Analyses of samples from wastewater catchment areas around the country have yielded results that are in keeping with high incidence rates of Covid-19 currently seen throughout Ireland, according to the Health Protection Surveillance Centre (HPSC).

The first weekly report of the national SARS-CoV-2 (Covid19) Wastewater Surveillance Programme (NWSP) has been published, and reveals that of 68 water samples analysed, SARS-CoV-2 – the virus that causes Covid-19 – was detected in 67.

The NWSP can act as an early-warning system for detection of the virus.

The approximate location of wastewater catchment areas and results for SARS-CoV-2 detections during week 33. Image source: Health Protection Surveillance Centre

These 68 wastewater catchment areas cover 80% of the population connected to public wastewater-treatment facilities.

One sample from the Shanganagh catchment area had not been received at the time of publishing the report.

The samples referred to above correspond to week 33 of the surveillance programme, and show that the number of catchment areas now included in the NWSP has increased from just 13 back in week 23.

Samples from 68 wastewater catchment areas across Ireland are now taken and analysed on a weekly basis.

The wastewater catchment area of Ringsend in Dublin is sampled twice a week due to the size of the population it captures.

People with Covid-19 can shed the virus in their stool, which can then be detected in wastewater.

This makes environmental surveillance of wastewater a feasible means to monitor the circulation of SARS-CoV-2 in the population.

The NWSP is a partnership comprised of Irish Water, the National Virus Reference Laboratory, University College Dublin, the HSE Health Protection Surveillance Centre and Health Intelligence Unit.