Discordant immunization schedules can complicate vaccine evaluation for Europe

Abstract

Background: Most of the world’s vaccines are produced in Europe. Although vaccine licensure can be
centralized through the EMEA, immunization recommendations are established at the national levels,
reimbursement policies vary widely (ranging from regional to national, from private to public) and the lag time
can be long between licensure and eventual introduction into a national immunization program.
Methods: An example of this discordance is the paediatric combination vaccines. Young infants in some EU
countries receive a whole-cell pertussis vaccine, in a three- to five-vaccine combination (“DTPw | IPV | Hib”).
Acellular pertussis vaccines have been introduced over the last decade in many other EU countries, with four-
to six-vaccine combinations (“DTPa | IPV | HBV | Hib”). Either of these combinations may be administered with
a “3 + 1” schedule, with the first dose given between the age of 2 to 3 months, a spacing of 1 to 2 months
between doses, and the final (booster) dose usually given at anywhere between 12 and 24 months of age, but
in a handful of countries as late as the age of 3 to 5 years. By contrast, a “2 + 1” schedule is applied in some
countries for the “DTPa | IPV | Hib” or “DTPa | IPV | HBV | Hib” vaccines: first dose, 3 months old; spacing, 2
months between doses; final (booster) dose, 11 to 14 months of age.
Results: Differing national policies in the EU may have led to delays in the introduction of the newest vaccines
(e.g., pneumococcal conjugate, meningococcal conjugate, rotavirus, influenza, varicella-zoster, etc.) that
must be shown to be compatible with the various infant immunization programs across Europe. This could
delay the likelihood, in some EU countries, of the public health advancements that these new vaccines can
provide.
Conclusions: Sharing of best practices from vaccination schedules might rationalize vaccine development,
streamline the introduction of novel vaccines into the national immunization programs, and facilitate the
evaluation of the impact of new vaccines in Europe.