As coronavirus infections almost double in a week, initial tests for a University of Twente study suggest that it could be vital to wear face masks in bars and cafés, reports the AD.

Detlef Lohse, professor of the physics of fluids, is leading a study into how long droplets in the air hang and their possible role in infection. His initial trials suggest that they remain a danger for longer than previously thought, the paper reports.

‘They live for 30 to 40 times longer than thought in a model from the 1930s, which is the basis for the 1.5m distancing rules from the World Health Organization and the RIVM [Dutch public health institute],’ he reportedly said. ‘Facemasks are essential, for example in bars.’

Increasing concerns have emerged from scientists worldwide that the coronavirus is not only spread by droplets from coughs and sneezes but also via airborne transmission of tiny particles that could travel further.

On Tuesday, the RIVM announced that the weekly number of recorded infections in the Netherlands had increased from 534 on July 15 to 987 on July 21 – suggesting that each person infected is spreading the coronavirus to more than one other. Clusters of infections have been linked to events, for example, a meeting in a café in Hillegom after which 27 people tested positive, plus within families.

Eminent virologist Marion Koopmans told Nieuwsuur that she is concerned about the rapid rise in infections. ‘If we keep seeing this increase, then we need to take strong measures very quickly,’ she reportedly said.

The RIVM has not currently asked for stricter measures – such as mandatory face masks in shops, which France has introduced after infections rose – but warns people to keep their distance, wash hands frequently and get a test at any sign of complaints.

So far, 6136 people have died from the coronavirus in the Netherlands, half of them aged 83 or older.