The 2004 Recommended Childhood and Adolescent Immunization Schedule (see accompanying charts) is similar to the 2003 schedule. Three changes should be noted: (1) the dates of the schedule reflect the first one half of the year because of the anticipated addition of influenza vaccine for routine use in children six through 23 months of age for the fall of 2004; (2) the tetanus and diphtheria toxoids (Td) bar is broken into two segments: recommendation for Td at 11 to 12 years of age with catch-up from 13 to 18 years of age (compliance may be higher with Td given at 11 to 12 years of age, preventing a possible window of inadequate protection); and (3) to accommodate children who present for their six-month well-child visit slightly earlier than six months, the footnote wording of the minimum age for the third dose of hepatitis B vaccine now allows 24 weeks. The recommended age for the third dose of hepatitis B vaccine has not changed, remaining at six through 18 months of age. The minimal intervals of eight weeks between doses two and three and 16 weeks between doses one and three remain unchanged.

In children zero to two years of age, influenza-related hospitalization rates range from about 186 to 1,038 per 100,000 for healthy children to 800 to 1,900 per 100,000 for those with high-risk conditions, depending on exact age.^1–3 Izurieta, et al., found rates of 144 to 187 per 100,000 children zero to 23 months of age.^3,4 One study showed that healthy children six months to younger than three years of age had rates of influenza-associated hospitalization as high as or higher than rates in children three to 14 years of age with high-risk conditions.^1,2 In one study, influenza was second only to respiratory syncytial virus in causing hospitalizations in persons with chronic underlying illness.⁵ Neuzil, et al., found that for every 100 children, an annual average of six to 15 outpatient visits and three to nine courses of antibiotics are attributable to influenza.¹ The illness attack rate is highest in children and, in some studies, ranges from 14 to 40 percent yearly with attack rates sometimes higher than 30 percent in preschool-aged children.^6–8

Trivalent inactivated influenza vaccine (TIV) can cause local reactions such as soreness at the injection site. In young children not previously exposed to TIV, fever, malaise, and myalgia also can occur. At the October 2003 Advisory Committee on Immunization Practices (ACIP) meeting, a study was presented from the Vaccine Safety Datalink that found that no serious reactions were associated with influenza vaccination in 251,600 children younger than 18 years, including 8,446 children six to 23 months of age, who received more than 438,000 doses of TIV.

Based on the hospitalization rates in young children caused by influenza, the high annual illness attack rate, and the safety of vaccination, the ACIP encouraged, but did not formally recommend, routine TIV vaccination of healthy children six through 23 months of age beginning in the fall of 2002.³ The Centers for Disease Control and Prevention Vaccine Information Statement on Influenza has been updated to reflect this change (http://www.cdc.gov/nip/publications/VIS/default.htm). TIV is covered under the Vaccines for Children Program. Feasibility studies conducted by my team and others show that TIV can be added successfully to the routine childhood immunization schedule without delaying other childhood vaccinations. In October 2003, the ACIP voted to recommend routine annual vaccination of all children six to 23 months of age, effective in the fall of 2004. This gives manufacturers time to make enough vaccine and physicians time to order supplies. Because the 2004 schedule is harmonized between the ACIP, American Academy of Family Physicians (AAFP), and American Academy of Pediatrics, and because the other organizations have not yet voted on routine influenza vaccination in children six to 23 months of age, although all have encouraged it, the 2004 schedule covers only the first six months. Experts anticipate that a harmonized schedule for the last one half of 2004 will include routine influenza vaccination.

Live, attenuated influenza vaccine (LAIV) was licensed in 2003 for intranasal administration to healthy children and adults five to 49 years of age. In one sub-study, exacerbations of asthma were noted after LAIV in young children; thus, LAIV is not recommended for preschool-aged children until further safety data are available.

The shortage of pneumococcal conjugate vaccine (PCV) has resolved, and physicians are urged to recall children for whom a dose of PCV I was deferred because of the shortage. Data from the Active Bacterial Core surveillance system show PCV effectiveness at 94 percent. The incidence of invasive disease dropped dramatically in young children after PCV was introduced. Furthermore, among serotypes in PCV, herd immunity appears to be occurring with less disease in older age groups, including the elderly.

Useful Web sites for current information include http://www.immunizationed.org, a site developed by family physician educators that offers free Palm OS and Windows handheld applications of the childhood schedule, updates, and pictures of vaccine-preventable diseases. Other useful sites include http://www.immunize.org; https://www.aafp.org/about/policies/all/immunizations.html, which contains AAFP clinical policies on immunization; http://www.cdc.gov/nip; and http://www.immunizationinfo.org.