Single dose Janssen jab poised to join UK’s vaccine arsenal

A new Covid-19 vaccine, currently undergoing trials in the US, is likely to get the green light for use in the UK within a matter of weeks. This would make the Janssen vaccine the fourth to be approved by the MHRA, but the first of its kind in one crucial respect: it only requires one dose.

Janssen, the Belgium-based vaccine arm of American pharmaceutical giant Johnson & Johnson, plans to have results from its large-stage clinical trials ready by the end of January.

Johnson & Johnson said: “If the vaccine is safe and effective, an emergency use authorization application could be submitted to the FDA [Food and Drug Administration] in February.” The UK, which has already secured 30 million doses of the jab, will likely provide authorisation in parallel.

Preliminary evidence from the trials, involving 40,000 participants, is encouraging. Dr Moncef Slaoui, chief adviser for the US vaccination programme, Operation Warp Speed, predicts J&J’s vaccine will be about 85 per cent effective.

Meanwhile in the UK, Sir John Bell, Regius Professor of Medicine at the University of Oxford and an adviser to the UK’s Vaccine Taskforce, told The Telegraph that the vaccine was “highly likely to work”.

A single dose jab could provide a significant advantage. With existing Covid vaccines, questions surrounding double doses have caused complications. Opinions are still divided on the level of protection provided by a single dose and on whether the UK’s decision to delay second doses of the vaccine was a sensible one.

Crucially, not only would a single jab be simpler to administer but Janssen will also help to clear up some of the ambiguities about single dose-effectiveness thanks to a second, two-dose trial the firm is running.

Janssen’s comparative trial involves 30,000 participants worldwide, including 6,000 in the UK, with volunteers being given two doses of the vaccine around two months apart. The trial will take longer to complete – perhaps another six months – but it will provide much-needed answers on the extent to which a second dose can provide stronger and longer-lasting immunity.

Janssen developed its Covid-19 vaccine using a technology similar to the one used to create its European Commission-approved Ebola vaccine, which shares similarities to the Astra Zeneca/Oxford vaccine.

All three are known as ‘vector vaccines’. And both the Janssen and Oxford vaccines rely on DNA technology to prompt an immune system response, as opposed to the mRNA technology used in Pfizer and Moderna vaccines. The Janssen jab delivers coronavirus DNA through a deactivated common cold virus. Astra Zeneca uses the same method but substitutes a human cold for one found in chimpanzees.

Crucially, much like the AstraZeneca vaccine, the Janssen vaccine is easy to transport because it can be stored at regular refrigerator temperatures as opposed to the special deep freezers required for mRNA vaccines.

Janssen, like AstraZeneca, has agreed to provide doses for emergency pandemic use on a not-for-profit basis.

If Sir John Bell’s predictions are correct, then supplies of the Janssen jab may well arrive in time to help the UK Government fulfil its ambitious aim of vaccinating 13 million Brits by mid-February.