Disease & Vaccine Information

What is Pneumococcal?

Updated May 04, 2024

Image source: CDC PHIL

Pneumococcal disease is an infection caused by Streptococcus pneumoniae (S. pneumoniae) bacteria. S. pneumoniae bacteria are gram-positive, lancet shaped, facultative anaerobic bacteria and currently 100 known serotypes (strains) have been identified. Only a few of the strains cause the majority of pneumococcal infections but nearly all strains have the ability to cause serious disease. 

S. pneumoniae are frequently found in the respiratory tract and up to 90 percent of healthy people may have the bacteria present in the nasopharynx (upper area of the throat behind the nose). Between 20 and 60 percent of all school children may also carry the bacteria.  Colonization of S. pneumoniae in the nasopharynx tends to be the greatest at age three and declines thereafter. S. pneumoniae colonization in adults is generally acquired by exposure children, however the rates found in adults are lower than those seen in children. 

Most pneumococcal infections are mild; however, serious illness can occur.  S. pneumoniae can cause several types of infections, including pneumonia, ear infections, sinus infections, bloodstream infections (bacteremia) and meningitis.  Less commonly, S. pneumoniae can cause bacterial bone and joint infections,  pericarditis, endocarditis, and peritonitis. 

In adults, pneumococcal pneumonia is the most common form of pneumococcal disease. The incubation period of pneumococcal pneumonia is between one and three days and its initial symptoms of chills, rigors, and fever often occur abruptly. Other symptoms include a productive cough, rapid heart rate and breathing, shortness of breath, poor oxygenation, rust colored sputum, weakness, and malaise. Headache, vomiting, and nausea may occur as well, although less frequently. 

Pneumococcal bacteremia without pneumonia is another form of pneumococcal disease and symptoms include chills, fever, and a lower level of consciousness.  An estimated 4,000 cases of pneumococcal bacteremia occur yearly in the United States. 

Pneumococcal meningitis accounts for over 50 percent of all cases of bacterial meningitis in the United States. Symptoms of meningitis may include fever, stiff neck, irritability, vomiting, seizures, headache, light sensitivity, and coma. Approximately 2,000 cases of pneumococcal meningitis occur yearly in the United States and death occurs in approximately 22 percent of adults and 8 percent of children. 

In children, acute otitis media (middle ear infection) is the most common form of pneumococcal disease and S. pneumoniae can be found in up to 31 percent of ear aspirates. Before the age of one, over 60 percent of children will have at least one middle ear infection. Otitis media results in more medical office visits than any other childhood illness.  Symptoms of pneumococcal otitis media (middle ear infection) in children include fussiness, tugging at ears, sleeplessness, hearing difficulties, and balance issues.  In some children, ear infections can become chronic, resulting in recurrent antibiotic use or surgery to place tubes in the ears. 

Lab testing of blood or other body fluids such as cerebrospinal fluid, must be completed to confirm a diagnosis of S. pneumoniae. 

IMPORTANT NOTE: NVIC encourages you to become fully informed about Pneumococcal and the Pneumococcal vaccine by reading all sections in the Table of Contents , which contain many links and resources such as the manufacturer product information inserts, and to speak with one or more trusted health care professionals before making a vaccination decision for yourself or your child. This information is for educational purposes only and is not intended as medical advice.


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