Saturday, June 11, 2011

Should I delay pneumococcal conjugate vaccine?

The pneumococcal conjugate vaccine is used in infants and young children to prevent infections by the bacteria Streptococcus pneumoniae. The vaccine contains inactivated or killed bacteria to stimulate the immune system against it. In 2000, the US Food and Drug Administration (FDA) licensed a 7-valent (protects against 7 serotypes of the bacteria) vaccine (PCV7), but this was replaced in 2010 with a 13-valent vaccine (PCV13), allowing greater protection. PCV13 is administered to children from 6 weeks up to 71 months according to the Centers for Disease Control (CDC). 

Traditionally, the pneumococcal conjugate vaccine was outlined for use by the National Institutes of Health (NIH) in children aged between 2 and 15 months, though the last booster could be up to 59 months. A different vaccine, pneumococcal polysaccharide vaccine (PPV23), is given to older children and adults because children under the age of 2 cannot mount the T cell response required. However, vaccination with PCV13 may be delayed for a number of different reasons.

Why vaccinate against pneumococcus?

In 2006, the World Health Organization (WHO) published a detailed review on pneumococcal infections and vaccination. According to the WHO review, 10 serotypes of pneumococcus are responsible for invasive pediatric infections, though 20 serotypes are responsible for infections in all age groups worldwide. Streptococcus pneumoniae usually colonizes the nasopharynx (the cavity behind the nose and above the throat). It typically does not cause infection or symptoms. However, when the bacteria spread to the ear or sinuses, or are aspirated into the lungs, it can cause an infection.

After the introduction of PCV7, the number of invasive infections decreased 80 percent, decreasing complications and death along with it. However, in 2006, the WHO pointed out that more than 1.5 million people, half of them under the age of 5 years, still die each year due to pneumococcal infection. Invasive S. pneumoniae causes pneumonia, meningitis, and blood infection, which are all serious diseases. Young age is a specific risk factor for pneumococcal infection, and one-quarter to one-half of pneumococcal meningitis survivors have long-term neurological disease. In addition, the antibiotics used to treat infection are becoming less and less useful due to bacterial resistance to treatment. Approximately 10 percent of infected children die according to the CDC.

Vaccination against the bacteria reduces the risk of invasive disease. It prevents pneumococcus-associated ear infections, pneumococcus-associated meningitis and long-term neurological damage and, most importantly, pneumococcus-related death. Young children are vaccinated because they are the population most at risk, though the elderly and HIV patients are also at-risk populations. The 2006 WHO review indicated that vaccinating children benefitted all age groups in the form of decreased disease.

Reasons for not vaccinating

Though most children can go into a pediatrician’s office or health department and get a vaccine without additional considerations, there are times when a vaccine should not be given. Pneumococcal conjugate vaccine may be delayed if the child has a current infection or illness more serious than a cold. Once they have recovered, they may be vaccinated. Some healthcare providers may choose to administer PCV13 separately from Hib vaccine due to potentially decreased efficacy, though the WHO does not find support for the practice.

Pneumococcal conjugate vaccine may be withheld (not given at all) when the child simply cannot tolerate it, such as in the case of a previous allergic reaction to any component of PCV7 or PCV13 or any vaccine containing diphtheria toxoid (DTaP). In addition, the WHO recommends that anyone who has already received PPV23 not receive PCV7 (and by equivalence PCV13).

Standard practice

Most children can and should be vaccinated with pneumococcal conjugate vaccine. Any exceptions can be discussed with your pediatrician.

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