Seroprevalence of IgG antibodies against measles, mumps and rubella in Swiss children during the first 16 months of life

Objective: To study the question of how long maternal IgG antibodies against measles, mumps and rubella persist in infants. Methods: Sera of children aged 0-16 months who had been hospitalised in our institution between 1994 and 1999 were identified from our routine serum collection. Exclusion criteria were: preterm delivery; suspected measles, mumps or rubella illness or exanthema of unknown aetiology; transfusion of blood products in the 6 months preceding serum collection; foreign-born mother; previous MMR immunisation. Ige antibodies were measured by use of commercially available ELISA kits. Results: 254 serum specimens were analysed. Age distribution of patients was as follows: 0-3 months II = 58; >3-6 months n = 48; >6-9 months n = 52; >9-12 months n = 42; >12-16 months n = 54. The following seroprevalence rates for IgG antibodies were found (measles/mumps/rubella): 0-3 months 97%/62%/91%; >3-6 months 40%/2%/42%; >6-9 months 4%/2%/10%; >9-12 months 2%/0%/ 12%; >12-16 months 0%/7%/7%. Conclusions: Our results demonstrate high levels of passive immunity against measles and rubella in Swiss infants during the first months of life, whereas immunity against mumps appears to be considerably less reliable. Beyond the first 3 months of life, IgG antibodies against all 3 illnesses are lacking in the majority of patients; beyond 12 months of age they are only rarely detectable. These results raise the question whether the first MMR immunisation, currently recommended at the age of 15 months in Switzerland, should be brought forward.