A pneumonia infection causes the air sacs in your lungs to fill with fluid, making it hard for you to breathe. Pneumonia symptoms can range from mild to life-threatening. Older adults and those with certain risk factors are more likely to get severe infections, which may require hospitalization. Risk factors include chronic conditions like asthma or heart disease, smoking, weakened immune system or being hospitalized. The pneumococcal vaccine can help protect you from getting the infection or fr