The drugmakers were developing an updated version of their existing vaccine that would be made using the lineage of the Delta variant, Pfizer said on Thursday. Pfizer and BioNTech are in discussions with the US medicine regulator to finalise their clinical trial plans and expect to begin studies in August.
The companies would be the first to create a vaccine focused on targeting the Delta variant, a move that underscores concerns that the highly transmissible strain may be able to evade existing jabs and new measures will be needed to tackle it.
The Delta variant was first detected in India in December and has since swept across Europe and the US, leading to a surge in coronavirus cases, especially among unvaccinated people. Delta is now the dominant strain in the US, according to the Centers for Disease Control and Prevention, and accounts for more than 90 per cent of new Covid cases in the UK.
Pfizer reiterated that a third shot of its vaccine given six to 12 months after the second dose of its two-shot regiment would be needed in order to boost immunity against new variants.
The company said it would publish more definitive data on the effects of a third shot, and also planned to apply for emergency use authorisation from the US Food and Drug Administration in August for its booster shot.
The New York-based company pointed to preliminary data published last month that showed two vaccine doses elicited antibody titres against the Delta variant but said that vaccine efficacy was shown to decline six months after vaccination.
“While we believe a third dose of [our vaccine] has the potential to preserve the highest levels of protective efficacy against all currently known variants including Delta, we are remaining vigilant and are developing an updated version of the Pfizer-Covid-19 vaccine,” the companies said.
A study by Israel’s health ministry this week indicated that the BioNTech/Pfizer jab was 93 per cent effective at preventing severe illness and hospitalisation from Delta, but only 64 per cent effective at protecting against infection from the variant. Moderna and Johnson & Johnson have both said that early data showed their jabs produced antibodies against Delta.
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