Background: The 7-valent CRM197 pneumococcal conjugated vaccine (PCV7) was originally licensed using 3 primary doses during infancy and a booster in the second year of life. We compared the originally licensed regimen to 2 widely used alternative regimens.
Methods: Five hundred forty-three infants were randomized to receive PCV7 at 2, 4, 6, and 12 months (3 + 1), at 4, 6, and 12 months (2 + 1), or at 2, 4, and 6 months (3 + 0). Blood was drawn at 2, 7, 13, and 19 months. Serotype-specific IgG concentrations were determined by ELISA.
Results: In the 2 + 1 group, postprimary IgG concentrations against serotypes 6B, 14, 18C, and 23F were reduced compared with the 3 + 1 or 3 + 0 groups. Both 3 + 1 and 2 + 1 groups showed marked booster response, but the 2 + 1 group had reduced concentrations against serotypes 6B, 18C, 23F. At 19 months, IgG antibodies decreased in both 3 + 1 and 2 + 1 groups but the 2 + 1 group had significantly lower concentrations against serotypes 6B, 18C, and 23F. IgG concentrations decreased in the 3 + 0 group during the second year and were significantly lower than those of 3 + 1 and 2 + 1 for all serotypes at 13 and 19 months.
Conclusions: Significant differences in immunogenicity were documented between the reduced and the licensed regimens. The clinical implications of these differences require further studies.
From the Pediatric Infectious Disease Unit, Faculty of Health Sciences, Ben-Gurion University of the Negev and Soroka University Medical Center, Beer-Sheva, Israel.
Accepted for publication February 17, 2010.
Supported in part by Wyeth Grant No. 0887X-101801, and Berna/Crucell, Wyeth, and MSD (to R.D.)
Conflicts of interest: Ron Dagan is a scientific consultant with Berna/Crucell, GlaxoSmithKline, Novartis, Wyeth, Protea, and MSD, and speaker at Berna/Crucell, GlaxoSmithKline, and Wyeth, and holds shares of Protea. David Greenberg is a speaker at Wyeth and GlaxoSmithKline.
Address for Correspondence: Ron Dagan, The Pediatric Infectious Disease Unit, Soroka University Medical Center, Beer-Sheva, Israel. E-mail: firstname.lastname@example.org.