SARS-CoV-2 Wastewater Presence at Highest Levels Since January as COVID-19 Cases Increase
Though hospitalizations and test positivity remain at modest levels, wastewater analysis indicates high circulation of SARS-CoV-2, especially in western states.
As we approach the fall and winter seasons when students are returning to school and gatherings are moving indoors, viral infections are poised to surge. Even before these seasons begin, however, COVID-19 rates are increasing across the country, according to viral SARS-CoV-2 wastewater activity data provided by the CDC.1
COVID-19 levels are high nationally according to wastewater data. Image credit: © Corona Borealis | stock.adobe.com
In the period from September 1 to September 7, wastewater levels were high or very high in 37 states, including populous ones such as California, Florida, and Texas. Regionally, the highest incidence of SARS-CoV-2 in wastewater is currently in the West (10.41), followed by the Midwest (8.42), South (7.96), and Northeast (3.79).2
It is important to note that 4 of the states had limited reporting coverage, while 3 states had no data reported. However, SARS-CoV-2 presence in wastewater is at its highest level nationally since January 2024.2
Variants of SARS-CoV-2 continue to drive surges in viral infection. The KP.3.1.1 strain, part of the Omicron family, remains the dominant variant in circulation, comprising 32% of all SARS-CoV-2 wastewater samples. This is followed by KP.3 (13%), JN.1 (12%) and LB.1 (12%).3
As of August 19, KP.3.1.1 was the only major variant increasing in proportion nationally. According to the CDC’s monitoring of variant proportions, at the conclusion of the 2-week period ending September 14, KP.3.1.1 had a 52% share of all the strains currently circulating nationally.4,5
Wastewater monitoring is a mechanism utilized by the CDC to detect increasing cases of infectious diseases early. When people with certain infections shed bacteria after using the bathroom or washing their hands, these pieces of the virus travel through the sewage system. Experts test wastewater samples before it is treated to detect different infections circulating in an area.6
New COVID-19 vaccines were granted emergency use authorization by the FDA in August for the 2024-2025 season, with a new monovalent component that corresponds to KP.2, a strain of the Omicron variant. Given the increasing presence of KP variants of SARS-CoV-2, it will be important for those recommended to be vaccinated to do so, especially as immunity from past vaccinations wanes.7
Of course, with any updates or novel vaccination, misinformation and mistrust will abound. However, experts have assured the public that COVID-19 vaccines are, and have remained, safe and effective.8
“COVID-19 vaccines have accumulated a very large safety experience since 2020-2021, and they continue to be extremely safe and effective,” Robert Walker, senior vice president, chief medical officer, and interim head of research and development at Novavax, said in an interview. “I think most people should feel confident in the performance of these vaccines and recognizing that they are probably among the safest interventions that are available today.”8
The importance of receiving an updated vaccination, even for individuals who were previously vaccinated, cannot be overstated. As aforementioned, immunity from prior vaccinations wanes after some time. Additionally, as new strains become dominant in viral circulation, protection from an older vaccine that was engineered for different strains will not offer broad protection in the present.8
“The main reason to get vaccinated this season is so that you have received the best possible match to the strains that you may otherwise are likely to be infected with, and the only way to do that is to get the updated formulation,” Walker explained.8
