Pneumococcal pneumonia is the most serious and prevalent of the community-acquired respiratory tract infections. Although pneumococcal disease affects children and adults, the incidence of pneumococcal pneumonia increases in persons older than 40 years. Since 1974, penicillin-resistant pneumococci have emerged. The mortality rate from bacteremic pneumococcal infection exceeds 25% despite treatment with antibiotics.
The current unconjugated pneumococcal vaccine contains polysaccharide antigens from the 23 serotypes of Streptococcus pneumoniae most commonly found in bacteremic pneumococcal disease. The 23-valent pneumococcal polysaccharide vaccine (PPSV23) has been designed to induce a protective level of serum antibodies in immunocompetent adults and is highly effective in healthy young adults aged 19–64. Adults aged 65 years and older may receive the PPSV23 either alone or in combination with PCV13 (see discussion in the following paragraph), particularly if they are in a high-risk group (eg, a history of cardiac or respiratory disease, sickle cell disease, splenic dysfunction, renal and hepatic disease, or immunodeficiency). Those who receive pneumococcal vaccine before age 65 years should be revaccinated at age 65 if more than 5 years has passed since the initial vaccination. PPSV23 is not effective for children under the age of 2.
A pneumococcal conjugate vaccine (PCV) is recommended in the United States for all children younger than 5 years. In the United States, a 13-valent conjugate vaccine (PCV13) is typically used, while in Europe a 10-valent vaccine is more commonly used. PCV13 is administered in 4 intramuscular doses, given at 2, 4, 6, and 12–15 months of age. The vaccine provides coverage for approximately 80% of the invasive pneumococcal diseases in children in the United States. PCV is recommended for all infants and toddlers younger than 2 years, all children between 2 and 5 years of age who have chronic cardiopulmonary disorders or immune suppression, and some adults older than 65 years.
The duration of protection afforded by primary vaccination with pneumococcal vaccine seems to be 9 years or more.
A vaccine against Haemophilus influenzae type b (Hib) is recommended for all children before age 24 months. The vaccine has significantly reduced the number of infections caused by encapsulated Hib. In the past, meningitis comprised approximately 60% of Hib infections, amounting to about 10,000 cases each year in the United States. The type b capsule enhances the invasive potential of H influenzae; thus, the presence or absence of serum antibodies to these capsular antigens is a critical factor that determines an individual’s susceptibility to systemic Hib infection.
The vaccine significantly reduces the risk of contracting Hib-related epiglottitis, meningitis, and orbital cellulitis. The vaccine is available as a conjugated protein between the capsular polysaccharide PRP and other agents that increase the immunologic response (PRP-OMP and PRP-T). It is also available in combination with other vaccines, such as DTaP or meningococcus (Hib-MenCY), for increased patient convenience and adherence. The vaccine is administered in 3 or 4 doses, with the first dose given at age 2 months and the final dose after age 12 months. When the full series is given, the vaccine is more than 95% effective.
Excerpted from BCSC 2020-2021 series: Section 1 - Update on General Medicine. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.