Pneumococcal polysaccharide vaccine

Pneumococcal polysaccharide vaccine (PPSV)â€"the latest version is known as Pneumovax 23 (PPV-23)â€"is the first pneumococcal vaccine, the first vaccine derived from a capsular polysaccharide, and an important landmark in medical history. The polysaccharide antigens were used to induce type-specific antibodies that enhanced opsonization, phagocytosis, and killing of pneumococci by phagocytic cells. The pneumococcal polysaccharide vaccine is widely used in high-risk adults. As a result, there have been important reductions in the incidence, morbidity, and mortality from pneumococcal pneumoniae and invasive pneumococcal disease.

First used in 1945, the tetravalent vaccine was not widely distributed, since its deployment coincided with the discovery of penicillin. In the 1970s, Robert Austrian championed the manufacture and distribution of a 14-valent PPSV. This evolved in 1983 to a 23-valent formulation (PPSV23). A significant breakthrough impacting the burden of pneumococcal disease was the licensing of a protein conjugate heptavalent vaccine (PCV7) beginning in February 2000.

Indications

In the United States, PPSV is recommended for adults 65 years of age or older, adults with serious long-term health problems, smokers, children older than two years with serious long-term health problems, and even adults aged 55 years or younger, giving the protection of 5 years or more. The World Health Organization recommendations are similar. The WHO does not recommend use of PPV in routine childhood immunization programs. Pneumococcal vaccine is beneficial to control exacerbations of COPD and asthma.

In March 2011, The Joint Committee on Vaccination and Immunisation (JCVI) advised to stop using pneumococcal polysaccharide vaccine (PPV), for those aged 65 years and older. PPV should however still be offered to those in clinical risk groups.

PPSV is important for HIV patients. In Canadian HIV patients, the vaccine has been reported to decrease the incidence of invasive pneumococcal disease from 768/100,000 person-years to 244/100,000 patient-years. Current WHO guidelines recommend immunization with PPV-23 for HIV patients in clinical stage 1, while the CDC recommends immunization in those with a CD4 cell count greater than 200/μL.

Risks

Approximately half of people who receive PPSV experience pain and soreness at the vaccination site. Fewer than one percent develop a fever and/or muscle aches.

Vaccination schedule

Adults and children over two years of age

The 23-valent vaccine (e.g., Pneumovax 23) is effective against 23 different pneumococcal capsular types (serotypes 1, 2, 3, 4, 5, 6B, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15B, 17F, 18C, 19F, 19A, 20, 22F, 23F and 33F) and so covers 90 percent of the types found in pneumococcal bacteraemia.

Young children

Children under the age of two years fail to mount an adequate response to the 23-valent adult vaccine, and instead a 13-valent Pneumococcal Conjugated Vaccine (PCV) (e.g. Prevnar 13) must be used. Prevnar 13 is a new vaccine which has replaced Prevnar 7, adding six new serotypes to the vaccine. While this covers only thirteen strains out of more than ninety strains, these thirteen strains caused 80 percent to 90 percent of cases of severe pneumococcal disease in the US before introduction of the vaccine, and it is considered to be nearly 100 percent effective against these strains.

Special risk-group

Children at special risk (e.g. sickle cell disease and asplenia) require as full protection as can be achieved using the 13-valent congugated vaccine, with the then more extensive 23-valent vaccine given after the second year of life:

See also

• Streptococcus pneumoniae
• Pneumonia
• Conjugate vaccine

Notes and references

Further reading

• Moberley S, Holden J, Tatham DP, Andrews RM (2013). "Vaccines for preventing pneumococcal infection in adults". Cochrane Database Syst Rev 1: CD000422. doi:10.1002/14651858.CD000422.pub3. PMID 23440780. 

External links

• Pneumococcal Vaccines World Health Organization (WHO)
• Pneumovax 23 information Merck
• Pneumovax package insert Merck
• PATH's Vaccine Resource Library pneumococcus resources
• Centers for Disease Control and Prevention (2012). "Ch. 16: Pneumococcal Disease". In Atkinson W, Wolfe S, Hamborsky J. Epidemiology and Prevention of Vaccine-Preventable Diseases (12th ed.). Washington DC: Public Health Foundation. pp. 233â€"248. 

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