Pneumococcal vaccine failures. Two case reports and review.

In six patients (four described previously) who received the currently licensed pneumococcal vaccine (Pneumovax), severe pneumococcal disease developed from a type contained in the vaccine. All exhibited a poor or inconsistent antibody response to the vaccine. Immunosuppressive drugs and radiation used to treat existing disorders, predominantly Hodgkin's disease, appeared to be major factors responsible for the poor immune response. None were receiving antimicrobial prophylaxis at the time of the pneumococcal infection. We suggest that type-specific antibody at a level below 215 ng of antibody nitrogen per milliliter of serum may not be protective. More extensive vaccine trials in persons, particularly children, at high risk of severe pneumococcal disease are needed. The optimal time to immunize persons receiving radiation or immunosuppressive drugs remains to be established.