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Evaluation of cold-recombinant influenza A/Korea (CR-59) virus vaccine in infants
E L Anderson1, R B Belshe, B Burk
1Department of Medicine, Marshall University School of Medicine, Huntington, West Virginia 25755-9410.
Insights
This study found that intranasal influenza A/Korea (CR-59, H3N2) virus vaccination in infants showed dose-dependent infection rates. Maternal antibodies did not prevent vaccine virus replication in infants.
Area of Science:
- Virology
- Immunology
- Pediatrics
Background:
- Influenza A virus poses a significant public health threat, particularly to young children.
- Developing effective influenza vaccines for infants is crucial for disease prevention.
- Live cold-recombinant influenza virus vaccines offer a potential alternative to inactivated vaccines.
Purpose of the Study:
- To evaluate the infectivity and replication of a live cold-recombinant influenza A/Korea (CR-59, H3N2) virus vaccine in infants.
- To determine the dose-response relationship for intranasal vaccination in this age group.
- To assess the impact of maternal antibodies on vaccine virus replication.
Main Methods:
- Twenty-four infants aged 5-13 months received intranasal vaccination with varying doses (10^3.2 to 10^6.2 TCID50) of the CR-59 vaccine.
- Nineteen infants served as a control group.
- Infection rates and viral replication were monitored post-vaccination. Maternal antibody titers were also assessed.
Main Results:
- Infection rates increased with higher vaccine doses, with 50% infectivity occurring at 10^4.6 TCID50.
- Replication of the vaccine virus was observed in infected infants.
- Common post-inoculation symptoms like fever and respiratory illness occurred in both vaccinees and controls.
- Low-titer maternal antibodies did not inhibit vaccine virus replication.
Conclusions:
- The live cold-recombinant influenza A/Korea (CR-59, H3N2) virus vaccine demonstrated dose-dependent infectivity in infants.
- Further research is needed to optimize vaccine strategies for infants, considering factors like maternal antibodies.
Abstract:
Twenty-four infants 5 to 13 months of age were intranasally vaccinated with a live cold-recombinant influenza A/Korea (CR-59, H3N2) virus vaccine. Nineteen infants served as controls. The inocula ranged from 10(3.2) to 10(6.2) 50% tissue culture infective doses (TCID50) per infant. Zero of six, one of four, seven of ten, and four of four infants receiving 10(3.2), 10(4.2), 10(5.2), and 10(6.2) TCID50, respectively, were infected by the intranasal vaccine. The amount of virus required to infect 50% of infants was calculated to be 10(4.6) TCID50. The occurrence of fever, respiratory illness, and otitis media was common among both controls and vaccinees in the postinoculation period. Maternal antibody was present in low titers in some infants and did not inhibit replication of the vaccine virus.