Harvard researchers recently discovered that a prior case of pneumonia can be a strong indicator that you’ll have a more severe—or even deadly—case if infected with COVID. In their new study, published in the journal NPJ Digital Medicine on Feb. 4, they pulled data from the medical records of nearly 17,000 COVID patients. Their research showed that after age, pneumonia was the second-greatest risk factor for death from COVID. Out of those who died from COVID, nearly 49 percent had a history of pneumonia. “A history of pneumonia, which is rarely asked in typical epidemiology studies, was one of the most important risk factors for predicting COVID-19 mortality,” the researchers stated in their study. And for more ways to reduce your risk, find out why These 3 Vitamins Could Save You From Severe COVID, Study Finds. Pneumonia is a very common illness in the U.S. According to the Centers for Disease Control and Prevention (CDC), nearly 1.3 million Americans were diagnosed with pneumonia in 2017. The agency says that while most people who come down with pneumonia in the country are adults, this lung infection can affect people of all ages. And for more coronavirus concerns, know that Dr. Fauci Just Issued This New Chilling Warning About COVID. According to Health, many people never even realize they have had a case of pneumonia—especially if they had a mild case. Zachary Strasser, MD, one of the study authors and a Harvard postdoctoral fellow at Massachusetts General, told Bloomberg News that it’s even common for cases of chronic pneumonia to go undiagnosed.ae0fcc31ae342fd3a1346ebb1f342fcb According to the American Lung Association, this may be due to the fact that “pneumonia can be difficult to diagnose because the symptoms are so variable, and are often very similar to those seen in a cold or influenza.” The symptoms of pneumonia include cough, fever, shortness of breath, chest pain, loss of appetite, fatigue, nausea, and confusion. And for more up-to-date COVID news, sign up for our daily newsletter. The CDC has created a list of medical conditions that put you at increased risk of severe illness or death from COVID, but pneumonia is not one of them. However, as the Harvard researchers note, a previous pneumonia case could actually be an indicator of an underlying condition that is included in the list of risk factors. In fact, the CDC says you are more likely to get pneumonia if you smoke or have underlying medical conditions like diabetes or heart disease. And smoking, diabetes, and heart disease are all listed by the CDC as conditions that put you at increased risk of severe COVID. And for more from this agency, find out why The CDC Warns Against Using These 6 Face Masks.