To monitor the safety of Shanghai Institute of Biological Products Company's influenza vaccine in subjects aged 3 years and older through Adverse Events Following Immunization Surveillance System of China.

The hypothesis is that there is no significant difference in the occurrence of adverse events among influenza vaccines manufactured by SIBP and other companies.

Inactivated split-virion vaccines from Shanghai Institute of Biological Products Company have been used for more than 10 years in Beijing population. Some 160 thousands doses have been sold to subjects aged 3 years and older in this area. We review and summarize spontaneously reported adverse events from safety surveillance.

Adverse events were collected through the Adverse Events Following Immunization (AEFI) Surveillance System. Beijing CDC and local prefectural CDC must organize an expert panel to investigate adverse events and assess causality, using criteria based on Chinese Standard Procedures for Vaccination. The panels consist of physicians, epidemiologists, pharmacists, and other relevant experts. In general, expert panels investigate deaths, life-threatening illnesses, and permanent disabilities, and immunization-program managers or vaccination providers investigate common, minor adverse events. Adverse events are classified into one of five categories: vaccine reactions (common and minor to rare and more serious), program errors, coincidental illnesses, psychogenic reactions, and unclassifiable events.

At the time of vaccination, vaccinees were instructed to report any adverse event to physicians or vaccination providers. The following adverse events were required to be reported: adverse events that were fatal or that resulted in disability and clusters of events (i.e., notably high numbers of similar adverse events related to a certain vaccine) ; anaphylaxis or other allergic reactions occurring within 24 hours after vaccination; fever (axillary temperature, >37.5°C), angioedema, or a local injection-site reaction (diameter, >2.5 cm) occurring within 5 days after vaccination; purpura, an Arthus reaction, febrile convulsion, seizure, or polyneuritis occurring within 15 days after vaccination; and the Guillain-Barré syndrome occurring within 3 months after vaccination. Other reactions that were common and minor (e.g., mild pain and fatigue) were not required to be reported.

Inclusion Criteria:

• Males and females aged 3 years and above on the day of immunization, who are eligible for seasonal influenza vaccination.
• Recipients of SIBP's inactivated, split-virion influenza vaccine.

Exclusion Criteria:

• History of any serious reaction to flu vaccine, or any materials in the vaccine, and to eggs (including ovalbumin) and chicken protein.
• Receipt of a live vaccine within 4 weeks prior to Study Day 1.
• Any condition, which in the opinion of the study doctor, might interfere with the evaluation of the study objective.

Beijing subjects aged 3 years or older, at the time of routine visit to a participating clinic or hospital for influenza vaccination.