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Methods for screening the naturally acquired and vaccine-induced immunity to the measles virus
1Department of Epidemiology, National Bacteriological Laboratory, Stockholm, Sweden.
Insights
The enzyme-linked immunosorbent assay (ELISA) accurately measures measles immunity post-vaccination, unlike the haemolysis-in-gel (HIG) test which shows discrepancies over time. ELISA provides reliable measles antibody level detection in children years after vaccination.
Area of Science:
- Immunology
- Vaccinology
- Public Health
Background:
- The measles, mumps, and rubella (MMR) vaccine was introduced in Sweden in 1982.
- Annual evaluations of immunity and seroconversion rates in 12-year-olds have been conducted since its introduction.
- Measles vaccination coverage in preschool children has been approximately 50% since 1977.
Purpose of the Study:
- To evaluate and compare the reliability of different serological assays for assessing measles immunity in children.
- To investigate the long-term antibody levels and immunity patterns following measles vaccination.
Main Methods:
- Two study groups were analyzed: 145 selected pre- and post-vaccination sera from schoolchildren (1986-1987) and 190 consecutive vaccinee sera (1988-1989).
- Assays used included the haemolysis-in-gel (HIG) technique, neutralization test (NT), and enzyme-linked immunosorbent assay (ELISA).
- Samples were tested for measles antibodies, comparing results between early and late post-vaccination periods.
Main Results:
- The NT and HIG tests showed congruent results in early post-vaccination sera but were discordant in late samples (up to 25% discrepancy).
- The ELISA assay consistently produced results congruent with the NT across all sample types.
- Both HIG and ELISA detected significantly lower antibody levels in late post-vaccination sera (8-11 years) compared to early samples or natural infection.
Conclusions:
- ELISA is a reliable method for assessing measles immunity, even in late post-vaccination samples, and correlates well with the gold standard NT.
- The HIG technique may underestimate measles immunity in the long term due to observed discordance with NT.
- Antibody levels wane over time after measles vaccination, highlighting the importance of accurate long-term monitoring methods like ELISA.
Abstract:
Since the measles, mumps and rubella (MMR) vaccine was introduced into Sweden in 1982, a yearly evaluation of the immunity patterns and sero-conversion rates in 12-year-old children has been carried out. Since 1977, about half of the pre-school children have been vaccinated against measles. This study includes two study groups. (1) 145 selected pre- and post-vaccination samples tested by the haemolysis-in-gel (HIG) technique and the neutralization test (NT). The selection was made from 1298 12-year-old schoolchildren in 1986 and 1987, whose pre-vaccination sera had shown negative or borderline reactions to the HIG technique. (2) Consecutive pre- and post-vaccination samples obtained from 190 vaccinees in 1988 and 1989. These samples were studied by an enzyme-linked, immunosorbent assay (ELISA) and compared to the NT. The NT and the HIG tests yielded congruent results in early post-vaccination sera from children susceptible to measles prior to vaccination. In late post-vaccination samples, the NT and the HIG tests were discordant, up to 25% of the NT-positive samples being negative by the HIG technique. In no instance did the ELISA produce discrepant results, compared with those of the NT. With both this assays significantly lower antibody levels were detected in late post-vaccination sera (8-11 years) compared to early post-vaccination samples (P less than 0.001) or to sera obtained after natural infection.