The Seven-Valent Pneumococcal Conjugate Vaccine Reduces Tympanostomy Tube Placement in Children. Palmu AA, Verho J, Jokinen J, Karma P, and Kilpi TM. The Pediatric Infectious Disease Journal 2004;23(8):732-738.
Explanatory note: Streptococcus pneumoniae (“pneumococci”) are a group of more than 90 types (or serotypes) of bacteria that live in the noses and throats of people of all ages. Pneumococci can infect many different sites, some commonly—like the middle ear and the sinuses—and can also cause some less common but more serious infections, including infection of the lungs (pneumonia), central nervous system (meningitis), and blood stream (bacteremia).
A 7-valent pneumococcal conjugate vaccine (PCV-7), which contains the 7 most common pneumococcal serotypes causing invasive (serious) infections in children, was licensed in February 2000 in the United States for routine administration to children beginning at 2 months of age and in 2001 in the European Union. This vaccine has been shown to reduce the rates of invasive pneumococcal disease, lower the proportion of strains resistant to antimicrobial agents, and decrease the number of ear and sinus infections.
A number of bacteria, including pneumococci, cause recurrent attacks of ear infections—acute otitis media (AOM) or chronic otitis media with effusion (cOME)—in children. Some of these children require a surgical procedure called tympanostomy tube placement, by which a tube is placed in the infected ear drum to allow the middle ear to drain.
What was the impact of the 7-valent pneumococcal conjugate vaccine upon the subsequent tympanostomy tube placement among Finnish children who participated in a placebo controlled trial of the PCV-7 vaccine completed in 1999?
This study included children who had participated in the Finnish Otitis Media Vaccine Trial from 1995 to 1999. Those children had been vaccinated at 2, 4, 6 and 12 months of age with PCV-7 or hepatitis B vaccine (control group). After the study was completed all parents had been informed as to which vaccine their child had received during the study.
In spring 2001, researchers enrolled children—now 4-5 years of age—who had participated in the earlier trial and who were still living in the study area. If parents reported at the follow-up visit that their child had received a tympanostomy tube, the procedure was confirmed from their child’s medical records.
The researchers estimated vaccine efficacy by comparing all tympanostomy tube placement events between the group vaccinated with PCV-7 and the group vaccinated with the control hepatitis B vaccine.
Of the 1,490 eligible children, 756 agreed to participate. Of these, 403 had received PCV-7 vaccine and 353 had received the control vaccine. None of the children in either group had received any pneumococcal vaccine since completion of the original study. Additionally, no differences were noted between groups in other factors including gender, recent antibiotic usage, and day care outside of the home.
During the initial study period, children who had received the PCV-7 vaccine had a slightly lower rate of tympanostomy tube placement. However, in the period following the original study, children over 2 years of age had a more dramatic reduction in tympanostomy tube placements.
PCV-7 vaccine, when given at 2, 4, 6 and 12 months of age, had an efficacy against tympanostomy tube placement estimated to be 39% for children 2 to 4-5 years of age.
The PCV-7 vaccine, given in infancy, reduced the number of subsequent tympanostomy tube placements.
While it seems likely that PCV-7 vaccine given during infancy reduced the need for surgical tympanostomy tube placement, it is important to recognize there may have been selection bias among the children who participated in this study. The parents knew prior to deciding whether their child should participate in this study whether or not their child had received the PCV-7 vaccine. Further, many eligible children did not participate in the study, especially the control children. Indeed, the children who participated in this follow-up study had had more frequent bouts of ear infections during the original study period than did children who chose not to participate in the follow-up study. Despite the possible bias in patient selection this study adds to the growing body evidence that PCV-7 immunization is important for the prevention of ear infections and their complications.