Discussion
mumps, pain
ADVERSE REACTIONS, HAND INFECTION, ADVERSE EVENTS, MUMPS, MUMPS, COMPLICATIONS
Mumps has become a public health problem due to the global resurgence among adolescents in recent years. In order to ensure long-lasting immunity against mumps, the WHO has recommended the introduction of a second dose of mumps-containing vaccine. In China, MMR vaccine has been included in immunization program since 2008 and almost all children receive by now a single dose of MMR at 18 months of age. The live attenuated mumps vaccine (S79 strain) produced by Sinovac (Dalian) Vaccine Technology Co., Ltd. vaccine was approved for marketing in China in 2016 and an extensive post-marketing safety assessment in the context of large-scale applications was necessary. In this study, this vaccine was tested as a booster immunization in China: a combination of active surveillance and passive surveillance were used to evaluate the safety of post-vaccination and a good safety profile was demonstrated.Our study showed that the overall incidence of adverse reactions was 2.13%, which was significantly lower than the 18.5% in a previous booster immunization trial [In accordance with the present findings, most of the solicited local and systemic adverse reactions caused by the mumps vaccine were mild or moderate in intensity, and the participants recovered without any complications. A few grade 3 adverse reactions were reported, the incidence of which was less than 1%. These data, together with the fact that no serious adverse events were reported throughout the trial, indicated a favorable safety profile for the investigational vaccine in this trial. Injection-site pain was the most common local symptom, which was consistent with other published clinical studies [A previous clinical trial indicated that adverse reactions to the live attenuated mumps-containing vaccine mainly occurred within 3 days after vaccination [In the current study, the incidence of AEFI in passive surveillance was 19.28/100000, which was significantly lower than that in active surveillance. Similar phenomena were also observed in post-marketing studies of other vaccines [One of the strengths of this study was that the safety data were collected by a combination of active surveillance and passive surveillance. We knew that safety monitoring in post-licensure surveillance mainly relies on passive reporting systems and epidemiological research, while our study could perform a comprehensive safety evaluation. However, this study also has some limitations. First, previous data on mumps vaccination and infection were not collected. There has been previous evidence that the incidence of adverse events after MMR vaccination in adults may be related to whether or not subjects had received MMR in childhood [To conclude, this phase 4, open-label, observational trial showed that the live attenuated mumps vaccine produced by Sinovac (Dalian) was generally safe, well-tolerated and suitable for large-scale inoculation.