الملخص
Objective@#To investigate the characteristics of breakthrough cases of varicella in Haishu District, Ningbo City, Zhejiang Province from 2017 to 2022, so as to provide the evidence for varicella prevention and control.@*Methods@#Information on reported cases of varicella and vaccination in Haishu District from 2017 to 2022 were collected through the China Infectious Disease Reporting Management Information System and the Immunization Program Information Management System of Zhejiang Province. The breakthrough cases who had received 1 or 2 doses of varicella vaccine 42 days before the onset of disease were selected. The distribution of sex, age, region and the interval between onset and last immunization were descriptively analyzed.@*Results@#A total of 1 563 varicella cases were reported from 2017 to 2022. There were 928 breakthrough cases (59.37%), of which 660 cases with 1-dose immunization history (42.23%) and 268 cases with 2-dose immunization history (17.15%). The proportion of 1-dose breakthrough cases in total annual cases showed a decreasing trend (P<0.05) from 2017 to 2022, while there was no significant tendency on the proportion of cases with 2-dose immunization history (P>0.05). There were 392 males (59.39%) and 268 females (40.61%) with 1-dose immunization history. There were 150 males (55.97%) and 118 females (44.03%) with 2-dose immunization history. Breakthrough cases with 1- and 2- dose immunization history had an median age of 13.00 (interquartile range, 4.00) and 9.00 (4.00) years, respectively, and the difference was statistically significant (P<0.05). The regional distribution of the breakthrough cases with 1- and 2- dose immunization history was mainly in the rural-urban fringe, with 319 cases (48.33%) and 137 cases (51.12%), respectively, and the difference was statistically significant (P<0.05). The median interval between onset and last immunization was 12.00 (interquartile range, 3.00) and 4.00 (3.00) years, respectively, and the difference was statistically significant (P<0.05).@*Conclusions@# The breakthrough cases of varicella in Haishu District from 2017 to 2022 were mainly cases with 1-dose immunization history, males, and residents in rural-urban fringe. The age was older and the interval between onset and the last immunization was longer in cases with 1-dose immunization history than in cases with 2-dose immunization history.
الملخص
Objective@#To investigate the serum anti-mumps IgG antibody levels among children aged 0 to 4 years in Haishu District, Ningbo City, Zhejiang Province, so as to provide insights into improvements for mumps vaccination program.@*Methods@#Children aged 0 to 4 years were sampled from Haishu District using a stratified random sampling method in 2016 (before adjustment of the mumps vaccination program) and 2022 (after adjustment of the mumps vaccination program). Participants' demographics were collected using questionnaires, and the coverage of mumps-containing vaccines was collected from the Ningbo Municipal Immunization Information System. Serum anti-mumps IgG antibody was measured using enzyme-linked immunosorbent assay (ELISA), and the seroprevalence of anti-mumps IgG antibody and geometric mean concentration (GMC) were estimated among children aged 0 to 4 years in 2016 and 2022.@*Results@#A total of 464 children were enrolled in 2016, including 250 boys (53.88%) and 214 girls (46.12%), and there were 301 children receiving mumps-containing vaccines (64.87%). The seroprevalence of anti-mumps IgG antibody were 48.08%, 34.44%, 81.11%, 84.44% and 84.44%, and GMC were 233.86, 351.77, 333.66, 362.29 and 410.72 U/mL. A total of 456 children were recruited in 2022, including 236 boys (51.75%) and 220 girls (48.25%), and there were 427 children receiving mumps-containing vaccines (93.64%). The seroprevalence of anti-mumps IgG antibody were 72.73%, 95.00%, 100.00%, 98.68% and 99.04%, and GMC were 524.05, 1 229.69, 1 623.64, 788.01 and 738.41 U/mL. Higher seroprevalence and GMC of anti-mumps IgG antibody was seen in 2022 than in 2016 among children at all age groups (P<0.05).@*Conclusion@#Following adjustment for vaccination programs, the seroprevalence and GMC of anti-mumps IgG antibody significantly increased among children at ages of 0 to 4 years in Haishu District.