Over half of US states reporting 'very high' COVID activity levels, CDC data shows

More than half of U.S. states are reporting "very high" levels of COVID activity as the virus continues to spread and increase in many parts of the country, according to the latest wastewater data from the Centers for Disease Control and Prevention.

At least 27 states are reporting "very high" levels and 17 states are reporting "high" levels of wastewater viral activity.

The western region continues to see the highest levels followed by the South, Midwest and Northeast, respectively.

Current levels are nearing but remain lower than what they were in the winter months, when there tends to be increased spread of respiratory illnesses.

Wastewater data comes with limitations in how well it represents spread in a community, but it may be the best data available, experts say.

"While wastewater is not a perfect measure, it's increasingly vital in filling the gaps left by the absence of comprehensive case reporting and hospitalization data," said Dr. John Brownstein, an epidemiologist and chief innovation officer at Boston Children's Hospital and an ABC News contributor.

Many national surveillance systems have diminished in scope since the national public health emergency ended , leaving authorities will limited resources to monitor how the virus is spreading.

"As traditional surveillance systems have dwindled, wastewater analysis has emerged as one of the most reliable tools we have to monitor COVID-19 activity in communities," Brownstein added.

Other limited COVID surveillance systems such as emergency department visits and test positivity are also on the rise, according to CDC data . Deaths from the virus remain relatively flat, especially compared to previous years.

Updated COVID vaccines are set to be available this fall, according to federal health authorities. The U.S. Food and Drug Administration recommended that vaccine manufacturers formulate shots based on the KP.2 strain, an offshoot of the omicron variant that is currently estimated to make up about 6% of cases.

Genetically similar variants, known as KP.3.1.1 and KP.3, currently make up almost half of estimated cases, CDC data shows .

The CDC has already recommended that everyone over the age of 6 months get an updated COVID vaccine this season. The recommendation will take effect as soon as the vaccines are made available, pending FDA authorization.

An expected delivery date for the updated COVID vaccines has not been shared yet, but in previous years the shot was made available in late August or September. Vaccine manufacturers have told ABC News they are ready to ship doses as soon as they receive the green light from the FDA.