A Prospective, Randomized, Double-Blind, Placebo-Controlled Trial to Assess the Safety and Tolerability of Influenza Virus Vaccine,(CAIV-T) in Healthy Infants

The objective of this study was to compare the safety and tolerability of one and two doses of influenza virus vaccine, trivalent, types A and B, live cold-adapted liquid (CAIV-T) with placebo when administered intranasally to healthy infants aged 6 < 24 weeks.

Inclusion criteria

• children at least 6 weeks of age and less than 24 weeks of age at the time of enrollment, of >37 weeks gestational age and with a birth weight of >2500 g, and in good health as determined by medical history, physical examination and clinical judgment;
• whose parent/legal guardian provided written informed consent after the nature of the study was explained;
• who, along with their parent or legal guardian, were available for the three month duration of the trial (from enrollment to study completion);
• whose parent(s)/legal guardian(s), could be reached by study staff for the post-vaccination contacts [telephone, clinic or home visit].

Exclusion criteria

• whose parents or legal guardians were perceived to be unavailable or difficult to contact for evaluation or study visits during the study period;
• with any serious chronic disease (e.g., with signs of cardiac or renal failure or severe malnutrition), including progressive neurological disease;
• with Down's syndrome or other known cytogenetic disorders;
• with a known or suspected disease of the immune system or those receiving immunosuppressive therapy, including systemic corticosteroids; or cytotoxic agents;
• who received any blood products, including immunoglobulin, in the period from birth through to the conclusion of the study;
• had an immunosuppressed or an immunocompromised individual living in the same household;
• with a documented history of hypersensitivity to egg or egg protein or any other component of the study vaccines or placebo;
• who were administered any live virus vaccine within one month prior to enrollment; or expected to receive another live vaccine within 1 month of vaccination in the study.
• for whom there was intent to administer any other investigational vaccine or agent from one month prior to enrollment through to the conclusion of the study;
• who received a dose of influenza treatment (commercial or investigational) two weeks prior to enrollment. The prophylactic use of influenza antivirals was not permitted;
• who, at anytime prior to study enrollment, received any influenza vaccine (commercial or investigational);
• with a respiratory illness with wheezing within two weeks prior to each dose of study vaccine;
• who received aspirin (acetylsalicylic acid) or aspirin-containing products in the two weeks prior to enrollment or for which use was anticipated during the study;
• with any medical conditions that in the opinion of the investigator might have interfered with interpretation of the study results.

Note: Pregnancy in any person who had regular contact with the subjects was not considered a contraindication to enrollment.