(CNN)Flu activity increased over the past week, squelching hopes of an early peak and leading at least 12 states to shut down some schools.
There have been as many as 11.4 million flu illnesses, 5.4 million medical visits and 136,000 flu hospitalizations between October 1, 2018 and January 19, 2019, according to the weekly flu report released Friday by the US Centers for Disease Control and Prevention.
During the week that ended January 19, the CDC reported three additional children had died due to flu-related causes, bringing the total number to 22 for the season. For adults, flu deaths are estimated based on pneumonia and other illnesses related to flu. The proportion of deaths attributed to pneumonia and flu was 7.2%, which is slightly higher than the usual threshold of 7.1% for this time of year, the CDC said, based on data from the National Center for Health Statistics.