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What the 1918 Flu Teaches Us About Surges

February 8/2021

U of T and Swiss scientists reach into history to find a possible roadmap for preventing new COVID-19 surges

Researchers from U of T’s Dalla Lana School of Public Health (DLSPH) and Swiss counterparts have shown that a hesitant and decentralized response to the Spanish Flu led to longer and stronger follow-up waves of the disease in the Swiss canton of Bern a century ago.

They point to a striking similarity in the way both diseases have ebbed and flowed based on similar public health decisions – and argue that public health officials can find valuable lessons from Swiss mistakes.

“It’s important to learn lessons from the past, with a third COVID-19 wave threatening due to virus mutations from England, South Africa and Brazil,” says study co-first author Dr. Peter Jüni, a professor of epidemiology at DLSPH’s Institute for Health Policy, Management and Evaluation. “Understanding where they went wrong could lead to officials and the public rethinking our response to subsequent waves of the pandemic.”

head shot of Prof. Peter Juni wearing blue button down shirt

Prof. Peter Jüni

Until now, the Spanish Flu was considered the largest public health catastrophe in Swiss history, causing 25,000 deaths in a population of 3.75 million. Jüni and a team of researchers in epidemiology, evolutionary medicine, history and geography found that officials relaxed restrictions after the summer wave, and didn’t reintroduce them immediately at the beginning of the autumn wave due to economic fears. This brought back worse surges in the small province (canton) of Bern.

Analyzing thousands of medical and other records using modern epidemiological models, the interdisciplinary team found the Spanish Flu spread differently in the canton of Bern depending on the region —  much like the COVID-19 autumn wave in Ontario. In the first wave in July and August 1918, authorities intervened relatively quickly, strongly and centrally, including restricting gatherings and closing schools. After the first wave subsided, the canton lifted all measures entirely in September 1918, which led to a resurgence of cases and a quick second wave.

But Swiss authorities stumbled in their response to the second wave, Jüni says. Fearing renewed economic consequences, canton leaders left the responsibility for renewed public health measures to the individual municipalities for several weeks.

“This hesitant and decentralized approach was fatal and contributed to the fact that the second wave became all the stronger and lasted longer, says Jüni, who is also a general internist and professor in the Faculty of Medicine and serves as scientific director of the Ontario COVID-19 Science Advisory Table.

By comparing case counts of both diseases, the team found that the second wave started in almost the same calendar week in both 1918 and 2020, and that the official response was strikingly similar.

“While there are still important differences between the two pandemics, the steadily increasing parallels between 1918 and 2020 are remarkable,” says co-first author Dr. Kaspar Staub, of the University of Zurich. “We see in the numbers that centralized and strong measures – similar to what we see today – were associated with a stronger slowdown of epidemic growth during the first wave as compared to the second wave.”

Adds Jüni: “Switzerland had one of the highest mortality rates in the western world during the COVID-19 autumn wave, which to date has been more than three times higher than in Ontario, despite much less socioeconomic inequity in Switzerland, much better occupational health and safety, and higher standards in long-term care homes.”

Jüni, who moved to Toronto from Switzerland five years ago, believes that the hesitant attitude is partly explained by an ongoing polarization between the scientific community and some of the elected Swiss politicians. “An ongoing collaboration and constructive discussions between science and politics, as is happening here in Ontario, is of paramount importance for all of us, especially when faced with the current challenges of the more transmissible UK variant and delays in vaccine delivery,” he says.

The team published their findings in the Annals of Internal Medicine on Feb. 8, 2021.