Varicella (chickenpox) is highly contagious among children and frequently breaks out in schools. In this study, we developed a dynamic compartment model to explore the optimal schedule for varicella vaccination in Jiangsu Province, China. A susceptible-infected-recovered (SIR) model was proposed to simulate the transmission of varicella in different age groups. The basic reproduction number was computed by the kinetic model, and the impact of three prevention factors was assessed through the global sensitivity analysis. Finally, the effect of various vaccination scenarios was qualitatively evaluated by numerical simulation. The estimated basic reproduction number was 1.831 ± 0.078, and the greatest contributor was the 5–10 year-old group (0.747 ± 0.042, 40.80%). Sensitivity analysis indicated that there was a strong negative correlation between the second dose vaccination coverage rate and basic reproduction number. In addition, we qualitatively found that the incidence would significantly decrease as the second dose vaccine coverage expands. The results suggest that two-dose varicella vaccination should be mandatory, and the optimal age of second dose vaccination is the 5–10 year-old group. Optimal vaccination time, wide vaccine coverage along with other measures, could enhance the effectiveness of prevention and control of varicella in China.

Background This study aims to investigate the epidemiologic characteristics and variational trends following a hepatitis B vaccine (HepB) inoculation programme carried out in children over the last 22 years in Jiangsu province. It also aims to evaluate the effect of hepatitis B vaccine immunisation and to analyse the influential of HBsAg positive carriers. Finally, the study also provides reliable data and a baseline for adjusting future prevention and intervention strategies in Jiangsu province. Methods The incidence rates of hepatitis B virus (HBV) in Jiangsu province from 2004 to 2014 were obtained from the National Notifiable Disease Reporting System (NNDRS). A stratified cluster random sampling method was used to select 3,002 subjects aged 1-29 years across 13 hepatitis B virus monitoring points throughout the province, which had been classified as either urban or rural. HBV was assessed from venous blood samples using Abbott microparticle enzyme immunoassay (MEIA) kits (Abbott Laboratories, Chicago, Illinois). Results HBV incidence in the 1-29 age group showed a significant downward trend since 2004 (P<0.001). Serological assessments showed that the prevalence values of the hepatitis B surface antigen (HBsAg) and hepatitis B core antibody (anti-HBc) in the 1-29 age group were 1.20% and 5.33%, respectively. And 66.89% tested positive for the hepatitis B surface antibody (anti-HBs). The HBsAg positive rate among participants was significantly lower in subjects who had been vaccinated than in those who had not (0.46% vs 14.93%, p<0.0001). Among persons who had received the full three-dose vaccine regimen, 90.93% received the first dose of the HBV vaccine within 24 hours of the baby’s birth. In this same group, the prevalence rates of HBsAg and anti-HBc were 0.05% and 0.95%, respectively, and the HBV infection rate decreased significantly after 2006. Conclusions The overall rate of Hepatitis B vaccinations and vaccinations administered within 24 hours of the baby’s birth have continuously improved since the HepB vaccine was integrated into the immunisation programme in Jiangsu province. Hepatitis B prevention and control works in the target population has achieved remarkable results.

Background This study aims to investigate the epidemiologic characteristics and variational trends following a hepatitis B vaccine (HepB) inoculation programme carried out in children over the last 22 years in Jiangsu province. It also aims to evaluate the effect of hepatitis B vaccine immunisation and to analyse the influential of HBsAg positive carriers. Finally, the study also provides reliable data and a baseline for adjusting future prevention and intervention strategies in Jiangsu province. Methods The incidence rates of hepatitis B virus (HBV) in Jiangsu province from 2004 to 2014 were obtained from the National Notifiable Disease Reporting System (NNDRS). A stratified cluster random sampling method was used to select 3,002 subjects aged 1-29 years across 13 hepatitis B virus monitoring points throughout the province, which had been classified as either urban or rural. HBV was assessed from venous blood samples using Abbott microparticle enzyme immunoassay (MEIA) kits (Abbott Laboratories, Chicago, Illinois). Results HBV incidence in the 1-29 age group showed a significant downward trend since 2004 (P<0.001). Serological assessments showed that the prevalence values of the hepatitis B surface antigen (HBsAg) and hepatitis B core antibody (anti-HBc) in the 1-29 age group were 1.20% and 5.33%, respectively. And 66.89% tested positive for the hepatitis B surface antibody (anti-HBs). The HBsAg positive rate among participants was significantly lower in subjects who had been vaccinated than in those who had not (0.46% vs 14.93%, p<0.0001). Among persons who had received the full three-dose vaccine regimen, 90.93% received the first dose of the HBV vaccine within 24 hours of the baby’s birth. In this same group, the prevalence rates of HBsAg and anti-HBc were 0.05% and 0.95%, respectively, and the HBV infection rate decreased significantly after 2006. Conclusions The overall rate of Hepatitis B vaccinations and vaccinations administered within 24 hours of the baby’s birth have continuously improved since the HepB vaccine was integrated into the immunisation programme in Jiangsu province. Hepatitis B prevention and control works in the target population has achieved remarkable results.