State and federal data show high levels of respiratory illnesses. Here's what to know about the illnesses circulating this winter, their symptoms and how to prevent them.

Influenza A, COVID-19 and norovirus (stomach flu) are on the rise, according to the Centers for Disease Control and Prevention. But there's a fourth "bug" the public should be aware of: respiratory syncytial virus. RSV causes cold-like symptoms and affects the breathing passages and lungs.

Public health advice for HMPV is similar to that for flu, said John Tregoning, professor in vaccine immunology at Imperial College London. "Protecting yourself by being in well-ventilated (spaces), covering your mouth when you cough (and) washing your hands will all help," he said.

RSV and norovirus are making the rounds in the aftermath of holiday gatherings. KDKA-TV's Shelley Bortz shares the latest details.

The annual surge of respiratory viruses — flu, COVID-19 and RSV — is in full swing, straining health systems and sparking concerns across the city. With flu cases spiking by 70% in recent weeks and all three viruses actively circulating, health officials have urged residents to take precautions to protect themselves and vulnerable populations.