Dynamics of maternally transferred antibodies against measles, mumps, and rubella in infants in Sri Lanka.

BACKGROUND: Determining the dynamics of maternally transferred antibodies against measles, mumps, and rubella infections in infants is important for making evidence-based policy decisions regarding the timing of vaccination. METHODS: The levels of serum immunoglobulin G (IgG) developed against measles, mumps, and rubella infections were assessed using commercial ELISA kits in mother-newborn pairs (n = 294) and 6-12-month-old infants (n = 280) recruited from Colombo District, Sri Lanka. Antibody levels of mothers and their newborns were assessed with respect to sex and parity. Antibody levels and the protection conferred were assessed in a sample of infants who completed 6-12 months of age in relation to their age and sex. Antibody levels were compared between different age and sex groups using the Mann-Whitney U-test, and correlations of antibody titers were performed using the Spearman correlation test. RESULTS: The prevalence rates of seropositivity for measles, mumps, and rubella were 91.5%, 89%, and 88%, respectively, in mothers, and 95%, 91.5%, and 93%, respectively, in their newborns. The newborns had mean IgG levels exceeding those of the mothers (P < 0.001). Mothers with natural infections had higher antibody levels compared to vaccinated mothers, which resulted in a higher level of maternal transfer. All of the infants who were 9-10 months of age or older were seronegative for measles, all of those who were 10-11 months of age or older were seronegative for rubella, and all of those who were 11-12 months old were seronegative for mumps. CONCLUSIONS: The maternal transfer of antibodies to newborns is efficient and renders protection until the infants are 6-7 months old in the case of mumps and rubella and 7-8 months old in the case of measles. Hence infants remain vulnerable to infections before the first dose of the MMR vaccine.

The response to Typhi Vi vaccination is compromised in individuals with primary immunodeficiency.

Measurement of an individuals ability to respond to polysaccharide antigens is a crucial test to determine adaptive immunity. Currently the response to Pneumovax® is utilized but with the success of Prevnar®, measurement of the response to Pneumovax may be challenging. The aim of the study was to assess the response to Typhi Vi vaccination in both children and adult control groups and patients with primary immunodeficiency (PID). In the control groups, >95% of the individuals had pre Typhi Vi vaccination concentrations <100 U/mL and there was significant increase in concentration post Typhi Vi vaccination (p<0.0001) with>94% achieving ≥3 fold increase in concentration (FI). The response to Typhi Vi vaccination was significantly lower in both children (p = 0.006) and adult (p = 0.002) PID groups when compared to their control groups. 11% and 55% of the children and adult PID groups respectively did not obtain a response >3FI. There were no significant differences between the responses obtained in the children and adult PID groups. When all individuals with PID were separated into those with either hypogammaglobulinemia (HYPO) or common variable immunodeficiency (CVID), both groups had a significantly lower median FI than the control group (19, 95%CI 5-56 vs 59, 95%CI 7-237; p = 0.01 and 1, 95%CI 1-56 vs 32, 95%CI 5-136; p = 0.005). Further, a >3FI differentiated the antibody responses between both the CVID and HYPO groups and their control groups (AUC: 0.83, 95%CI: 0.65-1.00, p = 0.005 and 0.81, 95% CI: 0.65-0.97, p = 0.01). The data suggests that measurement of the response to Typhi Vi vaccination could represent a complementary assay for the assessment of the response to a polysaccharide vaccine.