Pfizer and BioNTech have enrolled the first participants in a clinical trial of a vaccine tailored to the Omicron coronavirus variant as the companies weigh whether they need to replace their existing Covid-19 jab.
The drugmakers on Tuesday said the study would evaluate the safety, tolerability, and efficacy of an Omicron-based vaccine candidate in 1,420 adults aged 18 to 55 years of age.
It is the first human trial of an Omicron-specific vaccine by a big western drugmaker and will play a pivotal role in determining whether Pfizer and BioNTech adjust a plan to manufacture 4bn doses of their existing jab in 2022.
The companies have said they do not expect manufacturing capacity to change if they decide to switch to a new Omicron-based vaccine. Pfizer has already begun manufacturing some doses of the new jab, which it previously said could be ready in March.
Prof Ugur Sahin, chief executive and co-founder of BioNTech, said: “Vaccines continue to offer strong protection against severe disease caused by Omicron. Yet, emerging data indicate vaccine-induced protection against infection and mild to moderate disease wanes more rapidly than was observed with prior strains.”
“This study is part of our science-based approach to develop a variant-based vaccine that achieves a similar level of protection against Omicron as it did with earlier variants.”
Several studies have shown that existing mRNA vaccines provide high levels of protection against severe disease and hospitalisation. But research published by the UK Health Security Agency last month showed effectiveness against symptomatic infection dropped to about 10 per cent some 20 weeks after a second dose.
Some epidemiologists have warned that an Omicron specific vaccine may be redundant by the time it is produced at scale given the speed at which the variant has spread. Others have urged vaccine makers to invest in multivalent vaccines that can target several different variants.
Amesh Adalja, an infectious disease specialist at Johns Hopkins Center for Health Security, said it would have been better to have an Omicron-based version of the vaccine before the variant surged. But he said it could still be beneficial if new variants sprout from Omicron and drift further from the Wuhan strain that the vaccines currently target.
“What’s really game-changing would be a universal coronavirus vaccine that targets a conserved area of all human coronaviruses,” added Adalja.
Pfizer and BioNTech said they expect to launch an additional study in the first quarter of 2022 evaluating their currently-approved vaccine, the Omicron-based vaccine candidate, and a combination of the two vaccines at varying dose levels.
Kathrin Jansen, Pfizer’s head of vaccine research & development, said: “Staying vigilant against the virus requires us to identify new approaches for people to maintain a high level of protection, and we believe developing and investigating variant-based vaccines, like this one, are essential in our efforts towards this goal.”