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More from InsideVaccines on Prevnar

Manufacturer’s Inserts and efficacy statements:

Efficacy against s. pneumoniae- 58.3- 98.9%
Efficacy against Otitis Medea (ear infection) regardless of serotype- 34%
Efficacy against all Otitis Medea regardless of etiology- 7%

More information on Prevnar and ear infections:

Efficacy of a Pneumococcal Conjugate Vaccine against Acute Otitis Media (Does Prevnar work in preventing ear infections?)

The vaccine reduced the number of episodes of acute otitis media from any cause by 6 percent (95 percent confidence interval, –4 to 16 percent [the negative number indicates a possible increase in the number of episodes]), culture-confirmed pneumococcal episodes by 34 percent (95 percent confidence interval, 21 to 45 percent), and the number of episodes due to the serotypes contained in the vaccine by 57 percent (95 percent confidence interval, 44 to 67 percent). The number of episodes attributed to serotypes that are cross-reactive with those in the vaccine was reduced by 51 percent, whereas the number of episodes due to all other serotypes increased by 33 percent.

So, Prevnar works for the groups of bacteria it was created to kill (up to 57%), but ear infections due to OTHER bacteria went up 33 percent.

Community-wide vaccination with the heptavalent pneumococcal conjugate significantly alters the microbiology of acute otitis media. (Demonstrating that the use of Prevnar changes the bacterial cause of ear infections).

RESULTS: Comparing each cohort (1992-1998 versus 2000-2003), the proportion of S. pneumoniae decreased from 48% to 31% (P = 0.009; relative risk, 0.754; 95% confidence interval, 0.628-0.906), and nontypable Haemophilus influenzae increased from 41% to 56%

The proportion of Gram-negative bacteria became 2-fold more frequent than S. pneumoniae in AOM in PCV7-vaccinated young children where PCV7 uptake was community-wide and supply was adequate.

These results show that while s.pneumoniae wasn’t causing ear infections as often, Gram-negative bacteria increased and filled in that “void” becoming twice as frequent (a specific type of Gram-negative coccobacillus (non-typable Haemophilus Influenzae)-increased as much as 15%).

Effect of pneumococcal conjugate vaccine on nasopharyngeal bacterial colonization during acute otitis media [Does Prevnar affect the amount of bacteria in your nasopharynx (where your ear canal, nose and throat all meet) during an ear infection?]

More recent studies have shown increases in the proportion of Haemophilus influenzae and Moraxella catarrhalis in the middle-ear fluid of PCV7-immunized children. There has been no report on the effect of PCV7 on all 3 bacterial pathogens combined, either in the middle-ear fluid or nasopharynx of individual children with AOM.

Although the nasopharyngeal colonization rate for S pneumoniae was not different between the 3 groups, a significantly higher proportion of PCV7-immunized children with AOM were colonized with M catarrhalis. Overall, the mean number of pathogenic bacteria types isolated from immunized children (1.7) was significantly higher than in controls (1.4). The increase in bacterial colonization of the nasopharynx during AOM could be associated with an increase in AOM pathogens and theoretically can predispose PCV7-immunized children with AOM to a higher rate of antibiotic treatment failure or recurrent AOM.

Essentially, researchers found that using Prevnar increased the overall number of pathogenic bacteria types from immunized children. Thus, possibly more ear infections that cannot be resolved with antibiotics.

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