TABLE 1.
Characteristics of the groups of 3- to 5-year-old children whose stored sera were used in the study of anti-PRP antibody concentration and avidity
| Group | Yr of primary immunization | Yr of serum collection | No. of serum samples | Median age in yr (range) | PRP-T (Hib) vaccination modea | MenC vaccine in primary schedule |
|---|---|---|---|---|---|---|
| A | 1991 | 1994 | 87 | 3.6 (3.5-3.7) | Separate | No |
| B | 1995 to 1996 | 2000 | 79 | 4.5 (4.0-5.2) | NA | No |
| C | 1995 to 1996 | 2000 | 64 | 4.5 (4.1-4.9) | Reconstituted with DTwP | Mixed |
| D | 1997 to 1998 | 2002 | 72 | 4.0 (3.6-5.0) | Combination vaccine† | No |
| E | 1999 to 2000 | 2003 | 42 | 3.2 (3.0-3.4) | NA | Yes |
a
PRP-T (Hib) vaccination mode refers to whether the Hib vaccine was given at a separate site to other vaccines, reconstituted with DTwP vaccine prior to giving it at the same site, or in the form of a combination vaccine. NA, no confirmation available regarding the mode of administration of the PRP-T vaccine. †, two children given separate PRP-T vaccines and no confirmation of the mode of administration of the PRP-T vaccine for eight children.