Swiss health experts sign letter wary of herd immunity claims

The number of new daily Covid-19 infections has risen sharply in Switzerland in the last week. Keystone / Laurent Gillieron

Amid rising Covid-19 cases in Switzerland, five experts have signed a letter in the Lancet warning that a pandemic management strategy relying on herd immunity is flawed.

The “John Snow Memorandum”, named after a British physician considered a founder of modern epidemiology, was published in the LancetExternal link scientific journal on Wednesday. It is the work of a group of international researchers with expertise across public health fields, who “felt moved to deliver a clear and simple message about how best to manage the Covid-19 pandemic”.

More than 50 international researchers have signed, including five from Swiss universities: Christian Althaus from the University of Bern, Isabella Eckerle at the University of Geneva, Jacques Fellay at the University Hospital in Lausanne, Emma Hodcroft at the University of Basel, and Ilona Kickbusch from the Graduate Institute of International and Development Studies in Geneva.

The letter argues that as cases rise, reaching more than 2,800 new daily infections in Switzerland on Wednesday, there is a need for clear communication about the risks posed by Covid-19 and effective strategies to combat them.

The arrival of a second wave has led to renewed interest in the concept of so-called herd immunity, which would allow large uncontrolled outbreaks in the low-risk population while protecting the most vulnerable.

“This is a dangerous fallacy unsupported by scientific evidence,” states the letter. According to the researchers, this raises the risks of significant morbidity and mortality, and could overwhelm healthcare systems.

They note that there is no evidence for lasting protective immunity to Covid-19 following natural infection and there remains a lack of understanding of who might suffer from long-term Covid-19 effects.

There is growing concern about rising cases across much of Switzerland. In an interview in the German-language newspaper Tages-Anzeiger, former Covid-19 taskforce head and epidemiologist Matthias Egger called on the government and cantons to act quickly to prevent another lockdown.

Swiss President Simonetta Sommaruga is expected to meet cantonal authorities on Thursday to discuss the way forward.