The patients of pediatric haemato-oncology have a higher risk for novel H1N1 influenza infection than general population, and they are strongly recommended to receive novel H1N1 vaccination. However, there is no previous data to answer how the efficacy and effectiveness of novel H1N1 vaccination is in patients of pediatric haemato-oncology. This study is designed to investigate the antibodies titers before and after the novel H1N1 influenza vaccination in these patients. Titer of H1N1 influenza virus antibodies will be determined by hemagglutinin inhibition assay (HAI). A HAI titer with a 4-fold rise or greater is defined as seroconversion. Study subjects with seroconversion are regarded as responsiveness to the vaccination. Meanwhile, if the patient presents influenza-like symptoms, we will perform throat swab or nasal swab for influenza rapid test, viral isolation, and novel H1N1 influenza PCR to confirm the diagnosis. After the study, we will be able to know whether or not current novel H1N1 influenza vaccination schedule is adequate and efficient for pediatric haemato-oncology patients.

The emergence of novel H1N1 influenza in 2009 has a great impact to the societies in Taiwan and worldwide. The patients of pediatric haemato-oncology have a higher risk for novel H1N1 influenza infection than general population, and they are strongly recommended to receive novel H1N1 vaccination. However, there is no previous data to answer how the efficacy and effectiveness of novel H1N1 vaccination is in patients of pediatric haemato-oncology. This study is designed to investigate the antibodies titers before and after the novel H1N1 influenza vaccination in these patients. Thus two blood samples will be drawn. The first sample will be collected before the vaccination and the second one will be collected three weeks after the vaccination (If the patient is younger than 9 years old, the third sample will be collected three weeks after the booster vaccination). Titer of H1N1 influenza virus antibodies will be determined by hemagglutinin inhibition assay (HAI). A HAI titer with a 4-fold rise or greater is defined as seroconversion. Study subjects with seroconversion are regarded as responsiveness to the vaccination. We will analyze seroconversion rate as well. Meanwhile, if the patient presents influenza-like symptoms, we will perform throat swab or nasal swab for influenza rapid test, viral isolation, and novel H1N1 influenza PCR to confirm the diagnosis. After the study, we will be able to know whether or not current novel H1N1 influenza vaccination schedule is adequate and efficient for pediatric haemato-oncology patients.

Inclusion Criteria:

• Boys or girls aged ≧ 6 months old to 18 years old on the day of first vaccination;
• Subject and/or parents(s)/legal guardian(s) was willing to comply with planned study procedures and be available for all study visits;
• Subject was ever treated at pediatric haemato-oncology ward
• Subject and/or parents(s)/legal guardian(s) must read and signed the study-specific informed consent prior to initiation of any study procedure.

Exclusion Criteria:

• History of hypersensitivity to eggs or egg protein or similar pharmacological effects to study medication (AdimFlu-S (A/H1N1));
• Personal or family history of Guillain-Barré Syndrome;
• An acute febrile illness within the last 72 hours prior to vaccination;
• Subject with bleeding disorder or has any coagulation disorder that needs receipt of anticoagulants in the 3 weeks preceding inclusion contraindicating intramuscular injection;
• Subjects with influenza-like illness as defined by the presence of fever (temperature ≧38.5℃ ) and at least two of the following four symptoms: headache, muscle/joint aches and pains (e.g. myalgia/arthralgia), sore throat and cough;
• Female subjects who are pregnant, lactating or likely to become pregnant during the study; Women of childbearing potential disagree to use an acceptable method of contraception (e.g., hormonal contraceptives, IUD, barrier device or abstinence) throughout the study;
• Underlying condition in the investigator's opinion may be inappropriate for vaccination;

This study is designed to investigate the antibodies titers before and after the novel H1N1 influenza vaccination in pediatric haemato-oncology patients.