COVID-⁠19 Switzerland

Information on the current situation, as of 21 March 2023

The key figures will be published each Tuesday at 15:30.

Epidemiological course,Switzerland and Liechtenstein

Viral load in wastewater

The data published here are based on information obtained from the federal government's national wastewater monitoring system. Since January 2022, the national wastewater monitoring system of Switzerland and the Principality of Liechtenstein has determined the SARS-⁠CoV-⁠2 viral load in the wastewater of participating wastewater treatment plants (WWTP) at regular intervals.

Wastewater samples are collected from wastewater treatment plants three to six times per week. The absolute viral load (gene copies/day) is specified per 100,000 inhabitants. A dilution factor based on the wastewater treatment plant's flow volume is taken into account, for instance during dry periods. The relative viral load is the measured viral load (gene copies/day) as a proportion of the historically measured maximum value. The proportion of relative viral load is calculated by dividing the proportion of absolute viral load by the proportion of the historic maximum viral load value. The residential population comprises the catchment area of each wastewater treatment plant (WWTP). Seasonal fluctuations in the non-⁠permanent population, which influence the viral load particularly in busy tourist areas, are not included. Wastewater treatment plants (WWTP) no longer participating in the project will not be included when calculating the proportion of viral load per category. However, historical measurements will still be available when viewing the development over time.

Detailed information on the measuring methods and terminology can be found on the Eawag website. New findings may prompt adjustments to data calculations. In certain cases, modifications to the sampling process and/or lab methodologies reduce comparability with data previously obtained. This concerns the wastewater treatment facilities in Burgdorf (whose sampling scheme was modified with effect from 23 August 2022) as well as Aarau, Aarburg, Appenzell (Boedeli), Baden, Bremgarten, Brugg, Hallau (Klettau), Kaisten, Lenzburg, Neuhausen am Rheinfall (Roeti), Ramsen (Bibertal-⁠Hegau), Wohlen and Zofingen (whose lab methodologies were modified with effect from 30 October 2022).

The timeframe desired can be selected using the slider below the chart.

Geographical distribution

Viral load in wastewater, Switzerland and Liechtenstein, 07.02.2022 to 20.03.2023

The graph shows the relative viral load in per cent as a 7-⁠day average in the wastewater treatment plants (WWTPs) and the difference in viral load compared with the previous week in percentage points (pp) in Switzerland and Liechtenstein. The percentage point figure is used to compare percentages. The 7-⁠day relative share refers to the historical maximum values for each wastewater treatment plant.
Cant. Name Population coverage Relative viral load Difference to previous week
AG Aarau AG Aarau 78 255 17,1% −24,5
AG Baden AG Baden 59 560 36,5% −10,4
AG Bremgarten AG Bremgarten 22 613 8,4% −2,2
AG Kaisten AG Kaisten 25 354 2,3% 0,4
AI Appenzell (Boedeli) AI Appenzell (Boedeli) 11 877 11,7% −15,0
BE Grindelwald BE Grindelwald 4153 21,5% −18,4
BE Laupen BE Laupen 62 000 24,6% 10,2
BE Region Bern BE Region Bern 224 557 17,2% 6,5
BE Thunersee BE Thunersee 124 550 11,6% −1,9
BL Birs BL Birs 83 312 36,2% −63,7
BS Basel BS Basel 273 075 6,0% 1,1
FL Liechtenstein FL Liechtenstein 39 315 26,8% 6,0
FR Fribourg (Aele) FR Fribourg (Aele) 44 211 17,2% 3,7
GE Aire GE Aire 451 771 32,2% 9,1
GL Glarnerland GL Glarnerland 49 644 60,6% 6,5
GR Chur GR Chur 55 000 35,1% 11,4
GR Davos (Gadenstatt) GR Davos (Gadenstatt) 9706 51,9% −1,7
GR S-chanf (Oberengadin) GR S-chanf (Oberengadin) 15 056 48,4% −15,1
GR Schluein (Gruob) GR Schluein (Gruob) 7823 47,0% −21,8
JU Delemont (Sede) JU Delemont (Sede) 36 484 27,9% 13,8
JU Porrentruy (Sepe) JU Porrentruy (Sepe) 16 500 27,0% −0,6
LU Buholz (Real) LU Buholz (Real) 183 511 14,5% −13,1
NE Neuchatel NE Neuchatel 40 697 13,4% 5,4
NW Stans (Rotzwinkel) NW Stans (Rotzwinkel) 21 214 12,2% −19,5
OW Alpnach (Sarneraatal) OW Alpnach (Sarneraatal) 30 657 23,5% 9,0
SG Altenrhein SG Altenrhein 64 000 44,5% 21,0
SG Flums (Seez) SG Flums (Seez) 12 448 16,2% 2,0
SG Rapperswil-Jona SG Rapperswil-Jona 28 168 11,8% −0,3
SH Neuhausen A/Rhf. (Roeti) SH Neuhausen A/Rhf. (Roeti) 56 967 16,4% −7,8
SH Ramsen (Bibertal-Hegau) SH Ramsen (Bibertal-Hegau) 100 338 17,8% −23,9
SO Zuchwil (Soloth.-Emme) SO Zuchwil (Soloth.-Emme) 95 793 27,6% 3,4
SZ Schwyz SZ Schwyz 31 164 17,4% 4,8
TG Frauenfeld TG Frauenfeld 36 369 34,6% 6,0
TI Chiasso (Vacallo) TI Chiasso (Vacallo) 26 638 7,7% −12,6
TI Locarno (Foce Maggia) TI Locarno (Foce Maggia) 50 781 5,1% −20,1
TI Lugano TI Lugano 124 000 39,5% 4,0
UR Altdorf UR Altdorf 33 940 16,9% −9,0
VD Lausanne (Vidy) VD Lausanne (Vidy) 247 824 14,7% −2,9
VS Bagnes-Le Châble VS Bagnes-Le Châble 7713 62,5% −27,4
VS Brig-Glis (Briglina) VS Brig-Glis (Briglina) 28 678 34,2% −17,0
VS Martigny VS Martigny 39 643 12,9% 4,3
VS Sierre/Noes VS Sierre/Noes 32 480 47,0% 0,0
ZG Cham (Schoenau) ZG Cham (Schoenau) 146 942 16,3% −9,5
ZH Bülach ZH Bülach 35 612 38,5% 16,8
ZH Dietikon (Limeco) ZH Dietikon (Limeco) 83 367 65,8% 31,9
ZH Illnau-Effretikon ZH Illnau-Effretikon 18 921 61,1% 28,8
ZH Werdhölzli ZH Werdhölzli 471 000 30,4% −1,1
ZH Winterthur ZH Winterthur 140 403 50,4% 12,1
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Source: FOPH – Status: 21.03.2023, 08.00h
Geographic distribution over time

View the development of the virus load in wastewater at various WWTPs in Switzerland and Liechtenstein.

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Development over time

Viral load in wastewater, Switzerland and Liechtenstein, 07.02.2022 to 20.03.2023

The figure shows the 7-⁠day average absolute and relative viral load in percent in the wastewater treatment plants (WWTP) and the difference from the previous week's 7-⁠day average in percentage points (pp) in Switzerland and Liechtenstein. The relative proportion per 7-⁠day period refers to the historically measured maximum value per wastewater treatment plant.
Wetzikon (Flos), ZH Population coverage: 31 419
Participated until 31.12.2022
Measured
7-⁠⁠day average
No participation

Relative viral load

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Source: FOPH – Status: 21.03.2023, 08.00h