👉 H1N9 is a highly contagious respiratory illness caused by the influenza virus that originated in Mexico. It primarily affects children and adults, particularly those with weakened immune systems or who are immunocompromised, due to its ability to spread rapidly through droplets from coughing or sneezing. Symptoms typically include fever, sore throat, runny nose, and coughing, often accompanied by fatigue, body aches, and difficulty breathing. Treatment options vary depending on the severity of the illness.