According to WHO pneumonia caused by streptococcus pneumoniae is the number one cause of vaccine preventable death below five years of age.So importance of pnemococcal vaccine is really great because of the resistance developed by the pathogen to most of the antimicrobial drugs.
According to PAHO,2 children die in every hour in pnemococcal pneumonia or pnemococcal disease in America below 5 years of age.
10 important things about pnemococcal vaccine
1) Two types of pnemococcal vaccines are available:
A) Pnemococcal polysaccharide vaccine (PPSV)
B) Pnemococcal conjugate vaccine( PCV)
Burden of pnemococcal disease
- 5 lakhs children below 5 years of age die annually in pnemococcal disease
- It is a leading cause of fatal bacterial pneumonia in developing countries.
- Most cases are seen below two years.
- Antimicrobial resistant serotypes have been evolving because of widespread use of antibiotics.
Pnemococcal polysaccharide vaccine
- This PPSV is an unconjugated 23 valent vaccine containing 25 microgram per dose of purified polysaccharide of the seotypes of pneumococcus–1,2,÷,4,5,6B,7F,8,9N,9V,10A,11A,12F,14,15B,17F,18C,19F,19A,20,22F,23F and 33F
- It is a T cell dependent vaccine.
- It covers almost 80 percent of serotypes involved for serious PD( pnemococcal disease)
- Dose is .5 ml Intramuscular or subcutaneous in the Detoid region.
- It is stored in 2-8 degrees centigrade .
But the data on the efficacy of PPV23 is little bit conflicting. It has not shown any efficacy against invasive disease or pneumonia in high risk population with underlying disease or highly immunosuppressive persons in both adults and children.
pnemococcal conjugate vaccine
In order to overcome the limitations of ppsv23,pnemococcal conjugate vaccine has been developed.
pcv13 contains polysaccharides of the capsules antigens of s.pneumoniae serotypes 1,5 7F 3,6A and 19A I’m ardition to the 7polysaccarides of the capsules antigen of 4,6B,9V 14,1Bc 19F and 23F present in the pcv-7.
a .5 ml of pcv 13 contains 2.2 microgram of polysaccharide form each of 12 serotypes .
It covers the three additional seotyprs besides PCV 7 ( 1,5 and 7F).It contains aluminium phosphate as an ajuvant.
WHO ctiteria for new PCV
WHO laid down following criteria to any new PCV has to fullfill the following 2 conditions:
- Immunoglobulin G of equal to or more than .35 microgram/ml
- The serotype specific IgG geometric concentration ratios.
Every year 12 th November is observed as world pneumonia day to make aware about the burden of PD and vaccination.