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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

A measles outbreak in a middle school with high vaccination coverage and evidence of prior immunity among cases, Beijing, P.R. China.

BACKGROUND: Age-appropriate receipt of ≥ 2 measles-containing vaccine (MCV) doses has been considered evidence of immunity against measles. Transmission of measles is rarely reported among such persons. METHODS: We report a measles outbreak in a middle school in Beijing that has high coverage with ≥ 2 documented MCV doses. History of previous measles and documentation of MCV receipt were collected for all individuals. Cases were identified by active surveillance and confirmed by laboratory tests. Measles immunoglobulin G (IgG) titers and clinical presentations were obtained for each case. RESULTS: Of 1331 individuals without a prior history of measles, 1172 (88.1% [95%CI:86.4-91.5%]) and 1078 (81.0% [95%CI:78.9-83.1%]) had age-appropriate receipt of ≥ 2 MCV doses by domestic and U.S. CDC/ACIP criteria, respectively. Thirteen measles cases occurred in the outbreak. The index case and 3 secondary cases were students. The 9 tertiary cases included 2 teachers and 7 students. All 11 student cases received ≥ 2 age-appropriate MCV doses by Chinese domestic criteria; 8 were age-appropriately vaccinated by U.S. CDC/ACIP criteria. Measles IgG was detected during the acute phase of measles for all but 2 cases -the first case and 1 tertiary case. Among students with age-appropriate receipt of ≥ 2 MCV doses, the length of time since the last MCV was significantly associated with risk of measles: for the 1172 students, the risk was 4.6 [OR5.6;95%CI:1.4-22.9] and 5.5 [OR6.5;95%CI:1.4-29.8] times higher when the last MCV dose was 5-9 years and ≥ 10 years prior, respectively, compared with <5 years prior; for the 1078 students, the risk was 4.1 [OR5.1;95%CI:1.3-20.7] times higher when the last MCV dose was 5-9 years prior compared with <5 years prior. CONCLUSIONS: This is the first report from China showing measles transmission among persons with prior evidence of immunity. Secondary vaccine failure may have played an important role in measles transmission. Further laboratory surveillance is needed to assess the persistence of vaccine-induced immunity of domestically-produced MCV in China.

[Analysis on the imported measles cases in Beijing, 2014].

OBJECTIVE: To analyze the imported measles cases who came to Beijing seeking for better medical services and to explore the feasible strategies for prevention and control of the situation. METHODS: Descriptive analysis was conducted for all the measles cases noted from the Measles Surveillance System, between January 1, 2014 and December 31, 2014. RESULTS: 3 328 measles cases were reported in Beijing, including 2 397 (2 397/3 328, 72.0%) native residents and 931 (931/3 328, 28.0%) came from other provinces. Peak of the imported cases appeared earlier than those native cases, with 934 cases (934/2 397, 39.0%) having had hospital exposure 7-21 days prior to the onset of the disease. Majority of the imported were children, including 718 of them (718/931, 77.1%) under the age of 15. Most cases were reported from 3 infectious disease hospitals (567/1 156 person-time, 49.0%) and 2 children's hospitals (445/1 156 person-time, 38.5%). Original addresses of the imported cases distributed in 24 provinces, with 705 of them (705/931, 75.7%) coming from Beijing's neighboring province (Hebei). Clinic symptoms with epidemiological information were analyzed on 712 cases. 704 cases (704/712, 98.9%) presented rash at home town while another 621 cases (621/712, 87.2%) developed rash 4 days after arriving in Beijing and were still in the infectious period. CONCLUSION: There was a big amount of imported measles cases in Beijing that called for the elimination of the disease in a urgent phase. It is necessary to timely develop and conduct targeted prevention and control measures on the disease in Beijing.

[Safety and epidemiological effects of the first China-made mass A (H1N1) influenza vaccination].

OBJECTIVE: To evaluate the safety and epidemiological effects on the first mass vaccination program, using the China-made A (H1N1) influenza vaccine. METHODS: Descriptive epidemiology and cohort study design were used to assess the influenza A H1N1 vaccine on its safety and epidemiological effects. RESULTS: 95 244 subjects were immunized with A (H1N1) influenza vaccine. 193 adverse events were reported through AEFI Management System, with the Reported rates of AEFI as 2.03‰. Most of the adverse events (137/193, 71.0%) happened during the first 24 hours after immunization was carried out. Of 81 adverse reactions confirmed to be related to immunization, with 78 (96.3%) showed mild reactions. No Guillain-Barre Syndrome related to vaccination was reported through the AEFI Management System. The epidemiological protection rate of A (H1N1) vaccine could reach 80.9% when the coverage was not considered. CONCLUSION: The A (H1N1) influenza vaccine showed a similar safety profile to seasonal flu vaccine. The vaccine demonstrated a good epidemiological effects against A (H1N1) influenza virus infection.

Safety and effectiveness of a 2009 H1N1 vaccine in Beijing.

BACKGROUND: After the first monovalent 2009 pandemic influenza A (H1N1) vaccine became available in September 2009, Chinese officials conducted a mass vaccination program in Beijing. We evaluated the safety and effectiveness of the vaccine. METHODS: During a 5-day period in September 2009, a total of 95,244 children and adults received the PANFLU.1 vaccine (Sinovac Biotech), a monovalent split-virion vaccine of 15 µg of hemagglutinin antigen without adjuvant. We assessed adverse events after immunization through an enhanced passive-surveillance system and through active surveillance, using diary cards and telephone interviews. Active surveillance for neurologic diseases was implemented in hospitals citywide. To assess vaccine effectiveness, we compared the rates of reported laboratory-confirmed cases of 2009 H1N1 virus infection in students who received the vaccine with the rates in those who did not receive the vaccine, starting 2 weeks after the mass vaccination. RESULTS: As of December 31, 2009, adverse events were reported by 193 vaccine recipients. Through hospital-based active surveillance, 362 cases of incident neurologic diseases were identified within 10 weeks after the mass vaccination, including 27 cases of the Guillain-Barré syndrome. None of the neurologic conditions occurred among vaccine recipients. From 245 schools, 25,037 students participated in the mass vaccination and 244,091 did not. During the period from October 9 through November 15, 2009, the incidence of confirmed cases of 2009 H1N1 virus infection per 100,000 students was 35.9 (9 of 25,037) among vaccinated students and 281.4 (687 of 244,091) among unvaccinated students. Thus, the estimated vaccine effectiveness was 87.3% (95% confidence interval, 75.4 to 93.4). CONCLUSIONS: Among 95,244 children and adults in Beijing, the PANFLU.1 vaccine had a safety profile similar to those of seasonal influenza vaccines and appeared to be effective against confirmed H1N1 virus infection in school-age children. (Funded by the Beijing Municipal Health Bureau.).