A new, 13-valent pneumococcal conjugate vaccine (PCV13, Prevnar 13), from Wyeth Pharmaceuticals was licensed by the US Food and Drug Administration (FDA) in February for use in all children ages 6 weeks to 59 months. The new vaccine was licensed for the prevention of invasive pneumococcal disease (pneumonia, meningitis, and bacteremia) and otitis media.1 PCV13 is meant to replace the 7-valent PCV7 (Prevnar), and will offer protection against a wider array of pneumococcal serotypes.1
Invasive pneumococcal disease in kids has diminished substantially
Soon after PCV7 was included in the routine child immunization schedule, the incidence of invasive pneumococcal disease (IPD) began to decline.2-5 In 1 study, the annual rate of IPD among children younger than 5 years of age decreased from 98.7 cases/100,000 in 1998–1999 to 22.6 cases/100,000 in 2006-2007.3 This decline was due to a decrease in the rate of disease caused by the 7 vaccine serotypes, from 81.9 cases/100,000 to 0.4 cases/100,000.
However, during that same time period, the rate of IPD caused by nonvaccine serotypes increased from 16.8 cases/100,000 population to 22.1 cases/100,000.3 The percentage of IPD caused by nonvaccine serotypes rose from 20% to 90% among children younger than 5 years of age during that time period.3
Fewer cases in adults, as well
In addition to the decline of IPD in children, there has also been a decline in adults. In those older than age 65, the rate of IPD decreased from 60.1/100,000 to 38.2/100,000 between 1998 and 2007—most likely because routine use of the PCV7 vaccine in children has resulted in decreased carriage and transmission of infection from children to adults.3 As in children, the decline was due to a decreasing incidence of infection from PCV7 vaccine serotypes, from 33.7 cases/100,000 to 3.3 cases/100,000. At the same time, the rate of disease caused by nonvaccine serotypes increased from 26.4 cases/100,000 to 34.9 cases/100,000.3
Nonvaccine serotypes still cause concern
While the overall decline in IPD has been a public health success, the increase in incidence of disease caused by nonvaccine serotypes has been cause for concern. According to an analysis of 2007 data from the Centers for Disease Control and Prevention (CDC)’s Active Bacterial Core surveillance, 64% of IPD cases in children younger than 5 years of age in 2006-2007 were caused by serotypes 1, 3, 5, 6A, 7F, and 19A.6 Several of these replacement serotypes have high levels of resistance to penicillin and erythromycin. This trend is what led to the development of the PCV13, which adds these 6 to the 7 serotypes covered by Prevnar.
The dosing schedule is complicated
The recommended schedule for the older PCV7 vaccine has always been a challenge, because the number of doses depends on the age of the child when first vaccinated.7,8 The introduction of PCV13 adds to the complexity, because many children will be in the midst of a PCV7 series when they make the transition to PCV13.
The Advisory Committee on Immunization Practices (ACIP) recommendations on how many doses of PCV13 a child should receive depend now on the age at which the first PCV vaccine was received (either PCV7 or PCV13), the number of doses of each received, and the presence or absence of high-risk medical conditions. These recommendations are summarized below and illustrated in TABLE 1 and TABLE 2.
TABLE 1
PCV13: Routine vaccination schedule
| Age at first dose | Primary series* | Booster dose† |
|---|---|---|
| 2-6 months | 3 doses | 1 dose, 12-15 months |
| 7-11 months | 2 doses | 1 dose, 12-15 months |
| 12-23 months | 2 doses | None |
| 24-59 months, healthy children | 1 dose | None |
| 24-71 months for children with certain chronic diseases or immunocompromising conditions (see TABLE 3) | 2 doses | None |
| *Minimum interval between doses is 8 weeks, except for children vaccinated at <12 months for whom the minimum interval is 4 weeks. Minimum age for first dose is 6 weeks. | ||
| †Given at least 8 weeks after previous dose. | ||
| Source: CDC. MMWR Morb Mortal Wkly Rep. 2010.1 | ||
TABLE 2
In transition: From PCV7 to PCV13
| Infant series | Booster dose | Supplemental PCV13 dose | ||
|---|---|---|---|---|
| 2 months | 4 months | 6 months | ≥12 months* | 14-59 months† |
| PCV7 | PCV13 | PCV13 | PCV13 | None |
| PCV7 | PCV7 | PCV13 | PCV13 | None |
| PCV7 | PCV7 | PCV7 | PCV13 | None |
| PCV7 | PCV7 | PCV7 | PCV7 | PCV13 |
| *No additional PCV13 doses are indicated for children ages 12-23 months who have received 2 or 3 doses of PCV before age 12 months and at least 1 dose of PCV13 at ≥12 months. | ||||
| †For children with underlying medical conditions (see TABLE 3), a single supplemental PCV13 dose is recommended through age 71 months. | ||||
| Source: CDC. MMWR Morb Mortal Wkly Rep. 2010.1 | ||||
For a child who started PCV7 on time and is in mid series, the recommendation is to simply finish the series with PCV13.
If a child has completed a series of PCV7, the recommendation is to give him or her 1 dose of PCV13 up to age 59 months. (If the child has a chronic underlying medical condition, this age is extended to 71 months.1)