Hope of Omicron booster in months as Pfizer tailors jab

Pfizer has begun the first human trial of a vaccine tailored for Omicron which may give better protection against infection.

A health worker prepares to inoculate a child with a dose of the Pfizer-BioNTech vaccine. Picture: AFP.

Pfizer and BioNTech have begun the first human trial of a vaccine tailored for Omicron, raising the prospect that bespoke boosters could be available before autumn.

Initial results from the study, which will recruit 1,420 healthy adult volunteers, are expected during the first half of the year. It is hoped that the vaccine will give better protection against infection and mild disease.

Professor Ugur Sahin, the chief executive of BioNTech, said the original vaccine that his company developed with Pfizer still gave strong protection against severe disease when faced with Omicron. “Yet emerging data indicate vaccine-induced protection against infection and mild-to-moderate disease wanes more rapidly than was observed with prior strains,” he said.

Data from the UK Health Security Agency suggests that after ten weeks a Pfizer booster gives about 50 per cent protection against mild disease from Omicron; with Delta it was more than 80 per cent.

Pfizer expects to produce four billion doses of Covid vaccine this year and this is not expected to change if a tweaked Omicron vaccine is needed.

Waning immunity was underlined by a study that has suggested two thirds of people who caught the Omicron coronavirus variant may have previously had the virus.

Research published on Tuesday by REACT scientists at Imperial College London looked at more than 100,000 swab PCR tests of volunteers taken between January 5 and January 20. About 1 in 23 or 4.41 per cent were positive and almost all of these were the ultra-infectious Omicron variant.

Of those who had tested positive for coronavirus 65 per cent said they had already caught the virus. Professor Paul Elliot, the program director, warned against concluding that all were reinfections, noting that PCR tests sometimes pick up old traces of the virus.

Dr Kathrin Jansen, head of vaccine research and development at Pfizer, said: “While current research and real-world data show that boosters continue to provide a high level of protection against severe disease and hospitalisation with Omicron, we recognise the need to be prepared in the event this protection wanes over time and to potentially help address Omicron and new variants in the future.

“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, is essential in our efforts towards this goal.”

The trial volunteers will go into three groups. The first will have had two doses of the present Pfizer-BioNTech vaccine 90 to 180 days before enrolment, and during the trial will receive one or two doses of the Omicron jab.

The second cohort received three doses of Pfizer 90 to 180 days before the study; they will receive a further dose of the present vaccine or the new one.

The third cohort has not had any vaccine yet; they will receive three doses of the Omicron-based vaccine, spread over several months.

Last month the government placed orders for 114 million extra doses of Covid vaccines to be used over the next two years.

Experts stress that steep declines in the protection conferred by boosters have been recorded only for mild symptomatic cases. Scientists expect protection against severe disease, which draws on different parts of the immune system, to last much longer. The Joint Committee on Vaccination and Immunisation, which advises British ministers on vaccine policy, is “watching the situation very closely”, health officials have said.

Jeremy Hunt, a former health secretary, said the government should think about fourth doses. “It is surely now time to start planning for further boosters as we learn to ‘live with Covid’, particularly as Israel is already going down that route,” he wrote in a bulletin issued by Patient Safety Watch, a charity.

This week the Israeli government’s vaccine advisory panel recommended a fourth dose for all adults amid surging rates of Omicron cases, becoming the first country in the world to do so.

A UK government source said last month that vaccine protection rates would continue to be monitored and there was “flexibility” to run another booster campaign when needed.

The Times