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Trial of Edmonston-Zagreb measles vaccine in infants aged under nine months
V Pongrithsukda1, R Gluck, S Suwatanapongched
1Department of Pediatrics, Maharaj Nakhon Ratchasima Hospital, Thailand.
Insights
Early measles vaccination with the Edmonston-Zagreb strain in infants under nine months demonstrated an 89% seroconversion rate. This approach shows promise for reducing measles incidence in developing countries.
Area of Science:
- Pediatrics
- Immunology
- Vaccinology
Background:
- Maternal measles antibodies wane before nine months in many infants in developing nations.
- This antibody loss increases susceptibility to measles in endemic regions.
- Current vaccination schedules may not provide adequate protection during this vulnerable period.
Purpose of the Study:
- To evaluate the immunogenicity and safety of the Edmonston-Zagreb measles vaccine strain in infants younger than nine months.
- To assess the potential of early infant immunization to reduce measles incidence in high-risk populations.
Main Methods:
- A clinical trial involving 45 infants with a mean age of 25 weeks.
- Administration of a single dose of the Edmonston-Zagreb measles vaccine.
- Measurement of antibody levels via plaque neutralization test pre-vaccination and at a mean age of 38 weeks.
Main Results:
- An 89% seroconversion rate was observed post-vaccination.
- Only 4.4% of infants possessed pre-existing immunity.
- Reported adverse reactions (fever, rhinorrhea, rash, local reactions) were mild and resolved spontaneously, affecting 33.33% of infants.
Conclusions:
- The Edmonston-Zagreb measles vaccine is effective and safe for infants under nine months of age.
- Early vaccination with this strain offers a viable strategy to combat measles in vulnerable infant populations.
- Findings support the potential for adjusting vaccination schedules in endemic areas to improve disease control.
Abstract:
Due to the recent finding that most infants in developing countries have lost maternal antibody for measles before nine months of age, immunization of infants younger than the recommended age of nine months would help reducing the incidence of measles in these endemic areas. We conducted a trial of Edmonston-Zagreb measles vaccine which is the strain that may be more immunogenic in young infants than the widely used Schwarz strain. Forty-five infants with mean age of 25 weeks received a dose of Edmonston-Zagreb vaccine. Antibody levels were measured, using plaque neutralization test, before and about 3 months after vaccination at which mean age was 38 weeks. The seroconversion rate was 89%. Only two infants (4.4%) had immunity before vaccination. Fifteen infants (33.33%) reported some adverse reactions including fever (13.33%), rhinorrhea (8.89%), rash (4.44%) and local reactions (22.22%). All of the reactions resolved spontaneously. We conclude that Edmonston-Zagreb measles vaccine is efficacious and safe in infants aged under nine months.