ABSTRACT
Objective@#To evaluate the effectiveness of varicella vaccine in varicella outbreaks and to analyze the influencing factors, and to provide a reference for making the targeted prevention and controlling measures.@*Methods@#A total of 3 888 students with no history of varicella were selected from 2 schools with varicella outbreak in Guangdong Province in 2021, a retrospective cohort study was conducted by using questionnaire survey, rate ratio ( RR ) and vaccine effectiveness ( VE ) values were calculated and Logistic regression was uses to analyze the factors influencing the protective effect of varicella.@*Results@#There were 138 confirmed cases of varicella among the participants. There was no significant sex difference in the vaccination rate( χ 2=1.36, P =0.51), but there was significant difference in the vaccinattion rate of different age groups( χ 2=555.82, P <0.01). The overall protective effect of VarV was 66.94%(95% CI =56.17%-77.71%), and the protective effect of 2 doses of vaccine( VE = 90.02% , 95% CI =83.13%-96.90%) was higher than that of 1 dose( VE =49.40%, 95% CI =32.36%-66.44%)( χ 2=24.93, P < 0.01 ). The high fever rates in the vaccinated and unvaccinated groups were 7.69% and 25.81%, with significant difference( χ 2= 6.29 , P <0.05). The rates of moderate and severe skin lesions of vaccinated and unvaccinated groups was 20.00% and 50.00%, respectively, and the difference was statistically significant( χ 2=11.32, P <0.01). The protective effects of varicella vaccine against high fever and moderate to severe rash were 70.19%(95% CI =42.11%-98.27%) and 60.00%(95% CI =38.15%-81.85%). Stratified analysis showed that there were significant differences in different years of vaccination( χ 2=37.87, P <0.05), while there were no significant differences in age of vaccination and vaccine manufacturer ( P >0.05).@*Conclusion@#Varicella vaccination can prevent chickenpox infection and reduce the severity of the disease. However, the efficacy of varicella vaccine was affected by vaccination years. It is recommended to improve the vaccination coverage of varicella vaccine to prevent the outbreak of the epidemic.
ABSTRACT
The elucidation of vapor-liquid equilibrium (VLE) of the halogenated silane was necessary for the production of silicon derivatives, especially for methylvinyldichlorosilane, due to the lack of the relevant reports. Isobaric VLE for the system methyldichlorosilane-dimethyldichlorosilane-benzene and isobaric VLE of the three binary systems were measured with a new pump-ebulliometer at the pressure of 101.325 kPa. These binary compositions of the equilibrium vapor were calculated according to the Q function of molar excess Gibbs energy by the indirect method and the resulted VLE data agreed well with the thermodynamic consistency. Moreover, the experimental data were correlated with the Wilson, NRTL, Margules and van Laar equations by means of the least-squares fit, the acquired optimal interaction parameters were fitted to experimental vapor-liquid equilibrium data for binary systems. The binary parameters of Wilson equation were also used to calculate the bubble point temperature and the vapor phase composition for the ternary mixtures without any additional adjustment. The predicted vapor-liquid equilibrium for the ternary system was in a good agreement with the experimental results. The VLE of binary and multilateral systems provided essential theory for the production of the halogenated silane.
ABSTRACT
This paper describes measurement of vapor-liquid equilibrium (VLE) data of methyldichlorosilane-methyltrichlorosilane-dimethyldichlorosilane system and that of the three binary systems at 101.325 kPa with a new pump-ebulliometer. The equilibrium composition of the vapor phase was calculated from pTx by indirect method. The model parameters of the liquid activity coefficient of the Wilson, NRTL, Margules and van Laar equations was corrected by the least square method. The ternary system VLE data were predicted by the Wilson equation, with the calculated boiling points showing good agreement with the experimental data.