Pneumococcal Conjugate Vaccine and Otitis Media: Reality and Perspective

ABSTRACT & COMMENTARY

Synopsis: An efficacy study of the heptavalent pneumococcal conjugate vaccine showed a 57% reduction in cases of otitis media caused by vaccine serotypes, which resulted in a 6% overall decrease in the incidence of otitis media. The conjugate pneumococcal vaccine has a small additional benefit against otitis media, but the vaccine should not be promoted as a vaccine for otitis media.

Source: Eskola J, et al. Efficacy of a pneumococcal conjugate vaccine against otitis media. N Engl J Med. 2001;344:
403-409.

Eskola and colleagues conducting a prospective, randomized, double-blind, efficacy trial in Finland of the heptavalent pneumococcal conjugate vaccine, using hepatitis B vaccine as the control, found 2596 cases of otitis media (OM) among 1662 infants between 6.5-24 months of age. The efficacy of the vaccine was 6% (95% confidence interval, -4-16%) against acute OM from any cause, 34% (95% CI, 21-45%) against culture-confirmed pneumococcal OM, and 57% (95% CI, 44-67%) against pneumococcal OM caused by vaccine serotypes. The number of episodes attributed to serotypes that are cross-reactive with those in the vaccine was reduced by 51%, and the number of episodes caused by all other serotypes increased by 33%. Compared to the hepatitis B vaccine, the pneumococcal was more commonly associated with local reactions and with temperature > 39ºC.

Comment by Hal B. Jenson, MD, FAAP

The heptavalent pneumococcal vaccine (PCV7) was licensed by the FDA in February 2000 and is recommended for routine administration to all children at 2, 4, 6, and 12-15 months of age, and children 24-59 months of age at high risk of pneumococcal disease. The pneumococcal conjugate vaccine is recommended to prevent pneumococcal bacteremia, pneumonia, and meningitis.

Among children younger than 5 years of age, Streptococcus pneumoniae causes 17,000 cases of meningitis and 200 deaths annually in the United States. S pneumoniae is also the most common bacterial cause of OM, accounting for 28-55% of cases. The most common pneumococcal serotypes causing OM are 3, 6B, 9V, 14, 19F, and 23F; the vaccine serotypes are 4, 6B, 9V, 14, 18C, 19F, and 23F. The 7 million cases of acute OM each year in the United States account for 20 million office visits and 18% of ambulatory care visits among preschool children. Thus, even the modest 6% reduction in incidence of OM would theoretically prevent 1.2 million office visits annually. But it is important not to misrepresent the benefits of the vaccine as being a "vaccine for otitis media." This underemphasizes the greatest benefit of the vaccine in preventing invasive pneumococcal disease, and it overstates the modest 6% benefit on reducing the incidence of OM.

The 7 serotypes in the vaccine cause 80-90% of invasive pneumococcal disease. This study showed a 51% reduction in the number of episodes of OM caused by vaccine serotypes, with a relative increase of 33% in the number of episodes of pneumococcal OM caused by other serotypes. Whether the use of this heptavalent pneumococcal conjugate vaccine, or other conjugate vaccines currently in trials that contain up to 11 pneumococcal antigens, alters the epidemiology of the pneumococcal serotypes causing invasive disease or otitis media remains to be seen.