stated that the second dose of Pfizer-BioNTech vaccine can be offered between 3 to 12 weeks after the first dose.
“Pfizer and BioNTech’s Phase 3 study for the Covid-19 vaccine was designed to evaluate the vaccine’s safety and efficacy following a 2-dose schedule, separated by 21 days,” Pfizer said in a statement, adding that there are no data to demonstrate that protection after the first dose is sustained after 21 days.
Pfizer’s statement comes after the head of the UK medicine regulator, Dr June Raine, said that the updated guidance for Pfizer-BioNTech vaccine allows for a “potentially longer interval” than previously recommended. The pharmaceutical giant has urged the UK health authorities to remain vigilant while introducing different dosing regimens. Pfizer stressed that it is important to conduct surveillance efforts on any alternative schedules.
Meanwhile, the Medicines and Healthcare products Regulatory Agency (MHRA) has approved AstraZeneca’s Covid-19 vaccine, AZD1222. The Phase 3 trials of AZD1222 against SARS-CoV-2 across two different dose regimens showed an average efficacy of 70.4%, with no hospitalisations or severe disease observed in the vaccinated groups from three weeks after the first dose. UK health secretary Matt Hancock said that the approval was “good news for the whole world” due to its cost and storage feasibility.