Quantitative analysis of SARS-CoV-2 RNA in wastewater and evaluation of sampling frequency during the downward period of a COVID-19 wave in Japan

Tomohiro Kuroita; Akimasa Yoshimura; Ryo Iwamoto; Hiroki Ando; Satoshi Okabe; Masaaki Kitajima

doi:10.1016/j.scitotenv.2023.166526

Quantitative analysis of SARS-CoV-2 RNA in wastewater and evaluation of sampling frequency during the downward period of a COVID-19 wave in Japan

Sci Total Environ. 2024 Jan 1:906:166526. doi: 10.1016/j.scitotenv.2023.166526. Epub 2023 Aug 28.

Authors

Tomohiro Kuroita¹, Akimasa Yoshimura², Ryo Iwamoto¹, Hiroki Ando³, Satoshi Okabe³, Masaaki Kitajima⁴

Affiliations

¹ AdvanSentinel Inc., 3-1-8, Doshomachi, Chuo-ku, Osaka 541-0045, Japan; Shionogi & Co., Ltd., 3-1-8, Doshomachi, Chuo-ku, Osaka 541-0045, Japan.
² Shionogi & Co., Ltd., 3-1-8, Doshomachi, Chuo-ku, Osaka 541-0045, Japan.
³ Division of Environmental Engineering, Faculty of Engineering, Hokkaido University, North 13 West 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan.
⁴ Division of Environmental Engineering, Faculty of Engineering, Hokkaido University, North 13 West 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan. Electronic address: mkitajima@eng.hokudai.ac.jp.

PMID: 37647962
DOI: 10.1016/j.scitotenv.2023.166526

Abstract

Wastewater-based epidemiology (WBE) is a practical approach for detecting the presence of SARS-CoV-2 infections and assessing the epidemic trend of the coronavirus disease 2019 (COVID-19). The purpose of this study was to evaluate the minimum sampling frequency required to properly identify the COVID-19 trend during the downward epidemic period when using a highly sensitive RNA detection method. WBE was conducted using the Efficient and Practical virus Identification System with ENhanced Sensitivity for Solids (EPISENS-S), a highly sensitive SARS-CoV-2 RNA detection method, at nine neighboring wastewater treatment plants (WWTPs). These WWTPs were in the same prefecture in Japan, and they had different sewer types, sampling methods, and sampling frequencies. The overall detection rate of SARS-CoV-2 RNA was 97.8 % during the entire study period when the geometric means of new COVID-19 cases per 100,000 inhabitants were between 3.3 and 7.7 in each WWTP. The maximum SARS-CoV-2 RNA concentration in wastewater was 2.14 × 10⁴ copies/L, which corresponded to pepper mild mottle virus (PMMoV)-normalized concentrations of 6.54 × 10^-3. We evaluated the effect of sampling frequencies on the probability of a significant correlation with the number of newly reported COVID-19 cases by hypothetically reducing the sampling frequency in the same dataset. When the wastewater sampling frequency occurred 5, 3, 2, and 1 times per week, these results exhibited significant correlations of 100 % (5/5), 89 % (8/9), 85 % (23/27), and 48 % (13/27), respectively. To achieve significant correlation with a high probability of over 85 %, a minimum sampling frequency of twice per week is required, even if sampling methods and sewer types are different. WBE using the EPISENS-S method and a sampling frequency of more than twice a week can be used to properly monitor COVID-19 wave epidemic trends, even during downward periods.

Keywords: COVID-19; EPISENS-S; Public health; SARS-CoV-2; Wastewater-based epidemiology; qPCR.

MeSH terms

COVID-19* / epidemiology
Humans
Japan / epidemiology
RNA, Viral
SARS-CoV-2 / genetics
Wastewater

Substances

RNA, Viral
Wastewater