ASPEN, COLO. — Two groups of immunocompromised children present special challenges in community-based practices, Elizabeth J. McFarland, M.D., said at a conference on pediatric infectious diseases, sponsored by Children's Hospital, Denver.
Weakened immune systems can make some vaccinations worrisome for youngsters taking high-dose steroids to control asthma and can make other vaccinations vital for children without a spleen, said Dr. McFarland, director of the hospital's immunodeficiency clinic.
Even more serious, she warned, is the risk of sepsis, with high mortality rates from postsplenectomy sepsis. Half of sepsis cases occur within 2 years of spleen removal, but 3% have been documented 20 years afterward (Br. J. Surg. 1991;78:1031–8).
Asthma and Steroid Issues
Dr. McFarland acknowledged that steroids are “important drugs” for controlling asthma.
The problem is that by interfering with cytokine production and lessening immune cell activity, steroids reduce the body's “ability to mount immune response or react to vaccine.”
According to Dr. McFarland, the American Academy of Pediatrics supports giving inactivated virus vaccines to children who are prescribed steroids, but she cautions that immunogenicity is uncertain. Live virus vaccines should be delayed until high-dose steroids are stopped.
If children take a high-dose steroid daily or on alternate days for more than 14 days, doctors should wait 1 month after stopping steroid use before giving vaccines, Dr. McFarland said. She also said that if the dosage period is less than 14 days, live virus vaccines can be given after stopping, but some experts recommend waiting 2 weeks.
The American Academy of Pediatrics recommends inactivated influenza vaccine for patients with asthma. Dr. McFarland said studies have shown similar antibody responses to the influenza vaccine in patients receiving inhaled steroids and short-course oral steroids, when compared with patients not receiving steroids at the time of immunization.
The live varicella zoster virus (VZV) vaccine is not recommended during high-dose steroid use, because vaccine safety is not established in this population. However, Dr. McFarland said a health maintenance organization study found that inhaled steroids given 3 months prior to VZV vaccination were not associated with increased risk of breakthrough disease (Pediatrics 2003;112:e98-e113), but the study did find increased breakthrough disease after VZV vaccination when oral steroids were given in the 3 months prior.
Postsplenectomy Issues
European studies have shown that about a quarter of physicians do not comply with guidelines for postsplenectomy care, Dr. McFarland said. She could not find any similar studies in the United States.
Although splenectomies in children may be necessary after trauma, she said the operation is being done less often owing to greater recognition of the spleen's importance to immune defense and to newer splenic salvage techniques. Dr. McFarland urged pneumococcal vaccination for postsplenectomy patients. About two-thirds of sepsis cases have been traced to Streptococcus pneumoniae in this population.
If the regular pneumococcal conjugate vaccine (PCV) series was not given before age 24 months, doctors should give two doses of PCV, she said. She recommended one dose of pneumococcal polysaccharide vaccine 6–8 weeks after PCV, and a second dose 3–5 years afterward.
Postsplenectomy children also should be vaccinated against meningococcus, according to Dr. McFarland. The new meningococcal conjugate vaccine (MCV4) is preferred for patients aged 11–55; only meningococcal polysaccharide vaccine (MPSV4) is approved for patients aged 2–11. Optimally, vaccinations for the encapsulated bacteria should be given prior to a planned splenectomy.
She suggested giving an extra dose of Haemophilus influenzae type b (Hib) vaccine prior to splenectomy, if possible.
Afterward, these children also should receive annual influenza shots, she said.
Daily antibiotic prophylaxis is recommended, especially in the first 2 years after splenectomy.
However, Dr. McFarland said the randomized studies supporting its use were performed in young sickle cell anemia patients with functional asplenia.
Determining when to discontinue daily prophylaxis is difficult, she said, as there are no direct data for children with splenectomies. Physicians should discuss the risks and benefits.
The recommended dosages are 125 mg of penicillin V twice daily in children under age 5 and 250 mg twice daily in children over age 5; some experts use amoxicillin (20 mg/kg daily).
Empiric therapy is another option, often used if daily prophylaxis is discontinued. At the first sign of a fever, the parents administer a dose of oral antibiotics and then bring in the child “pronto” for further evaluation.
Dr. McFarland recommended 50 mg/kg of amoxicillin/clavulanate potassium (Augmentin) divided into 2–3 dosages daily or an alternative, possibly a cephalosporin, if the child is allergic to penicillin.
Pneumococcal resistance to penicillin is a concern, she said, and she urged physicians to find out the rate in their community.