Factors associated with pregnant women's willingness to receive maternal pertussis vaccination in Guizhou Province, China: An exploratory cross-sectional study.

The rise in pertussis incidence among infants in Guizhou, China underscores the need for maternal acellular pertussis vaccine (aP) immunization, a key strategy in protecting infants from severe health consequences. However, the willingness of pregnant women in Guizhou to receive this vaccine is not well-understood. This study aimed to explore pregnant women's intentions toward maternal pertussis vaccination in Guizhou and identify the associated factors. A questionnaire based on the health belief model, was administered in an exploratory cross-sectional study from January to February 2022. Data from 564 participants were collected and analyzed. The chi-square test, Mann-Whitney U test, and Poisson regression were used to identify potential factors associated with vaccination intentions. Participants' median age was 27 y (interquartile range (IQR): 24-31), and the median number of children per participant was one. The study found that only 36.0% of the participants intended to receive the aP vaccine while 64.0% were uncertain or negative in this regard. Significant factors associated with intentions to vaccinate included perceived barriers and cues for action and perceived benefits. The major barriers for low vaccination intentions were safety concerns for both the fetus and the mother, and family members' negative attitudes. Free vaccines, perceiving preventive benefits, observing other pregnant women getting vaccinated, and healthcare provider recommendations may facilitate vaccination intentions. Multiple immune strategies should be developed or optimized to cope with the resurgence of pertussis.

Effects of contact tracing and nucleic acid testing on the COVID-19 outbreak in Zunyi, China: data-driven study using a branching process model.

BACKGROUND: During October 2021, China experienced localized outbreaks of COVID-19 in many cities. We analyzed the small local outbreak in Zunyi (Guizhou Province), a major city in southwestern China, and modeled the effects of different interventions on this outbreak. METHODS: Data on infections and contacts, provided by the Health Commission of Guizhou Province, were used to analyze the epidemiological characteristics of the outbreak and calculate the effectiveness of vaccination. A branching process model was used to simulate the outbreak. This model considered the time interval from exposure of the initial case to confirmation, the number of potential infections caused by the initial case, and the effects of the different interventions. RESULTS: From 18 to 25 October 2021, there were 12 patients with COVID-19 in Zunyi. Overall, the average age was 67.17 years-old, 8 patients were females, and 1 patient had an asymptomatic infection. The effectiveness of two-dose inactivated vaccine against SARS-CoV-2 infection was 16.7% (95% CI: 2.8% to 99.7%). The initial case was infected on 11 or 12 October 2021, 6.40 (95% CI: 6.37, 6.42; IQR: 4.92, 7.63) days before confirmation while the travelling in Lanzhou (Gansu Province). There were 10.07 (95% CI: 10.04, 10.09; IQR: 7.86, 11.93) potential secondary cases. When the effective vaccine coverage reached 60%, the probability of cumulative cases exceeding 20 was less than 8.77%, even if contact tracing was relaxed or eliminated. However, if the probability of tracing contacts decreased, earlier initiation of nucleic acid testing was necessary to control the outbreak. CONCLUSIONS: The COVID-19 outbreak in Zunyi was controlled quickly due to moderately effective vaccine coverage and rapid contact tracing. For controlling localized outbreaks, vaccination and contact tracing seemed to be more effective than massive nucleic acid testing in the initial phase of transmission. However, if there is low effective vaccine coverage or insufficient contact tracing, nucleic acid testing should start earlier.

Immunogenicity and safety of a live attenuated varicella vaccine in children 1-12 years of age: A randomized, blinded, controlled, non-inferiority phase 3 clinical trial.

OBJECTIVES: To evaluate the immunogenicity and safety of a live attenuated varicella vaccine produced using a cell factory process. METHODS: In this randomized, blinded, controlled, non-inferiority phase 3 clinical trial conducted in Guizhou, healthy children aged 1-12 years were randomly assigned in a 2: 1 ratio to receive one dose of experimental or control vaccine. Physical examination and first blood collection were performed preimmunization on day 0. Diary cards were collected after day 15. Contact cards and second blood samples were collected on day 30. The primary immunogenicity endpoint was the positive conversion rate of the anti-varicella virus antibody at 30 days postimmunization in susceptible children. Secondary endpoints were the fourfold increase rate, positive conversion rate, geometric mean titer, and geometric mean increase at 30 days after immunization in the total cohort. RESULTS: Of the 900 children assessed for eligibility, 894 received an experimental or control vaccine. Both the full analysis and safety analysis sets included 894 subjects. The seroconversion rate in the susceptible population was 95.84% in the experimental and 94.76% in the control group. The lower limit of the 95% confidence interval difference was -2.37%, which was greater than the non-inferiority margin set by the program (-10%). No significant difference in solicited adverse reactions was found between the groups. Within 6 months postimmunization, a total of 24 serious adverse events were reported, none related to the studied vaccine. CONCLUSION: The live attenuated varicella vaccine produced using a cell factory process was highly immunogenic, safe, and non-inferior to the product in the market. Further studies need to be implemented in the immune persistence, the epidemiological effectiveness and the rare adverse reactions.