Reactogenicity to a live attenuated varicella vaccine in Canadian children
F Diaz-Mitoma1, S A Halperin, D Scheifele
1Children's Hospital of Eastern Ontario, Ottawa, Ontario. diaz@cheo.on.ca
Insights
This study found that a thermostable, high titre varicella vaccine was safe and well-tolerated in 504 healthy children aged one to 12 years. Most side effects were mild and temporary, with no serious adverse events reported.
Area of Science:
- Immunology
- Vaccinology
- Pediatrics
Background:
- Varicella (chickenpox) is a common viral illness, particularly in children.
- Vaccination is a key strategy for preventing varicella and its complications.
- Assessing the safety and reactogenicity of new vaccine formulations is crucial for public health.
Purpose of the Study:
- To evaluate the safety and reactogenicity of a novel thermostable, high titre varicella vaccine.
- To assess local and systemic adverse events following vaccination in a pediatric population.
Main Methods:
- An open-label study involving 505 healthy children aged one to 12 years.
- Participants received a single subcutaneous dose of the live attenuated varicella vaccine.
- Children were monitored for 42 days post-vaccination for adverse events.
Main Results:
- The varicella vaccine was generally well-tolerated, with most symptoms being mild and transient.
- Common local reactions included injection site pain, redness, and swelling.
- Mild systemic symptoms such as fever and varicella-like rashes were reported infrequently. No serious adverse events were observed.
Conclusions:
- The thermostable, high titre varicella vaccine demonstrated a favorable safety profile in healthy infants and children.
- The vaccine is considered well-tolerated, supporting its potential use in pediatric varicella prevention programs.
Objective:
To assess the reactogenicity and safety of a thermostable, high titre, varicella vaccine in healthy infants and children.
Design:
Open study of 505 children monitored for 42 days after vaccination.
Setting:
Three urban Canadian centres (Halifax, Ottawa and Vancouver).
Participants:
505 healthy children one to 12 years of age were enrolled and 504 completed the study. All were susceptible to varicella by history.
Interventions:
All participants received one dose of live attenuated varicella vaccine (1x10(4.5) plaque forming units/dose) subcutaneously.
Main Outcome Measures:
The children were monitored from the day of vaccine administration (day 0) until day 42. All local and general symptoms and signs were recorded on diary cards by the patients' parents, who were encouraged to fill in the cards on days 2 to 3 and 18 to 24 via telephone calls from study personnel.
Results:
Most of the symptoms noted after vaccine administration were mild and transient, and all resolved within the respective follow-up periods. Injection site symptoms included pain (17.5%, 13.9% and 30.4% in centres 1, 2 and 3 respectively), redness (21.1%, 32.1% and 48.8%) and swelling (7%, 10.3% and 29.2%). The general symptoms reported were fever 37.5 degrees C or higher (3.5%, 4.8% and 3.0%) and varicella-like rashes (6.4%, 2.4% and 0%). Two subjects had severe symptoms (one with cervical lymphadenopathy, and one with a fever higher than 39 degrees C) probably related to vaccine administration. No serious adverse events were reported during the entire study.
Conclusion:
The vaccine was well tolerated.
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