People with weakened immune systems may need three or four vaccine doses to give them sufficient protection from coronavirus, experts have said.

Hospitals are studying the impact of the vaccine on people whose immune response is lower because of genetic conditions, illnesses such as leukaemia or as a result of medicines they have to take following a transplant.

Bram Goorhuis, co-ordinator of Amsterdam UMC’s coronavirus department, said around 50,000 people in the Netherlands may need further shots of the vaccine to boost their resistance to the virus.

‘We want to make sure we give these patients good protection too,’ Goorhuis told AD.nl. ‘It could work if we give them more vaccines.’

France has already decided to offer third doses to patients with reduced immunity after research showed a first jab gave them only 17% protection and two vaccines raised the level to 45%.

The Dutch health ministry has so far not responded to questions from Dutchnews.nl about whether it plans to introduce third vaccinations.

Currently eight studies are taking place around the country into the effect of the vaccine on patients with low or compromised immune response. One study in Groningen is looking at the effect on 500 cancer patients who are undergoing chemotherapy or immunotherapy.

‘We are hoping to find out which patients don’t develop a good response. That could depend on their age, the type cancer or the type of therapy,’ said Liesbeth de Vries, professor of medical oncology at Groningen UMC.