News that 9% of those testing positive for coronavirus last week were fully vaccinated is not surprising but does show that everyone should remain cautious about catching the virus, Dutch epidemiologists say.

In particular, the more infectious Delta variant of the virus has been passed on to people who have been fully vaccinated, public health institute RIVM said on Monday. Some 77% of last week’s new patients had not been vaccinated at all but the rest had had one or two vaccine doses.

‘In the beginning we thought that you could not pass on the virus after you have been vaccinated, but that does not appear to be completely the case with the Delta variant,’ clinical virologist Matthijs Welkers from Amsterdam’s UMC medical centre told the Volkskrant.

‘We have seem people who have been infected, were then vaccinated twice and are now testing positive,’ he said.

Hospitals are also noticing that fully vaccinated members of staff are picking up the virus, although most have little in the way of symptoms, the paper said.

Marion Koopmans, a member of the government’s Outbreak Management Team advisory group, said the news that people who had been vaccinated had caught coronavirus is not a surprise because vaccines do not offer full protection. The protection level is ‘a little less than it was, but there is no reason to panic,’ she told NOS radio.

Trials

Clinical trials have shown that the Pfizer and Moderna vaccines reduce the chance of an infection by 95% while AstraZeneca and Janssen reduce the likelihood of picking up coronavirus by 70%.

‘The Delta variant has more virus particles and that means you need to be more careful, even if you have been vaccinated,’ Bert Niesters of Utrecht’s UMCG medical centre said.

The Delta variant also has a shorter incubation period so it is a question of the immune system getting going quickly enough, epidemiologist Amrish Baidjoe told broadcaster NOS.

Basic rules

Both Niesters and Baidjoe say that the basic rules, such as keeping 1.5 metres distance and testing if you have symptoms should apply to people who have been vaccinated as well. And Baidjoe told broadcaster NOS he would like to see face masks remain compulsory in high risk settings, such as in nursing homes.

‘We have to be realistic about what vaccines can and cannot do,’ Baidjoe said. ‘Vaccines are and remain our most important weapon, but they are not a silver bullet. They do allow us to take less strict measures, however, so it is important that we keep vaccinating people.’

Vaccination rate

According to the government’s coronavirus dashboard, over 19 million vaccine doses have been given in the Netherlands so far, and the RIVM said on Tuesday that 87% of people over the age of 65 are now fully vaccinated, as are 65% of those aged 45 to 64.

However, the vaccination rate remains lower in some cities and in parts of the Dutch Bible belt, the RIVM said.