Coronavirus levels have risen sharply in wastewater across the country, suggesting infections are continuing to rise over the summer.
Virus detection in sewage nationwide reached “high” levels for the first time this summer, according to estimates released Friday by the U.S. Centers for Disease Control and Prevention. The agency reports that COVID-19 is spreading or may be spreading in 44 states and the nation’s capital.
According to CDC data for the week ending July 6, coronavirus levels in California’s wastewater were “very high” for the first time since the start of winter. The other states are Arkansas, Florida, Maryland, Nevada, Oregon and Texas. Nineteen other states, covering regions across the country, also have high levels of coronavirus in their sewage.
It is estimated that coronavirus levels in California wastewater are significantly higher than last summer. In Northern California, two of the largest wastewater treatment plants in San Jose and Palo Alto, covering Santa Clara County (the region’s most populous county), reported high levels of viruses in their wastewater.
Additionally, the rate of positive coronavirus tests in California is nearly at its peak last summer. In the week ending July 8, 13% of reported tests were positive; the growth rate for the same period a month ago was 4.8%. The latest positive test rate nearly exceeds last summer’s peak of 13.1% in late August and early September.
In Los Angeles County, the most populous county in the United States, coronavirus levels in wastewater have risen significantly.
In addition, the Los Angeles County Department of Public Health said in a statement to The Times, “We are seeing an increase in COVID-19 cases, emergency room visits and hospitalizations.” “It’s too early to tell whether there will be larger waves this summer compared to last summer.”
In the 10 days ending June 29, the latest information available, coronavirus levels in Los Angeles County wastewater were 27% of last winter’s peak, according to the health department. This is a significant increase from the previous comparable period ended June 22 and is 17% of last year’s winter peak.
The county has also seen a significant increase in COVID-19 cases. There were an average of 307 new cases per day in the week ending July 7, up from 121 per day a month ago. The peak last summer was the week ending August 26, when daily cases averaged 571.
Officially reported cases are certainly an undercount because they only reflect the results of tests done at health facilities, not home tests. Additionally, fewer people are getting tested for coronavirus when they are sick. But measuring the number of cases is still useful for assessing overall trends.
The share of coronavirus-related emergency room visits has also increased in Los Angeles County. In the week ending July 7, 2.5% of emergency room visits were coronavirus-related; a month ago, that number was 1.5%. There was a spike last summer in the week ending Aug. 27, when 5.1% of emergency room visits were related to the coronavirus.
The mid-year increase in COVID-19 cases began in May, arriving earlier than normal. Previous mid-year surges in cases and hospitalizations in Los Angeles County began in early July in 2021 and 2023, but began in early May in 2022.
Cases at Kaiser Permanente facilities in Southern California continue to rise, officials said, with most of them among outpatients.
“The numbers are still rising slowly, slowly,” said Dr. Elizabeth Hudson, Kaiser’s Southern California infectious disease regional chief. “We’ll have to see where that goes now that we’re past the Fourth of July and that’s usually when we start to see more growth if we want to see that.”
Health officials across the country are closely watching the rise in infections. The New York City Department of Health and Mental Hygiene on Tuesday urged residents to consider wearing masks, especially in crowded indoor settings where cases are rising, especially in high-risk groups. “Wear a mask, New York!” the agency said in a social media post that included an illustration of a passenger wearing a mask on public transportation.
The rise in coronavirus infections comes amid a rise in a new subvariant called FLiRT, which is estimated to be 20% more contagious than the dominant winter variant. In the two weeks ending July 6, an estimated 70.5% of the country’s coronavirus samples were of the FLiRT subvariant – formally known as KP.3, KP.2 and KP.1.1. This is up from 54.9% a month ago.
The CDC has identified no states where COVID-19 cases are declining or likely to decline over the summer. Three states—Hawaii, New Mexico and Oregon—have either stable or uncertain trends in COVID-19 cases, according to the Centers for Disease Control and Prevention. There are no estimates available for Missouri, Wisconsin or Wyoming.
