Background: The aim of this study was to investigate the immunogenicity and safety of the enterovirus 71 vaccine (EV71 vaccine) administered alone or simultaneously. Methods: A multi-center, open-label, randomized controlled trial was performed involving 1080 healthy infants aged 6 months or 8 months from Shandong, Shanxi, Shaanxi, and Hunan provinces. These infants were divided into four simultaneous administration groups and EV71 vaccine separate administration group. Blood samples were collected from the infants before the first vaccination and after the completion of the vaccination. This trial was registered in the Clinical Trials Registry (NCT03519568). Results: A total of 895 were included in the per-protocol analysis. The seroconversion rates of antibodies against EV71 in four simultaneous administration groups (98.44% (189/192), 94.57% (122/129), 99.47% (187/188) and 98.45% (190/193)) were non-inferior to EV71 vaccine separate administration group (97.93% [189/193]) respectively. Fever was the most common adverse event, the pairwise comparison tests showed no difference in the incidence rate of solicited, systemic or local adverse events. Three serious adverse events related to the vaccination were reported. Conclusions: The evidence of immunogenicity and safety supports that the EV71 vaccine administered simultaneously with vaccines need to be administered during the same period of time recommended in China.

Rubella occurs worldwide, causing approximately 100,000 cases annually of congenital rubella syndrome, leading to severe birth defects. Better targeting of public health interventions is needed to achieve rubella elimination goals. To that end, we measured the epidemiological characteristics and seasonal dynamic patterns of rubella and determined its association with meteorological factors in Shaanxi Province, China. Data on rubella cases in Shaanxi Province from 2005 to 2018 were obtained from the Chinese National Notifiable Disease Reporting System. The Morlet wavelet analysis was used to estimate temporal periodicity of rubella incidence. Mixed generalized additive models were used to measure associations between meteorological variables (temperature and relative humidity) and rubella incidence. A total of 17,185 rubella cases were reported in Shaanxi during the study period, for an annual incidence of 3.27 cases per 100,000 population. Interannual oscillations in rubella incidence of 0.8–1.4 years, 3.8–4.8 years, and 0.5 years were detected. Both temperature and relative humidity exhibited nonlinear associations with the incidence of rubella. The accumulative relative risk of transmission for the overall pooled estimates was maximized at a temperature of 0.23°C and relative humidity of 41.6%. This study found that seasonality and meteorological factors have impact on the transmission of rubella; public health interventions to eliminate rubella must consider periodic and seasonal fluctuations as well as meteorological factors.

To determine the estimated pertussis incidence in adults and the need for a booster dose by detecting pertussis and diphtheria antibody levels in adults in Shaanxi province, China. Blood samples were collected from healthy individuals aged 18–59 years in Shaanxi province in 2017. Serum immunoglobulin G (IgG) antibodies against pertussis toxin (PT) and diphtheria toxin (DT) were determined using enzyme-linked immunosorbent assay. The data on reported pertussis cases in Shaanxi province were collected from the China Information System for Disease Control and Prevention and compared with the results of this study. A total of 4307 subjects were enrolled. The mean concentration of anti-PT IgG was 19.6 IU/mL (95% CI = 18.9–20.3), and the positive rate (≥40 IU/mL) was 11.0% (474/4307), of which recent infections (≥100 IU/mL) accounted for 1.2% (53/4307). Only one adult case of pertussis was reported in 2017, which is much lower than the results of this study. The mean concentration of anti-DT IgG was 0.04 IU/mL (95% CI = 0.04–0.05), and the positive rate (≥0.01 IU/mL) was 82.3% (3543/4307). The mean concentration of anti-DT IgG decreased from 0.07 IU/mL in the 18–29 year-old group to 0.03 IU/mL in the 50–59 year-old-group, and the positivity rate decreased from 86.7% to 78.7%. Our study suggests that pertussis is not uncommon among adults. The existing surveillance system might have underestimated the true incidence of pertussis. The diphtheria antibody levels decreased with age. Booster vaccination against pertussis should be considered for adolescents and young adults.

To better understand the impact of COVID-19 epidemic on routine vaccination, a cross-sectional study was carried out during non-pharmaceutical intervention period (2020) and mass COVID-19 vaccination period (2021) in Shaanxi province. Data on NIP (National Immunization Program, Free), nNIP (non-National Immunization Program, Paid), and COVID-19 vaccines inoculated and vaccination clinics were collected. At the beginning of the COVID-19 epidemic, the rate of routine vaccination clinics providing vaccination services was only 20.0%, rabies vaccination clinics was 89.9% and obstetric vaccination clinics was 95.9%. Compared with 2019 (as baseline), NIP vaccines inoculated in 2020 and 2021 decreased by 3.5% and 19.2%, respectively, on the contrary, nNIP vaccines increased by 25.8% and 34.7%, respectively. In 2021, 74.9% of vaccination clinics were involved in mass COVID-19 vaccination, and there was not a significant impact of mass COVID-19 vaccination on the number of other vaccines inoculated. Vaccination coverage of all NIP vaccines was not different from that in previous years. COVID-19 epidemic had a short-term impact on routine vaccination at beginning. The impact of mass COVID-19 vaccination on routine vaccination could even be ignored. The COVID-19 epidemic has once again made people realize the great harm of infectious diseases, and has improved everyone's willingness to receive routine vaccines.

Mumps is an acute infectious disease, which was well controlled in the past, but recently it has resurged in some areas. This study aimed to evaluate the safety profile of the live attenuated mumps vaccine after large-scale vaccination. We conducted an observational, open-label phase 4 trial in Shaanxi, China from October 2020 to March 2021. Eligible participants were freshmen of junior high school who were not above 14 years old. Adverse events following immunization (AEFI) monitoring was carried out by active and passive surveillance. Safety follow-ups were conducted during the study participation. Overall, 10057 subjects were enrolled in the active surveillance analysis. A total of 214 subjects reported adverse reactions with an incidence of 2.13% (214/10057). Most adverse reactions were grade 1, and the incidence of grade 1 adverse reactions was 1.44% (145/10057); 0.60% for grade 2 (60/10057); and 0.09% for grade 3 (9/10057). The majority of adverse reactions were solicited (1.73%, 174/10057). Injection-site pain was the most frequently reported local adverse reaction (0.71%, 71/10057), followed by redness (0.29%, 29/10057). The most common systemic adverse reactions were nausea (0.19%, 19/10057) and fever (0.16%, 16/10057). For passive AEFI surveillance, 57 AEFI cases were reported, with an incidence of 19.28/100000 (57/287608). And most AEFI cases were common adverse reactions (66.67%, 38/57). In total, the live attenuated mumps vaccine evaluated in this trial has a favorable safety profile and can be used for large-scale inoculation.

Objective: In developing countries, combined vaccine availability remains limited due to economic constraints, healthcare infrastructure, and supply chain challenges. While some imported combined vaccines are available in China, their accessibility is restricted. Co-administration of individual vaccines presents a viable alternative. This study evaluates the immunogenicity and safety of simultaneous sIPV and DTaP administration to support vaccination policies and improve immunization rates.Methods: In this randomized, controlled, open-label, multicenter non-inferiority trial, 702 healthy 3-month-old infants from Shaanxi, Shanxi, and Hebei provinces were enrolled and assigned to three groups: Group 1 (sIPV + DTaP co-administration), Group 2 (sIPV alone), and Group 3 (DTaP alone). Vaccines were administered on a 3-4-5-month schedule. Serum samples were collected pre-vaccination and 30 days post-vaccination to assess antibody responses. Adverse events (AEs) were monitored for safety evaluation.Results: Among 671 infants completing the study (642 per protocol), co-administration (Group 1) demonstrated non-inferior immunogenicity compared to separate administration. Seroconversion rates and geometric mean titers (GMTs) for poliovirus types 1,2 and 3 were comparable between Groups 1 and 2. For anti-PT, FHA, D, T, Group 1 showed non-inferiority to Group 3 in seroconversion. However, anti-PT and anti-FHA geometric mean concentrations (GMCs) were lower (Group 1:anti-PT 31.06 [95% CI: 28.56–33.77], anti-FHA 29.40 [27.68–31.24]; Group 3: anti-PT 39.32 [36.25–42.65], anti-FHA 33.06 [31.01–35.24]). No significant differences were observed in anti-D and anti-T GMCs. AE rates were similar across groups, with local reactions (e.g., induration) more frequent in Group 1 (6.84%) than in Group 2 (0.85%). Systemic AEs (primarily grade 1–2 fever) did not differ significantly.Conclusion: Co-administration of sIPV and DTaP is immunogenically non-inferior to separate administration and demonstrates comparable safety. This strategy is feasible and may support simplified immunization schedules in China.Clinical trial registration: ClinicalTrials.gov, identifier NCT04053010.