Evaluation of the adequacy of measles laboratory diagnostic tests in the era of accelerating measles elimination in Beijing, China

•1st adequacy evaluation of measles laboratory diagnostic tests in mainland China.•National diagnostic criteria would lead to missed measles diagnosis.•MCV immunization history lowered sensitivity of IgM tests and RT-PCR.•IgM test and RT-PCR should be combined for vaccinated cases and cases aged ≥15y. Measles-containing vaccine (MCV) was introduced in 1965 in Beijing and given to the children aged 8m–14y. In population-based surveillance system, real-time polymerase chain reaction (RT-PCR) and immunoglobulin M(IgM) serology tests have been conducted for each suspected case since 2013. We used the surveillance data to evaluate the adequacy of the tests for laboratory confirmation during 2014–2016. Informations on IgM tests, RT-PCR, age, vaccination history for confirmed cases were from the surveillance system. Laboratory confirmed cases were defined as cases with positive IgM serology and/or positive RT-PCR. All tests were conducted in the laboratories accredited by Beijing CDC or Beijing CDC laboratory. Totally 4600 cases were confirmed. Sensitivities of IgM tests within 0–3 days post rash, IgM tests within 4–28 days post rash and RT-PCR within 0–3 days post rash were 56.53%, 82.06% and 94.39%, respectively. The combined sensitivity of IgM tests and RT-PCR decreased by the interval between rash onset and collection of virologic specimen. MCV immunization history lowered sensitivity of IgM tests and RT-PCR. Among the cases aged ≥ 15 years, around 95% had no written immunization records. The sensitivity of IgM tests within 0–3 days post rash was less than 60%. Around 60% had unknown immunization histories. Compared with unvaccinated cases based on written records, unvaccinated cases based on recollection had no significantly different sensitivity of laboratory tests. But unknown immunization history significantly lowered sensitivity of RT-PCR within 0–3 days post rash. Neither IgM tests nor RT-PCR reached 100% sensitive for confirmed cases. Virologic specimen should be collected as early as possible to achieve maxim sensitivity. Cases with unknown immunization history could not be treated as unvaccinated. Combination of the two tests and further laboratory assays were needed especially for vaccinated cases or cases aged ≥15 years.