Evaluation of Seasonal Influenza Vaccine for 2010-2011 in Young Children

Overview

The seasonal influenza vaccination program for 2010-2011 will be the first to follow the H1N1 pandemic of 2009. Many children either had the H1N1 infection or the adjuvanted H1N1 vaccine. Both H1N1 infection and adjuvanted vaccine produced strong immune responses which could last for some time. The seasonal influenza vaccine for this fall will be a trivalent inactivated product (regular seasonal influenza vaccine)once again, without adjuvant. It will contain 3 strains of killed, split-apart viruses that might circulate this winter, including the H1N1 pandemic strain. It is theoretically possible that giving the H1N1-containing seasonal vaccine to people who still have some immunity to H1N1 virus could result in more frequent side-effects. However, there is no good evidence that pre-existing immunity to a strain in the vaccine does increase side-effects. In short, there could be nothing out of the ordinary this fall but it would be prudent to check this before public flu vaccination programs begin.

This study will assess the safety of seasonal influenza vaccination in children who received one or two doses of the adjuvanted H1N1 vaccine last year. It will also measure residual immunity to the H1N1 virus and immune responses to the seasonal vaccine. It will be carried out before the new vaccine is released for general use so that we have an accurate picture of vaccine safety and responses for other Canadians. A total of 200 children (50 at each site) 12-59 month olds, are being asked to participate in this study. A research nurse will conduct a telephone screening with potential participants to determine if they are eligible for the study. Volunteers must have had one or two doses of the adjuvanted H1N1 vaccine before January 31, 2010. To eligible participants do not need a previous years seasonal flu vaccine(TIV)however, this will be recorded. The study involves 1-2 vaccination visits 28 days apart. Those children who have not received a previous dose of TIV will receive a second dose at visit # 2. After each vaccination, there will be contacts 1 and 7 days later for a description of any symptoms experienced. A blood sample will be requested at at each study visit (2 or 3 visits depending on previous TIV history) to measure immune responses to the seasonal vaccine. The study will take 21-42 days to complete, depending upon whether or not the child received a previous dose of seasonal TIV vaccination. The 4 study sites are in Vancouver, Calgary, Montreal and Halifax. Each subject's parent will be asked to keep daily notes of any changes at the injection site (pain, redness, swelling) and any general symptoms (such as irritability, drowsiness, decreased appetite, sleep disturbance,sweating and shivering, including your axilla or rectal temperature, for 7 days after each vaccination. Major health changes will be assessed for 21 days post vaccination.