Heatwaves Increase Emergency Admissions to Swiss Hospitals


The fact that heat threatens people's well-being comes as no surprise. The first scientific evaluation of the extent to which heatwaves influence emergency hospital admissions in Switzerland, however, has only been conducted recently. The summer of 2015—after 2003 the second hottest summer in Switzerland since temperature observation—caused more than 2,700 additional emergency admissions to Swiss hospitals. The most frequent causes were infectious diseases and diseases of the genitourinary system, as well as influenza and pneumonia. The study was published in the peer-reviewed journal Environmental Health on 15 August 2019.

The summer of 2015 caused more than 2,700 additional emergency admissions to Swiss hospitals.

Numerous studies have shown that heat increases mortality rates.1,2  In Switzerland, for example, the hot summer of 2015 caused around 800 additional deaths.3 Only a few studies, however, have investigated the effects of heatwaves on morbidity and hospital admissions. Researchers from the Swiss Tropical and Public Health Institute (Swiss TPH) recently conducted a detailed analysis of emergency hospital admissions in Switzerland during the three heatwaves between June and August 2015 in a study commissioned by the Federal Office for the Environment (FOEN).

First heatwave has the worst impact

The study, which was published today in the peer-reviewed journal Environmental Health, reveals that the heatwave of 2015 resulted in over 2,700 additional emergency hospital admissions. The most vulnerable populations are the elderly and residents of Switzerland’s warmest regions: Ticino and Lake Geneva. "The data from this and other studies reveal that the first heatwave of a summer has a pronounced impact on cases of death and disease," said Martina Ragettli, scientist at Swiss TPH and main author of the study. "The effect is exacerbated if the heatwave takes place in early summer.”

The most common causes of the additional emergency hospital admissions were infectious diseases, diseases of the genitourinary system and diseases of the digestive system, as well as influenza and pneumonia. "These causes are surprising since it is cardiovascular and respiratory diseases which play leading roles in heat-related deaths," says Ragettli. This indicates that the faster spread of viruses and bacteria at warmer temperatures may play an important role in terms of hospital admissions.

The study used data on emergency admissions to Swiss hospitals between 2005 and 2015 provided by the Federal Statistical Office (Medical Statistics of Hospitals). Statistical methods were utilised to estimate how many emergency hospital admissions were to be expected in the summer of 2015. Excess emergency hospital admissions were then estimated for total causes and for different disease categories by comparing observed and expected cases.  

Heat-health action plans prevent illness

The study authors recommend that the cantonal heat-health action plans be expanded in line with the study’s findings, including issuing advice on infectious and parasitic diseases. Studies in Switzerland show that cantonal heat-health action plans play an important role in preventing heat-related deaths during heatwaves.4  Even measures that are relatively easy to implement have a positive impact on the health of the population.

Climate change and health

Climate change and its detrimental effects on plants, animals and humans are a central challenge for sustainable development. For this reason, the United Nations urges immediate action to combat climate change and its effects within the framework of the Sustainable Development Goals (SDGs).

The Swiss TPH Winter Symposium, to be held from 5 to 6 December 2019 in Basel, Switzerland, will focus on climate change and health with emphasis on potential adaptation strategies to mitigate health risks.


1 Grize L et al. (2005). Heatwave 2003 and mortality in Switzerland. Swiss Medical Weekly, 135.13-14: 200–205.
2 Ragettli MS, Vicedo-Cabrera AM, Schindler C, Röösli M (2017). Exploring the association between heat and mortality in Switzerland between 1995 and 2013. Environmental Research, 158: 703–709.
3 Vicedo-Cabrera AM, Ragettli MS, Schindler C, Röösli M (2016) Excess mortality during the warm summer of 2015 in Switzerland. Swiss Medical Weekly, 146. w14379. ISSN 1424-7860
4 Ragettli MS, Röösli M (2019). Hitzeaktionspläne zur Prävention von hitzebedingten Todesfällen—Erfahrungen aus der Schweiz. Bundesgesundheitsblatt-Gesundheitsforschung-Gesundheitsschutz, 62: 605–611.