Doctors are warning of a rise in contagious viruses as children return to school this fall. The latest COVID variant caused a late summer spike and doctors aren't exactly sure why."It took us by surprise the number of cases that we've had and now we're having schools come back in and various other things," said Dr. Andy Pekosz, a virologist and professor at the Johns Hopkins Bloomberg School of Public Health.And it's not just COVID, doctors say other viral diseases, like RSV or the flu, could soon pick up. "It's very difficult just based on symptoms to tell the difference between RSV, flu and COVID," Pekosz said.Doctors note that symptoms, like fatigue and fever, overlap, making it difficult to distinguish between the viruses without proper testing. They recommend contacting a healthcare provider for a diagnosis or buying your own tests."It's always a good idea to maybe stock up on some tests so you can actually get a definitive idea of what your child is infected with if they come home with respiratory symptoms," Pekosz said.Experts also suggest using personal protective equipment, such as masks, and practicing social distancing to help prevent the spread and stress the importance of staying home when sick, regardless of the illness."Those behavior changes do result in reduced spread of the virus and can be very helpful for people particularly in those high risk groups," Pekosz said.The FDA recently approved an updated version of the COVID vaccine for the latest variants, which will be available soon and can be taken along with the flu vaccine. The RSV vaccine is currently available for older and at-risk adults, as well as pregnant people.Also this month, the Biden administration plans to restart its free COVID test-by-mail program. Orders can be made at COVIDtests.gov.