Pneumococcal Vaccine: Vaccinate! Revaccinate??

Community Acquired Pneumonia (CAP) causes about 500,000 hospitalizations in those older than 65 yearly in the US and is the 5th leading cause of death in people over 65.  Strep. Pneumo. is the most common cause of CAP.

The first vaccine in 1911 failed due to difficulties purifying and making the vaccine.  By 1940, 80 serotypes were identified and today, 90 serotypes are known.   The 23 serotypes chosen for the Pneumovax are the 23 that most commonly cause disease.  Pneumovax is made of purified pneumococcal capsular polysaccharide.  In 1977, 14 valent vaccine was developed and by 1983 this was modified to 23 valent vaccine.  It covers 88% of bacteremia producing strains.  Pneumovax should not be confused with PCV7, which is a conjugated vaccine used mostly in pediatrics.

CDC Indications
1) Age >65
2) Age >2 with: CHF, COPD, cirrhosis, DM.  Not for those with asthma without emphysema or steroid use.
3) High Risk Groups: Immunosupressed (HIV, heme malignancies, s/p transplant, nephrotic syndrome, on immunosuppressive drugs).

By CDC guidelines, once vaccinated, you will likely never need a revaccination.  However, this is a controversial area.

An initiative, Healthy People 2010 Initiative, has a goal of vaccinating 90% of those over age 65 with Pneumovax.  In 2002, 54% were vaccinated.  A single Pneumovax shot is likely to have 75% or more efficacy (serologically) in healthy adults > 65 years of age.

It should be noted that vaccination does NOT reduce pneumonia.  A meta-analyses shows no decrease in pneumonia incidence as a result of vaccination, however it has been shown to be about 60-70% effective in preventing invasive disease (meningitis, bacteremia).  Only one study by Riley et al (Lancet. 1977 Jun 25;1(8026):1338-41) has demonstrated decreased mortality (by 44%).  Other studies to date have not been powered to do so or have not shown a statistically significant difference.  There are 40-50,000 cases of bacteremia plus 3-6,000 cases of meningitis.  Maybe half of these would be vaccine preventable.

In a retrospective study by Jackson et al (NEJM 2003 348;18:1747-1755) 47,365 adults >65 over 3 years were reviewed.  1428 hospitalizations and 3061 outpatient visits were due to Community Acquired Pneumonia.  From these data the following relative risks were found:

  • Pneumococcal Bacteremia: 0.56 (0.33-0.93)
  • Hospitalization: 1.14 (1.02-1.28)
  • Outpatient Pneumonia: 1.04 (0.96-1.13)
  • Any CAP: 1.07 (0.99-1.14)

5 Meta-analyses agree with the above findings.

Case 1
A 66 year old man presents with mild intermittent asthma (on albuterol) and hypertension.  He is very healthy.   He is a fisherman and spends a lot of time on his boat.  The patient agrees to Tetanus immunization but unsure about receiving the Pneumovax immunization.

In this case, due to his age (over 65), pneumococcal vaccination is indicated.  If this patient had been 63, Pneumovax would not be indicated in spite of his asthma.  Asthma is not a CDC recommended reason for immunization.

Case 2
An 86 year old man presents with history of diabetes, hypertension, hypothyroidism, early dementia.  He has had 2 previous hospitalizations for pneumonia in the late 1980’s.  No ICU stays.  He got the “pneumonia vaccine” but “it’s been many years” (early-mid 1990’s).

The question now is one of revaccination.  This is a controversial area.  By CDC guidelines, revaccination is not indicated as the patient was vaccinated after age 65.  However, many physicians would state revaccination is indicated due to the number of years that have passed.  Revaccination is NOT an effective way to boost the immune response and decrease the risk for pneumococcal disease.

Current CDC guidelines about revaccination for those over the age of 65 can be summarized by the following questions:

1) Has the person been vaccinated previously?
No or unsure –> give the vaccine
If yes –>  then answer next question

2) Was the person older than 65 at the time of last vaccination?
Yes  –> No vaccine
No  –> Give vaccine if more than 5 years since last vaccine, otherwise wait until 5 years have passed.

Following vaccination with PPV23, antibody levels decline after 5–10 years and decrease more rapidly in some groups than others.  However, the relationship between antibody titer and protection from invasive disease is not certain (i.e., higher antibody level does not necessarily mean better protection), so the ability to define the need for revaccination based only on serology is limited.  In addition, currently available pneumococcal polysaccharide vaccines elicit a T-independent response, and do not produce a sustained increase (“boost”) in antibody titers.  Available data do not indicate a substantial increase in protection in the majority of revaccinated persons.

Routine revaccination not indicated with the exception of only high-risk groups. This does not include DM and asthma not on steroids.  COPD and smokers will be added with the next set of CDC guidelines.  Generally, wait 5 years if you’re going to revaccinate.  If the patient was vaccinated before age 65, give again after 65 if 5 years have passed. Why 5 years?  If revaccination occurs in <5 years, side effects are increased over first-time takers and severe localized (arthrus-type) reactions are more frequent.

High risk groups per the CDC are:  functional or anatomic asplenia (e.g., sickle cell disease or splenectomy), HIV infection, leukemia, lymphoma, Hodgkins disease, multiple myeloma, generalized malignancy, chronic renal failure, nephrotic syndrome, or other conditions associated with immunosuppression (e.g., organ or bone marrow transplantation) and those receiving immunosuppressive chemotherapy, including long-term corticosteroids.

This said, a paradox exits.  Older and ill patient are those that revaccination is recommended, yet they respond least well to the vaccine (serologically).  Age 65 is arbitrary.  There are worse responses and a shorter length of efficacy with increasing age.  We say to revaccinate high risk patients, however, high risk people respond least well to the vaccine and for the shortest period of time.