MMWR. 2001;50:1140-1142
In September 2000, CDC published an interim vaccination schedule recommended by the Advisory Committee on Immunization Practices (ACIP) to be used during a pneumococcal conjugate vaccine shortage that was anticipated to be brief.1,2 Because the duration of the shortage has been longer and the severity has been greater than anticipated, ACIP has revised these recommendations to health-care providers who had been advised to conserve vaccine by decreasing the number of doses administered to healthy infants rather than to leave some infants unvaccinated. For infants who receive their first dose before age 6 months, vaccination with a maximum of 3 doses is recommended; the fourth dose should be deferred. All health-care providers should reduce the number of vaccine doses used and ordered, regardless of their current supply, so that vaccine is more widely available until supplies are adequate.
Because of greater-than-expected demand, vaccine has been back ordered for the public sector throughout most of 2001. In August, the situation worsened when facility and product testing-related limitations at the manufacturer's production sites halted distribution for several weeks. Under a full vaccination schedule, approximately 1.5 million doses are needed per month; the manufacturer estimates that 90% of the doses are used for the 4-dose infant vaccination series, and 10% are used for catch-up vaccination. During September, approximately 700,000 doses were distributed (47% of the 4-dose infant schedule), and in October, approximately 600,000 doses were distributed (40%). The manufacturer anticipates the distribution of approximately 1.2 million doses per month during November 2001-March 2002 (86%) and approximately 2.0 million doses per month during April 2002-mid-2002 (142%).
Until adequate supplies are available, ACIP recommends the following:
1. Vaccine should be administered to high-risk children aged <5 years as recommended by ACIP in October 2000,1 including children with sickle cell disease and other hemoglobinopathies; anatomic asplenia; chronic diseases (e.g., chronic cardiac and pulmonary disease, and diabetes); cerebrospinal fluid leak; human immunodeficiency virus infection and other immunocompromising conditions; immunosuppressive chemotherapy or long-term systemic cortico-steroid use, and children who have undergone solid organ transplantation.
2. Healthy infants and children aged <24 months should receive a decreased number of pneumococcal conjugate vaccine doses on the basis of the age at which vaccination is initiated and the estimated amount of vaccine available to the health-care provider's practice (Table 1). On the basis of birth, cohort size and recent experience with vaccine supply, if health-care providers estimate a shortfall of <25% of the 4-dose infant schedule, a moderate shortage schedule is recommended. If estimates suggest a greater shortfall, the severe shortage schedule is recommended. If shortages are estimated to be more severe (>50%), health-care providers should set infant vaccination priorities based on the assessment of risk, deferring infants at lowest risk. Demographic risk factors for invasive infections include being black or American Indian1; exposure risk factors include not breastfeeding and attendance at out-of-home child care.3
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TABLE 1. Updated recommendations for pneumococcal conjugate vaccine use among healthy children during moderate and severe shortages — Advisory Committee on Immunization Practices, 2001
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Limited data support a 2-dose schedule among infants; however, this regimen is preferable to vaccinating some children with 3 doses and not vaccinating others. Efficacy data from a randomized controlled trial prelicensure suggest that 1 or 2 doses of pneumococcal conjugate vaccine are protective during the 2-month interval before the next dose with a point estimate of 86% efficacy but a 95% confidence interval that includes zero.4 Immunogenicity data indicate increases in antibody titer following 2 doses for all vaccine serotypes except 6B.5 For all serotypes, 2 doses of conjugate vaccine probably increase antibody avidity and induce immunologic memory that is boosted by subsequent antigenic exposure. Acceptable 2-dose regimens include vaccination at ages 2 and 4 months, 2 and 6 months, or 4 and 6 months. The major advantage of regimens that begin at age 2 months is earlier provision of protection. Immunogenicity may be improved by increasing the interval between doses and vaccinating at ages 2 and 6 months or by vaccinating at ages 4 and 6 months. "Carrier priming" has been documented with the CRM197 Haemophilus influenzae type b conjugate vaccine,6 but the impact has not been evaluated for pneumococcal conjugate vaccine. Although immunogenicity would be greater if pneumococcal conjugate vaccination were deferred until after age 6 months (e.g., ages 7 and 9 months), this regimen would leave younger infants unprotected and would require additional vaccination visits.
3. Health-care providers should maintain a list of children for whom conjugate vaccine has been deferred so that it can be administered when the supply allows. The highest priority for vaccination among children who have been deferred is infants vaccinated with 2 doses. Infants who have received 3 doses and are eligible for a fourth dose would be a second priority group.
4. Pneumococcal polysaccharide vaccine is not licensed or recommended for children aged <2 years. Although a study indicated that administration of this vaccine at age 15-18 months may substantially boost antibody levels among children primed with 3 doses of conjugate vaccine (University of Chicago, unpublished data, 1995), this study did not use the licensed conjugate preparation. ACIP recommends additional study to evaluate the immune response to a polysaccharide vaccine booster dose among children aged 12-15 months.
Because data are limited on the long-term efficacy of a 3-dose or 2-dose vaccine regimen for young infants, health-care providers are encouraged to report invasive pneumococcal disease following pneumococcal conjugate vaccine to CDC through state health departments. If pneumococcal isolates are available from vaccinated children, CDC can perform serotyping to determine whether it is a type included in the vaccine. Additional information about this study is available at http://www.cdc.gov/nip/home-hcp.htm; other information is available at CDC's Respiratory Diseases Branch, telephone 404-639-2215; fax 404-639-3970.
