BioNTech/Pfizer plan to trial Delta variant vaccine in August

Pfizer and BioNTech are preparing to start clinical trials of a version of their Covid-19 vaccine targeting the Delta variant next month, amid fears that existing jabs will offer less protection against the infectious strain spreading quickly across much of the world.

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 are 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 its belief 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.

It said it would soon publish more definitive data on the effect of a third shot, and plans to submit booster data to the US Food and Drug Administration “in the coming weeks”.

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.

Latest coronavirus news

Follow FT’s live coverage and analysis of the global pandemic and the rapidly evolving economic crisis here.

“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,” Pfizer 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 show their jabs produce antibodies against Delta.