Pneumococcal disease is any infection caused by the bacterium Streptococcus pneumoniae, ranging from common ear infections to life-threatening conditions like meningitis and bloodstream infections. More than 100 different strains of this bacterium exist, though only a fraction cause most infections. The disease spreads through respiratory droplets and can escalate quickly, with an incubation period as short as one to three days for pneumonia.
How Pneumococcal Disease Spreads
The bacterium lives in the nose and throat and spreads when an infected person coughs, sneezes, or talks. Many people carry it without ever getting sick. Problems start when the bacteria move beyond the nose and throat into the lungs, bloodstream, or the protective lining around the brain and spinal cord. Young children are especially efficient carriers, often spreading the bacterium to family members and other close contacts.
Invasive vs. Non-Invasive Forms
Doctors divide pneumococcal disease into two broad categories based on where the bacteria end up in the body.
Non-invasive disease stays in the upper respiratory tract. This includes ear infections and sinus infections. These are far more common and generally less dangerous, though ear infections are a leading reason for pediatric doctor visits and antibiotic prescriptions.
Invasive disease occurs when the bacteria enter parts of the body that are normally sterile, like the blood, spinal fluid, or lungs. The three major invasive forms are pneumonia (lung infection), bacteremia (bloodstream infection), and meningitis (infection of the lining around the brain and spinal cord). These are medical emergencies.
Symptoms by Type of Infection
Symptoms depend on which part of the body is infected, and they can look quite different from one form to another.
Pneumonia causes chest pain, cough, fever with chills, and rapid or difficult breathing. In older adults, the classic signs may not appear at all. Instead, confusion or unusual drowsiness may be the only clue.
Meningitis produces a high fever, severe headache, stiff neck, confusion, and sensitivity to light. Babies with meningitis often show different signs: poor feeding, low alertness, and vomiting.
Bacteremia tends to present with fever, chills, and low alertness. Because the infection is in the bloodstream, it can seed bacteria to other organs and progress to sepsis rapidly.
Ear infections cause ear pain, fever, sleepiness, and a red, swollen eardrum. Sinus infections bring facial pain or pressure, headache, runny or stuffy nose, post-nasal drip, and sometimes a sore throat or bad breath.
Potential Complications
The invasive forms of pneumococcal disease carry significant fatality rates. Pneumococcal pneumonia kills about 1 in 20 people who develop it. It can also lead to collapsed lungs, lung abscesses, fluid buildup around the lungs, and inflammation of the outer lining of the heart.
Meningitis is particularly devastating. About 1 in 12 children and 1 in 6 older adults with pneumococcal meningitis die from the infection. Survivors may face lasting problems, including hearing loss and developmental delays in children.
Bacteremia kills roughly 1 in 30 children and 1 in 8 adults who get it. In some cases, it can lead to limb loss. Any of the serious invasive infections can progress to sepsis, a body-wide inflammatory response that can cause organ failure.
Who Is Most at Risk
Age is the single biggest risk factor. Children younger than 2 have immature immune systems that struggle to fight off the bacterium’s protective outer capsule. Adults 65 and older face elevated risk because immune function naturally declines with age.
Between those age extremes, certain conditions raise vulnerability substantially. These include a weakened immune system (from HIV, cancer treatment, or organ transplant medications), a missing or non-functioning spleen, chronic heart or lung disease, diabetes, alcoholism, and cochlear implants or cerebrospinal fluid leaks, which create physical pathways for bacteria to reach the brain.
How It Is Diagnosed
If your doctor suspects pneumococcal disease, the testing approach depends on the suspected infection. For pneumonia, a urine sample is often collected for a pneumococcal antigen test, which detects bacterial proteins quickly. For suspected meningitis or a bloodstream infection, a sample of cerebrospinal fluid or blood is taken.
Lab technicians may run a bacterial culture, growing the organism from your sample to confirm the diagnosis and identify the specific strain. A PCR test, which detects the bacterium’s genetic material, can also be used and often returns results faster than a culture. These tests help determine not just whether the bacterium is present but also which antibiotics will work against it.
Antibiotic Resistance
Treatment typically involves antibiotics, but resistance has become a real concern. Today, about 2 in 5 pneumococcal infections involve bacteria that are resistant to at least one antibiotic. This means the first antibiotic prescribed may not work, potentially delaying effective treatment. Resistance to penicillin-class drugs and a common group of antibiotics used for respiratory infections has been rising for years, which makes accurate lab testing before or during treatment especially important.
Vaccination for Children
Vaccination is the most effective way to prevent pneumococcal disease. The CDC recommends all children under 5 receive a four-dose series of pneumococcal conjugate vaccine at 2 months, 4 months, 6 months, and between 12 and 15 months of age. Two vaccine options, PCV15 and PCV20, are available. These vaccines have dramatically reduced invasive pneumococcal disease in children since their introduction.
Vaccination for Adults
Adults 50 and older who have never received a pneumococcal conjugate vaccine (or whose vaccination history is unknown) are recommended to get one. Three options are currently available: PCV15, PCV20, and PCV21.
If you receive PCV20 or PCV21, your pneumococcal vaccination is complete with that single visit. If you receive PCV15, you will need a follow-up dose of a different pneumococcal vaccine (PPSV23) about a year later. For people with weakened immune systems, cochlear implants, or cerebrospinal fluid leaks, the gap between those two doses can be shortened to as little as eight weeks.
Adults 65 and older who previously received an older vaccine (PCV13) along with PPSV23 after turning 65 can discuss with their doctor whether getting PCV20 or PCV21 would provide additional benefit. This is considered a shared decision rather than a blanket recommendation.
Global Impact
Pneumococcal disease remains a leading killer of young children worldwide. Children under 5 bear the highest mortality rates of any age group, with peak death rates reaching roughly 23.5 per 100,000 children globally. In the United States, pneumonia (from all causes, not just pneumococcal bacteria) contributed to over 41,000 deaths in 2024. Access to conjugate vaccines has reduced the burden significantly in high-income countries, but in regions with lower vaccination coverage, pneumococcal disease continues to cause substantial childhood mortality.