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Clinical and epidemiological evaluation of a live, cold-adapted influenza vaccine for 3-14-year-olds
L G Rudenko1, N I Lonskaya, A I Klimov
1Department of Virology, Institute of Experimental Medicine, St. Petersburg, Russian Federation.
Insights
Live, cold-adapted (CA) influenza vaccines were safe and effective in children. This study demonstrated the efficacy of CA vaccines against influenza B virus infections, reducing disease incidence by 30-40%.
Area of Science:
- Immunology
- Virology
- Pediatrics
Background:
- Influenza poses a significant public health burden, particularly in pediatric populations.
- Development of effective and safe influenza vaccines is crucial for disease prevention.
- Live, cold-adapted (CA) reassortant vaccines offer a potential alternative to inactivated vaccines.
Purpose of the Study:
- To evaluate the safety, immunogenicity, and efficacy of live, cold-adapted (CA) reassortant influenza vaccines in children.
- To assess the impact of CA vaccines on influenza-like illness incidence in a large pediatric cohort.
- To demonstrate the efficacy of CA vaccine against influenza B virus infections.
Main Methods:
- Conducted controlled clinical and epidemiological investigations involving nearly 130,000 children aged 3-15 years.
- Administered live, cold-adapted (CA) reassortant mono-, di-, and trivalent influenza type A and B vaccines.
- Monitored vaccinees and a control group for 6 months, assessing clinical, immunological, and morbidity outcomes.
Main Results:
- Vaccines were well-tolerated, with transient febrile reactions in <1% of children.
- Type A reisolates were genetically stable, and reassortants did not suppress each other.
- Vaccination stimulated antibody responses to influenza A1, A3, and B strains, reducing influenza-like disease by 30-40%.
Conclusions:
- Live, cold-adapted (CA) reassortant influenza vaccines are safe and immunogenic in children aged 3-15 years.
- CA vaccines significantly reduced the incidence of influenza-like diseases in the vaccinated cohort.
- This study provides the first evidence of CA vaccine efficacy against influenza B virus infections.
Abstract:
Reported is a study of live, cold-adapted (CA) reassortant mono-, di-, and trivalent influenza type A and B vaccines in a series of controlled clinical and epidemiological investigations involving nearly 130 000 children aged 3-15 years. The results of clinical, immunological, and morbidity investigations of the vaccinees and a control group over 6-months' follow-up indicated that the vaccines were completely attenuated by the children. Transient febrile reactions occurred in < 1% of the children after vaccination, including double seronegative individuals with low antibody titres. The type A reisolates examined were genetically stable. The reassortants did not suppress each other after simultaneous inoculation of children and stimulated antibody response to influenza virus strains A1, A3, and B. The incidence of influenza-like diseases was approximately 30-40% lower among the vaccinated group than among the control group. The study demonstrates, for the first time, the efficacy of CA vaccine against infections caused by influenza B virus.