Sometimes, it’s important to remember that there are solid answers to the question “why do we vaccinate our children?” Frequently, we focus on what vaccines don’t do, like they don’t cause autism, and forget to forcefully remind the public of the benefits of vaccines – preventing diseases. Recent research, published in Pediatrics, provides valuable evidence that bacteremia risk drops significantly after receiving the 7-valent (this vaccine contains 7 different pneumococcal antigens) and 13-valent pneumococcal conjugate vaccines. (See Note 1)
Bacteremia, the presence of bacteria in what should be sterile blood, is a common complication of pneumococcal pneumonia. And about 1 out of 100 children die from it, so it is considered a very dangerous condition for children (and older adults). Preventing pneumonia, along with the subsequent bacteremia, with the pneumococcal conjugate vaccine is one of the best reasons to vaccinate your children.
Bacteremia frequently evokes an immune system response called sepsis, which consists of serious symptoms such as fever, chills, and low blood pressure. Bacteremia may induce severe immune responses which can lead to potentially fatal conditions such as septic shock and multiple organ dysfunction syndrome. In the most severe cases, the bacteremia infection can travel through the blood stream and cause infections in distant locations, such as endocarditis (infections of the heart), meningitis (infections of structures around the brain), and osteomyelitis (bone infections).
Greenhow et al., from Kaiser Permanente Northern California, a vertically integrated health management system, examined the incidence of bacteremia in children 3-36 months old. They looked at the data in three time periods between 1 September 1998 through 31 August 2014. The first period, pre-PCV7 (7-valent pneumococcal conjugate vaccine) , was before the pneumococcal conjugate vaccine was available. The second period, post-PCV7/pre-PCV13 (13-valent pneumococcal conjugate vaccine), was after PCV7 was introduced but before PCV13. And finally, the third period, post-PCV13, included the period when Kaiser switched all of its pneumococcal vaccines to the PCV13 version.
The researchers designed a retrospective case control study which reviewed the blood culture results collected from children 3 to 36 months old, between 1 September 1998 through 31 August 2014, who were seen in Kaiser Northern California outpatient clinics, emergency departments, and within the first 24 hours of hospitalization. The researchers collected results from 57,733 blood cultures during that period to see what changes in bacteremia were observed after implementation of the vaccine.
The researchers found that the incidence of Streptococcus pneumoniae bacteremia dropped from 74.5 per 100,000 children in the pre-PCV7 period, to 10 in the post-PCV7/pre-PCV13 period, all the way to 3.5 by the post-PCV13 period. That represents a 95.3% reduction in Streptococcus pneumoniae bacteremia after introduction of the pneumococcus vaccine, an impressive number that directly reduces serious complications for children.
Interestingly, the researchers also found that Streptococcus pneumoniae makes up a smaller percentage of bacteremia cases. After introduction of the vaccine, which caused the precipitous drop in Streptococcus pneumoniae bacteremia incidence, other bacteria, especially Escherichia coli, Salmonella, and Staphylococcus aureus, are now responsible for 77% of bacteremia cases. New vaccines may become available in the future to prevent
What can we conclude from this study? Routine immunizations against pneumococcal bacteria have made bacteremia in healthy toddlers an extremely rare event. And given that bacteremia can have very dangerous complication for children, this is an important reason why we vaccinate.
- There is a 23-valent pneumococcal polysaccharide vaccine, called Pneumovax 23 (PPV-23), which is not in the vaccine schedule for children. It is mostly given to older adults, although children who are at risk to pneumococcus because of a pre-existing condition can be safely given PPV-23 if necessary.
- Greenhow TL, Hung YY, Herz A. Bacteremia in Children 3 to 36 Months Old After Introduction of Conjugated Pneumococcal Vaccines. Pediatrics. 2017 Mar 10. pii: e20162098. doi: 10.1542/peds.2016-2098. [Epub ahead of print] PubMed PMID: 28283611.