Monitoring wastewater can help communities detect and prepare for increasing cases of COVID-19 in a timely manner (https://www.cdc.gov/nwss/how-wws-works/index.html#print):
- People with COVID-19 can shed the virus in their feces (poop), even if they don’t have symptoms.
- The virus in poop is flushed down the toilet and travels through the sewage system.
- Before wastewater is treated, wastewater technicians take samples to get information about the virus.
- Laboratories test for the virus and measure virus levels in the wastewater.
- Public health officials use wastewater data to better understand COVID-19 trends in communities and make decisions, such as where to have mobile testing and vaccination sites.
Wastewater surveillance data are used to:
- Monitor for the presence of infection within a community.
- Tracking trends in infection within a community.
It also can be used to screen for infection at a targeted site, such as a building or facility, to determine whether additional individual-based testing or mitigation measures need to be implemented (https://www.cdc.gov/nwss/interpretation/index.html).
As shown below, wastewater SARS-CoV-2 tracks case data nationally, up to the end of January 2022 when home test kits became widely available. Since that time, case data appears to underestimate the number of cases (see lower right-hand side graph).
The top graph below are the wastewater concentrations for the City of Brookings. The slide below that are the case data for Brookings Country (the box represents a similar time period). Wastewater SARS-CoV-2 levels were not being measured during any of the large peaks in Brookings cases.
Another advantage of monitoring wastewater is that the samples can be sequenced to identify which SARS-CoV-2 variants are present. Below are the sequencing data for the City of Brookings up to the end of January 2023. One can see that the BA.5 variant was the most common variant identified until the fall of 2022. The last couple of weeks of data for the month of January shows an increase in the presence of the XBB variant.
Thanks again to the Water Department at Brookings Municipal Utilities and the Drs. McFarland and Huber at USD for the availability of these data.
Just a reminder of the differences between community levels and community transmission levels:
|Community Levels||Community Transmission Levels|
|Used to determine the impact of COVID on communities to determine which preventive actions to take.||Describes the amount of COVID spread. Healthcare facilities use to determine infection control interventions.|
|Based on: |
New cases/100,000 in last 7 days
COVID hospital admission/100,000 in last 7 days
Percentage of inpatient beds occupied by COVID patients
|Based on: |
New cases/100,000 in last 7 days
Percent test positivity during the last 7 days
Brookings County (low community level; high community transmission [% test positivity = 24% vs. 21% last week])
- Only 18% of people 18 years of age and older in Brookings County have received the updated bivalent booster (link to data here).
- 9,540 total cases: 15 new cases this week vs. 8 in the previous week. Of the new cases this past week:
- 13% were under 20 years of age (vs. 25% in previous week)
- 27% were 20-39 years (vs. 50% in previous week)
- 20% were 40-59 years (vs. 25% in previous week)
- 40% were 60 years or older (vs. 0% in previous week)
- 256 Brookings County residents have been hospitalized with COVID: 0 hospitalizations posted this past week compared to 1 in the previous week.
- Currently, the percentage of staffed beds that are COVID-occupied in the Sioux Empire region is 2.5% (compared to 2.7% last week), and 23.9% of the total hospital beds are available (compared to 25.5% last week).
- 67 Brookings County residents have died of COVID: 0 new deaths were reported this past week compared to 0 deaths in the previous week.
South Dakota (low community level; high community transmission [% test positivity = 20-24.9%+ vs. 25%+ last week])
- Only 21% of people 18 years of age and older in South Dakota have received the updated bivalent booster (link to data here).
- 280,525 cases: 643 new cases this week vs. 752 in the previous week. Of the new cases this past week
- 19% were under 20 years of age (vs. 14% in previous week)
- 22% were 20-39 years (vs. 25% in previous week)
- 21% were 40-59 years (vs. 24% in previous week)
- 37% were 60 years or older (vs. 37% in previous week)
- 12,650 South Dakota residents have been admitted to in-state hospitals with COVID: 31 were admitted this week vs. 37 last week. Of the new hospital admissions this past week:
- 3% were under 20 years of age (vs. 5% in previous week)
- 0% were 20-39 years (vs. 14% in previous week)
- 29% were 40-59 years (vs. 16% in previous week)
- 68% were 60 years or older (vs. 65% in previous week)
- 44 people are currently hospitalized vs. 44 last Wednesday (7 currently in the ICU vs. 3 last week).
- Currently, the percentage of staffed beds statewide that are COVID-occupied is 2.1% (compared to 2.1% last week), and 34.9% of the total hospital beds are available (compared to 36.2% last week).
- 3,200 South Dakotans have died from COVID: 4 new deaths reported this week vs. 10 in the previous week. Of the deaths this past week:
- 1 was 40-59 years
- 3 were 60 years or older
- 105.9 million cases: 322,138 new cases this week vs. 224,032 in the previous week
- 1.15 million total deaths: 2,629 deaths this week vs. 2,036 in the previous week
- 682.7 million cases: 993,132 cases this week vs. 889,1445 million in the previous week
- 6.82 million deaths: 8,038 deaths this week vs. 6,602 in the previous week
Take care of yourself and each other.