Low rate of seroconversion after vaccination with a split virion, adjuvanted pandemic H1N1 influenza vaccine in HIV-1-infected patients

AIDS. 2010 Jun 1;24(9):F31-5. doi: 10.1097/QAD.0b013e3283398da1.


Objective: To determine rates of seroconversion after single vaccination with a novel split virion, inactivated, adjuvanted pandemic H1N1 influenza vaccine (A/California/7/2009) in HIV-1-infected patients (ClinicalTrials.gov Identifier: NCT01017172).

Design: Single center diagnostic study.

Setting: Institutional HIV outpatient department of an urban university clinic.

Participants: Adult HIV-1-infected individuals.

Intervention: Serum samples were taken before and 21 days after vaccination.

Main outcome measures: Antibody titers determined by hemagglutination inhibition assay. Seroconversion to vaccination was defined by either an antibody titer of 1: 10 or less before and of at least 1: 40 after or at least 1: 10 before and at least four-fold increase in antibody titer 21 days after single vaccination.

Results: One hundred and sixty patients (125 men/35 women) were analyzed. Before vaccination, 23 patients (14.4%) had a hemagglutination inhibition assay titer of at least 1: 40. A median of 22 +/- 3 days after vaccination, 110 (69%) patients seroconverted. Seroconverters were younger (45.1 +/- 10.0 vs. 48.8 +/- 11.3 years; P = 0.04), had a higher CD4 cell count (532 +/- 227 vs. 475 +/- 281 cells/microl; P = 0.03) and were more likely to have received a previous H5N1 vaccination in 2009 (25 vs. 8%; P = 0.02) when compared to nonresponders. No other significant differences were found comparing the two groups (prevaccination hemagglutination inhibition assay titer of > or =1: 40, AIDS, HAART, HIV RNA PCR <50 copies/ml or CD4 nadir, CD4 and CD8 percentage, sex, BMI, chronic hepatitis B or C).

Conclusion: Seroconversion after one dose of a split virion, inactivated, adjuvanted pandemic H1N1 influenza vaccine of HIV-infected patients was 69%. Studies to investigate whether a second dose of the vaccine will increase seroconversion rate are needed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Factors
  • Antibodies, Viral / blood*
  • CD4 Lymphocyte Count
  • Female
  • Germany / epidemiology
  • HIV-1*
  • Humans
  • Influenza A Virus, H1N1 Subtype / immunology*
  • Influenza Vaccines / administration & dosage
  • Influenza Vaccines / immunology*
  • Influenza, Human / epidemiology
  • Influenza, Human / prevention & control*
  • Male
  • Middle Aged
  • Virion / immunology*


  • Antibodies, Viral
  • Influenza Vaccines

Associated data

  • ClinicalTrials.gov/NCT01017172