A summer wave of COVID-19 has arrived in the U.S.

(CNN) – COVID-19 levels have been rising in the United States for weeks as new variants drive what’s become an annual summer surge.COVID-19 surveillance has been scaled back significantly since the U.S. public health emergency ended more than a year ago – individual cases are no longer counted, and severe outcomes are based on representative samples of the population – but the data that is available is showing a consistent upward trend.Related Stories Infections are probably growing in at least 38 states, according to data from the U.S. Centers for Disease Control and Prevention. Wastewater surveillance suggests that viral activity is still relatively low, but hospitalizations and deaths are also ticking up.COVID-19 levels are especially high in the West, where viral levels are back to what they were in February, and in the South, according to the CDC.“The virus tends to replicate well and to stay alive in an environment with warm and moist conditions. That fits with what we’re seeing,” said Dr. Robert Hopkins, medical director of the National Foundation for Infectious Diseases, a nonprofit public health organization. “The South and the West are steamy and hot right now.”The summer bump has become a familiar seasonal pattern, but experts...