Lifestyle Health Experts Warn of Another Rise in U.S. COVID Cases as BA.2 Variant Spreads in Europe Wastewater samples — which can predict when COVID-19 infections will increase — show that U.S. cases are rising again By Julie Mazziotta Julie Mazziotta Twitter Julie Mazziotta is the Sports Editor at PEOPLE, covering everything from the NFL to tennis to Simone Biles and Tom Brady. She was previously an Associate Editor for the Health vertical for six years, and prior to joining PEOPLE worked at Health Magazine. When not covering professional athletes, Julie spends her time as a (very) amateur athlete, training for marathons, long bike trips and hikes. People Editorial Guidelines Published on March 15, 2022 11:37 AM Share Tweet Pin Email COVID-19 at-home test. Photo: Getty Images Experts are warning that the United States will soon see another spike in COVID-19 cases as wastewater samples in parts of the country show an increase in infections and the BA.2 subvariant spreads in Europe. Cases are climbing in the United Kingdom — up 48% in the last week — and in more than half of countries in the European Union. The change appears to be due to several causes: the BA.2 subvariant of omicron, which is even more transmissible; the removal of pandemic mitigation efforts like mask mandates; and waning immunity from vaccination or prior infection. Past COVID-19 surges hit Europe first before spreading to the U.S. about two weeks later, making their rise in cases a warning sign of what's to come, especially as nearly all of the U.S. moves towards a new post-pandemic life without mask mandates or vaccine requirements. "Without a doubt, opening up society and having people mingle indoors is clearly something that is a contributor, as well as overall waning immunity, which means we've really got to stay heads-up and keep our eye on the pattern here," Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told CNN. "So that's the reason why we're watching this very carefully." Pfizer CEO Says Fourth Dose of COVID Vaccine 'Is Necessary,' Working on Vaccine for 'All Variants' The U.S. is also starting to see an increase of COVID-19 in wastewater samples, a strong early predictor of when the virus is about to spike. Between Feb. 24 and March 10, the presence of COVID-19 increased by 100% or more in 37% of U.S. wastewater sites, according to the Centers for Disease Control's tracking system. With asymptomatic or untested people able to shed the virus, wastewater samples can capture a more accurate idea of how much COVID-19 is circulating in an area than testing positivity rates. The CDC's wastewater data shows a rise in COVID-19 in parts of Ohio, Florida, Wisconsin, Illinois and New York. RELATED VIDEO: 29-Year-Old Runner Shares Her Struggle with Long COVID: 'I'm a Different Person' Experts hope that while cases may rise — with more Americans vaccinated or recovered from recent COVID-19 infections — new infections will be mild and will not require hospitalization, preventing hospitals from being overwhelmed and avoiding a surge in deaths. Andy Slavitt, a former senior advisor on COVID-19 to the White House, said in a Twitter thread that this anticipated rise in cases means that anyone who hasn't had omicron and hasn't been boosted should do that now, and any kids who are not vaccinated should get it, "particularly now that schools don't require masking." "The virus will continue to mutate with unknown outcomes," Slavitt warned.