In his speech on Monday, Rutte said his government had ruled out two options: letting the virus spread unchecked, and locking down the country “for a year or even longer”.
Instead, the government settled on a third option dubbed “maximum control”.
He said “experts are telling us” that the Netherlands can slow the spread of the virus “while at the same time building group immunity in a controlled way”.
“Those who have had the virus are usually immune afterwards – just like in the old days with measles,” he said. “The larger the group that is immune, the less chance that the virus will jump to vulnerable elderly people and people with poor health. With group immunity you build, as it were, a protective wall around them.
“That is the principle. But we have to realise that it can take months or even longer to build up group immunity and during that time we need to shield people who are at greater risk as much as possible.”
The herd immunity concept has caused alarm among epidemiologists and immunologists.
William Hanage, a professor of the evolution and epidemiology of infectious disease at Harvard University, used a blistering opinion piece in The Guardian to warn “nobody should be under the illusion that this is something that can be dodged through somehow manipulating a virus that we are only beginning to understand”.
The World Health Organisation has said COVID-19 hasn’t been in the population long enough to understand how it operates and Australian experts have also cast doubt over the idea.
Britain’s Chief Scientific Advisor Sir Patrick Vallance last week said achieving herd immunity was “one of the key things we need to do” alongside lowering the caseload peak and spreading out infections over a long period.
Having so far resisted some of the more draconian social distancing measures enacted across Europe, British Prime Minister Boris Johnson on Monday abruptly changed course and unveiled a series of new measures designed to more aggressively suppress the virus.
Hours after that announcement, a team of Imperial College researchers released modelling that found a middle-of-the-road “mitigation” approach – that up until Monday, London time, had been pursued by the UK – would overwhelm hospitals “many times over”. The research is significant as the Imperial College team is advising Downing Street on how to respond to the crisis.
Mitigation focuses on slowing but not necessarily stopping epidemic spread, whereas suppression aims to reverse epidemic growth, reduce case numbers to low levels and maintain that situation indefinitely.
The modelling found that tackling the outbreak only through mitigation measures such as case isolation, household quarantine and social distancing for the elderly would exceed “surge limits” for general ward beds and intensive care beds “by at least eight-fold” even under their most optimistic modelling scenario.
“In addition, even if all patients were able to be treated, we predict there would still be in the order of 250,000 deaths in Great Britain, and 1.1 to 1.2 million in the United States.
“We therefore conclude that epidemic suppression is the only viable strategy at the current time.”
However the researchers warned the “social and economic effects of the measures which are needed to achieve this policy goal will be profound”.
The suppression measures would have to involve, at minimum, social distancing of the entire population, home isolation and quarantine, and potentially school and university closures.
“The major challenge of suppression is that this type of intensive intervention package – or something equivalently effective at reducing transmission – will need to be maintained until a vaccine becomes available (potentially 18 months or more) given that we predict that transmission will quickly rebound if interventions are relaxed,” the researchers said.
Johnson is expected to respond to the modelling’s release on Tuesday.
Bevan Shields is the Europe correspondent for The Sydney Morning Herald and The Age.