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).
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Geographical distribution
Viral load in wastewater, Switzerland and Liechtenstein, 07.02.2022 to 29.05.2023
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
0,9%
−5,0
AG
Baden
AG Baden
59 560
0,8%
−8,6
AG
Bremgarten
AG Bremgarten
22 613
0,5%
−4,2
AG
Kaisten
AG Kaisten
25 354
0,4%
−0,1
AI
Appenzell (Boedeli)
AI Appenzell (Boedeli)
11 877
1,5%
−0,2
BE
Grindelwald
BE Grindelwald
4153
24,7%
−5,8
BE
Laupen
BE Laupen
62 000
7,4%
1,2
BE
Region Bern
BE Region Bern
224 557
0,4%
−2,4
BE
Thunersee
BE Thunersee
124 550
3,4%
1,0
BL
Birs
BL Birs
83 312
1,5%
−0,4
BS
Basel
BS Basel
273 075
12,6%
3,1
FR
Fribourg (Aele)
FR Fribourg (Aele)
44 211
0,5%
−4,9
GE
Aire
GE Aire
451 771
6,9%
−5,4
GL
Glarnerland
GL Glarnerland
49 644
22,3%
−11,5
GR
Chur
GR Chur
55 000
4,6%
−0,4
GR
Davos (Gadenstatt)
GR Davos (Gadenstatt)
9706
6,6%
2,6
GR
S-chanf (Oberengadin)
GR S-chanf (Oberengadin)
15 056
12,9%
−11,2
GR
Schluein (Gruob)
GR Schluein (Gruob)
7823
1,6%
−8,0
JU
Delemont (Sede)
JU Delemont (Sede)
36 484
0,5%
−1,2
JU
Porrentruy (Sepe)
JU Porrentruy (Sepe)
16 500
6,4%
1,0
LU
Buholz (Real)
LU Buholz (Real)
183 511
12,0%
1,9
NE
Neuchatel
NE Neuchatel
40 697
10,8%
2,6
NW
Stans (Rotzwinkel)
NW Stans (Rotzwinkel)
21 214
52,8%
22,3
OW
Alpnach (Sarneraatal)
OW Alpnach (Sarneraatal)
30 657
8,9%
−17,2
SG
Altenrhein
SG Altenrhein
64 000
8,3%
3,6
SG
Flums (Seez)
SG Flums (Seez)
12 448
0,6%
−0,1
SG
Rapperswil-Jona
SG Rapperswil-Jona
28 168
1,6%
0,0
SH
Neuhausen A/Rhf. (Roeti)
SH Neuhausen A/Rhf. (Roeti)
56 967
1,0%
−0,6
SH
Ramsen (Bibertal-Hegau)
SH Ramsen (Bibertal-Hegau)
100 338
1,0%
−0,5
SO
Zuchwil (Soloth.-Emme)
SO Zuchwil (Soloth.-Emme)
95 793
5,7%
1,4
SZ
Schwyz
SZ Schwyz
31 164
26,9%
15,2
TG
Frauenfeld
TG Frauenfeld
36 369
2,9%
0,4
TI
Chiasso (Vacallo)
TI Chiasso (Vacallo)
26 638
5,7%
−2,3
TI
Locarno (Foce Maggia)
TI Locarno (Foce Maggia)
50 781
8,2%
2,6
TI
Lugano
TI Lugano
124 000
13,9%
2,3
UR
Altdorf
UR Altdorf
33 940
17,3%
7,8
VD
Lausanne (Vidy)
VD Lausanne (Vidy)
247 824
2,7%
−7,3
VS
Bagnes-Le Châble
VS Bagnes-Le Châble
7713
5,0%
3,7
VS
Brig-Glis (Briglina)
VS Brig-Glis (Briglina)
28 678
7,1%
−1,2
VS
Martigny
VS Martigny
39 643
4,9%
1,7
VS
Sierre/Noes
VS Sierre/Noes
32 480
2,9%
0,1
ZG
Cham (Schoenau)
ZG Cham (Schoenau)
146 942
16,1%
1,2
ZH
Bülach
ZH Bülach
35 612
6,1%
4,6
ZH
Dietikon (Limeco)
ZH Dietikon (Limeco)
83 367
9,9%
−3,7
ZH
Illnau-Effretikon
ZH Illnau-Effretikon
18 921
8,1%
−3,0
ZH
Werdhölzli
ZH Werdhölzli
471 000
17,1%
4,3
ZH
Winterthur
ZH Winterthur
140 403
8,6%
−2,3
Geographic distribution over time
View the development of the virus load in wastewater at various WWTPs in Switzerland and Liechtenstein.
Viral load in wastewater, Switzerland and Liechtenstein, 07.02.2022 to 29.05.2023
The graph shows the absolute and the relative viral load in per cent as a 7-day average in the wastewater treatment plants (WWTPs) in Switzerland and Liechtenstein and the difference in viral load compared with the previous week’s 7-day average in percentage points (pp). The 7-day relative share refers to the historical maximum values for each wastewater treatment plant. Vertical lines indicate changes in methodology. Shaded areas indicate data points that are below the limit of quantification (LoQ).
Flawil (Oberglatt), SG Population coverage: 30 378