New PCV vaccine less effective when used in UK schedule

The new 13-valent pneumococcal vaccine (PCV) has recently been introduced in to the UK national immunisation schedule for children. This is a good thing because it increases the proportion of pneumococcal serotypes (or strains) being protected against from 75% to around 90%. However, there is a problem in the way the vaccine is used in the UK schedule: it is given as a 2-dose primary course. At 8 weeks it is given at the same time as the 5-in-1 vaccine, and at 12 weeks it is given with both the 5-in-1 and Men C vaccines. This strategy makes it significantly less effective than when given as a 3-dose infant schedule at 2,3 and 4 months. For example only 40% of infants are protected against one strain (6B) when vaccinated with the 2-dose UK schedule compared to nearly double the proportion of children (77%) who are protected against the same strain when vaccinated with the 3-dose schedule.
It seems that in our desire to minimise the number of injections we may be sacrificing vaccine effectiveness.

Added 14 June 2010