Vaccination versus antibody screening for measles immunity in health care workers

To promote measles protection in community and health care facilities a law (Measles Protection act, MPA) came into force in Germany requiring documentation of two measles vaccinations or evidence of measles seropositivity for healthcare workers (HCW) born after 1970. The German Standing Committee on Vaccination extended this law to a recommendation of two measles, mumps, rubella (MMR) vaccinations. Our aim was to evaluate serology-based vaccination strategies for measles and to consider their extension to mumps and rubella.

Between 11/2020-7/2021, MMR serostatus was assessed in 386 HCW attending the Occupational Health Service Department for pre-employment or regular occupational examinations. Sociodemographic and documented vaccination data were collected.

Overall, measles IgG seropositivity was 72 %. Measles IgG was found in 77 %, 74 % and 61 % of employees with no, one and two documented measles vaccinations, respectively (p < 0.05). Seropositivity against MMR was detected in 66 % and 58 % with no and one documented measles vaccination, respectively. Considering measles immunity only anti-measles IgG screening prior vaccination saved costs. However, considering MMR seropositivity screening prior vaccination was not cost-effective. Measurement of measles virus neutralizing potency using a quantitative focus reduction neutralization assay to measure measles virus neutralizing potency indicated immunity in persons with two documented measles vaccine doses but negative or equivocal ELISA IgG results.

Measles seropositivity was below 75 % among HCW. In individuals with documentation of two measles vaccine doses ELISA tests underestimate protection, thus no serological testing is needed. Considering measles seropositivity in HCW with no or one documented measles vaccination, measles serological screening before vaccination was most cost-effective. However, aiming at MMR immunity, vaccination of HCW without serological screening was most cost-effective and offers important benefits that should not be dismissed.