COVID-⁠19 Switzerland

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).

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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.

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Development over time

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).

Data only available for individual WWTP
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Epidemiological course,Vaud

Laboratory-⁠confirmed cases, VD

Laboratory-⁠confirmed hospitalisations, VD

Laboratory-⁠confirmed deaths, VD

Tests and share of positive tests, VD

Viral load in wastewater, VD

Virus variants, VD

Outpatient consultations, VD

Viral load in wastewater

Geographical distribution

Geographic distribution over time

Development over time