Humoral immune response to two doses of pH1N1 vaccine.

Seroprotection- and seroconversion rates and geometric mean titers (GMT) to 2009 pandemic influenza A(H1N1) (pH1N1) virus for 57 HIV infected individuals and 44 healthy controls following vaccination with two doses of monovalent MF59-adjuvanted pandemic influenza vaccine (A/California/7/2009). Results are stratified by whether or not participants had been vaccinated with 2009–2010 seasonal trivalent inactivated influenza vaccine (TIV) before receiving the first pH1N1 vaccine.*For 51 HIV-infected participants who had already been vaccinated with 2009–2010 seasonal TIV at baseline (day 0), we also determined HI titers to 2009 pandemic influenza A(H1N1) virus in stored serum samples that had been collected before they received 2009–2010 seasonal TIV.#Baseline titers (day 0) were used as denominaters to determine seroconversion rates.