Prevnar is also approved to prevent ear infections caused by S. pneumoniae. However, the main reason to use Prevnar is to prevent IPD, as Prevnar is not very effective for preventing ear infections. There are many different causes of ear infections (including viruses or bacteria other than S. pneumoniae), and Prevnar's ability to protect against ear infections appears to be rather low.
How Does Prevnar Work?
Simply stated, the antigens in Prevnar "trick" the body into thinking it has been exposed to pneumococcal bacteria. The body produces antibodies that will help fight the bacteria if future exposure occurs.
A different pneumococcal vaccine (Pneumovax®) was available long before Prevnar and is used to prevent pneumococcal disease in adults and children over two years of age. However, the vaccine does not work well in infants and toddlers, since their immune systems are too immature to respond adequately to the vaccine.
Prevnar was developed specifically in a way to allow the young immune systems of infants and toddlers to respond to the vaccine. The bacterial antigens in Prevnar are bound or "conjugated" to a non-toxic diphtheria protein; this change produces a much better immune response in young children.
Prevnar Use in Older Children and Adults
Ideally, Prevnar will be given during infancy and toddlerhood, when the risk of IPD is quite high. However, the vaccine is approved for use in children up to nine years of age. For children over the age of two, your child's healthcare provider may decide to use Pneumovax instead, since Pneumovax prevents a wider range of S. Pneumoniae types, compared to Prevnar.