Leiden-based pharmaceuticals company Janssen Vaccines is to start further trials of a potential coronavirus vaccine in the Netherlands, Spain and Germany in September, the company has confirmed.

Janssen, part of the giant Johnson & Johnson pharmaceuticals group, has already begun trials of the vaccine in Belgium and the US, where it is quicker to get permission for human testing.

The study currently underway involves giving participants two vaccinations, eight weeks apart. ‘In September we will look at giving less of the vaccine and if the interval can be made shorter,’ research leader Hanneke Schuitemaker told television programme Nieuwsuur on Monday evening.

The trials will be managed by Utrecht and Leiden teaching hospitals, among others, according to the Financieele Dagblad.

Four pharmaceuticals companies are currently in phase three of testing a potential coronavirus vaccine involving major human trials, and Janssen Vaccines hopes to enter phase 3 by October.

‘Nine out of 10 vaccines fail in the final phase of development, so it is not a done deal,’ Schuitemaker said. Phase 3 trials determine if a vaccine offers sufficient protection.

The Dutch government is part of a group of EU countries which have pre-ordered three million vaccines from AstraZeneca, which hopes to have its first vaccines ready by the end of this year.