Yarmouth Covid Wastewater Testing Results - April 13, 2022
April 13th, 2022
Summary:
Yarmouth began a new wastewater testing program with the U.S. CDC on February 10, 2022. Data from that new program, which uses a new laboratory for testing, continues to show a lower—but persistent—level of the COVID-19 virus in the community. We continue to urge caution particularly in large group settings.
Details:
The new U.S. CDC funded wastewater testing program began in Yarmouth on February 10, 2022. Since then, Yarmouth has received the results for 12 wastewater samples, which are shown in Figure 1 below. The results from the last 6 months of the Yarmouth Community wastewater testing program (August 26, 2021 – February 22, 2022) are also shown in Figure 1.
Figure 1. Results of wastewater testing for SARS-CoV-2 for Yarmouth, Maine, from August 26, 2021 – April 5, 2022
At the end of the previous Yarmouth Community testing program and the beginning of the new US CDC program, two wastewater samples were tested by both programs. The Yarmouth Community sample on February 8 had a higher adjusted virus level than the US CDC sample on February 9. Both programs tested the February 22 sample, with a lower result for the Yarmouth Community program than the US CDC program:
The two programs use different methods for analyzing wastewater samples for SARS-CoV-2, including their methods for adjusting the results for wastewater flow (fecal content) and recovery during analysis. Thus, the differences in their results are not surprising and do not differ by more than a factor of 10.
The Yarmouth Wastewater Testing Team (YWTT) is evaluating the analysis and adjustment methods used by the US CDC wastewater testing program to understand their comparability to the methods used previously by the Yarmouth Community wastewater testing program.
The normalized virus levels for Yarmouth as reported by the US CDC program range from 18.4 copies/mL (18,400 copies/L) on March 15, to 185.0 copies/mL (185,000 copies/L) on February 22. The level on February 22 was much higher than any of the other values reported so far. (See table below.)
The results so far don’t show a consistent upward or downward trend. (See Table below and Figure 1 above.)
Figure 2 below shows (1) the results for the last 6 months of the Yarmouth Community wastewater testing program (August 26, 2021 – February 22, 2022); (2) the results for the first 8 weeks of the US CDC wastewater testing program for Yarmouth (February 10 – April 5, 2022); and (3) the weekly COVID-19 cases reported through April 8, 2022, by the Yarmouth schools for the 2021–2022 academic year. The number of school-reported COVID-19 cases has risen slightly to 9–19 cases per week since the end of the winter break (February 21–25), compared to 7 & 4 cases per week during the two weeks prior to the break.
Figure 2. Results of wastewater testing for SARS-CoV-2 for Yarmouth, Maine, from August 26, 2021 – April 5 and Yarmouth schools COVID-19 cases, September 4, 2021 – April 8, 2022
In light of the continuing lower—but still moderately positive—level of SARS-CoV-2 in Yarmouth's most recent wastewater results and the number of cases reported by the Yarmouth Schools in the past 6 weeks, we have kept the COVID-O-Meter at the Moderate level.
We still suggest that the Yarmouth Community continue to exercise caution:
Get vaccinated and boosted.
Consider wearing a mask in indoor public places.
Avoid crowded indoor spaces.
When indoors, good ventilation (air exchange) is important.
Test with a rapid antigen test when gathering with friends and family who have been out and about, or if you will be spending time with people at higher risk.
If you have COVID, leave isolation only after you have a negative rapid antigen test.