Antibody responses to natural influenza A/H1N1/09 disease or following immunization with adjuvanted vaccines, in immunocompetent and immunocompromised children

Vaccine. 2011 Apr 27;29(19):3548-57. doi: 10.1016/j.vaccine.2011.02.094. Epub 2011 Mar 17.


Objectives: To compare antibody responses elicited by influenza A/H1N1/09 disease and immunization with adjuvanted vaccines, in immunocompetent or immunocompromised children.

Study design: Prospective parallel cohort field study enrolling children with confirmed influenza A/H1N1/09 disease or immunized with 1 (immunocompetent) or 2 (immunocompromised) doses of influenza A/H1N1/09 squalene-based AS03- or MF59-adjuvanted vaccines. Antibody geometric mean titers (GMT) were measured by hemagglutination inhibition (HAI) and microneutralization (MN) assays 4-6 weeks after vaccination/disease. Vaccine adverse events were self-recorded in a 7-day diary.

Results: Antibody titers were as high in 48 immunocompetent children after a single immunization (HAI and MN seroprotection rates: 98%; HAI-GMT: 395, MN-GMT: 370) as in 51 convalescent children (seroprotection rates: 98% (HAI) and 92% (MN); GMT: 350 (HAI) and 212 (MN). Twenty-seven immunocompromised children reached slightly lower seroprotection rates (HAI: 89%, MN: 85%) but similar antibody titers (HAI-GMT: 306, MN-GMT: 225) after 2 immunizations. Adverse events increased with age (P=0.01) and were more frequent with Pandemrix® than Focetria® (P=0.03).

Conclusions: Similarly high seroresponses may be expected in immunocompetent children after a single dose of adjuvanted vaccines as responses of convalescent children. Two vaccine doses were sufficient for most immunocompromised children.

Trial registration: NCT0102293 and NCT01022905.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adjuvants, Immunologic / administration & dosage
  • Adjuvants, Immunologic / adverse effects
  • Adolescent
  • Antibodies, Viral / blood
  • Antibody Formation*
  • Child
  • Child, Preschool
  • Female
  • Hemagglutination Inhibition Tests
  • Humans
  • Immunization
  • Immunocompromised Host*
  • Influenza A Virus, H1N1 Subtype / immunology*
  • Influenza Vaccines / immunology*
  • Influenza, Human / immunology*
  • Influenza, Human / prevention & control
  • Male
  • Neutralization Tests
  • Prospective Studies
  • Squalene / administration & dosage


  • Adjuvants, Immunologic
  • Antibodies, Viral
  • Influenza Vaccines
  • focetria
  • pandemrix
  • Squalene

Associated data