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Rotavirus infection in infants as protection against subsequent infections
F R Velázquez1, D O Matson, J J Calva
1Department of Infectious Diseases, Instituto Nacional de la Nutrición, Mexico City, Mexico.
Insights
Natural rotavirus infection in infants provides protection against future illness. Repeated infections increase immunity, reducing the risk and severity of rotavirus diarrhea.
Area of Science:
- Pediatrics
- Infectious Diseases
- Immunology
Background:
- Rotavirus is a primary cause of severe infant diarrhea.
- Evaluating natural infection's protective effects is crucial for vaccine assessment.
Purpose of the Study:
- To assess protection conferred by natural rotavirus infection in infants.
- To establish a baseline for rotavirus vaccine efficacy studies.
Main Methods:
- Longitudinal monitoring of 200 Mexican infants from birth to two years.
- Weekly home visits, stool collection, and physician assessment of diarrhea severity.
- Enzyme immunoassay, strain typing, and serum antibody (IgA, IgG) analysis.
Main Results:
- 316 rotavirus infections detected; 52% were primary, 48% were repeat.
- Progressively lower risks of infection and diarrhea with increasing prior infections.
- No moderate-to-severe diarrhea after two infections; subsequent infections were less severe.
Conclusions:
- Natural rotavirus infection induces protective immunity in infants.
- Protection escalates with each subsequent infection, mitigating diarrhea severity.
Background:
Rotavirus is the leading cause of severe diarrhea in infants. To provide a base line for assessing the efficacy of rotavirus vaccines, we evaluated the protection that is conferred by natural rotavirus infection.
Methods:
We monitored 200 Mexican infants from birth to two years of age by weekly home visits and stool collections. A physician assessed the severity of any episodes of diarrhea and collected additional stool specimens for testing by enzyme immunoassay and typing of strains. Serum collected during the first week of life and every four months thereafter was tested for antirotavirus IgA and IgG.
Results:
A total of 316 rotavirus infections were detected on the basis of the fecal excretion of virus (56 percent) or a serologic response (77 percent), of which 52 percent were first and 48 percent repeated infections. Children with one, two, or three previous infections had progressively lower risks of both subsequent rotavirus infection (adjusted relative risk, 0.62, 0.40, and 0.34, respectively) and diarrhea (adjusted relative risk, 0.23, 0.17, and 0.08) than children who had no previous infections. No child had moderate-to-severe diarrhea after two infections, whether symptomatic or asymptomatic. Subsequent infections were significantly less severe than first infections (P=0.024), and second infections were more likely to be caused by another G type (P=0.054).
Conclusion:
In infants, natural rotavirus infection confers protection against subsequent infection. This protection increases with each new infection and reduces the severity of the diarrhea.