ABSTRACT
Background Research on the relationship between ambient temperature and preterm birth has received increasing attention, but the conclusions of the previous literature are inconsistent. Objective To explore the impact of environmental temperature exposure in Ningbo on premature delivery of pregnant women. Methods The birth information, preterm birth data, and age of pregnant women from January 2016 to September 2020 were collected by the electronic medical record system of Ningbo Women’s and Children’s Hospital. Meteorological data for the same period were obtained through Ningbo Meteorological Bureau, including daily average temperature, daily average relative humidity, and daily average air pressure. Daily concentrations of SO2, NO2, and PM10 were derived through the air quality real-time release system on the website of Ningbo Environmental Protection Bureau. A distributed lag nonlinear model was used to analyze the impact of environmental temperature on preterm birth by stratifying pregnant women’s age and birth delivery mode. Results The incidence rate of preterm birth in Ningbo from 2016 to 2020 was 5.91%. The exposure-response curve between environmental temperature and preterm birth presented a “U” shape. Taking 22.5 ℃ as a reference, the cumulative effect of 31 ℃ (the 95th percentile) and 32 ℃ (the 99th percentile) over a 21-day lag on preterm delivery was statistically significant, and the related RR (95%CI) values were 1.67 (1.05-2.65) and 1.85 (1.09-3.14) respectively. The results of stratified analysis showed that among pregnant women ≥30 years old, the 21-day cumulative effects of 31 ℃ and 32 ℃ on preterm delivery were statistically significant, and the related RR (95%CI) values were 2.09 (1.08-4.05) and 2.36 (1.11-5.03) respectively; among pregnant women with natural delivery, the 21-day cumulative effect of 32 ℃ on preterm delivery was statistically significant, and the RR (95%CI) was 1.95 (1.02-3.74). Conclusion Exposure of pregnant women to high temperature during pregnancy could increase the risk of preterm birth, and there is a delayed cumulative effect.
ABSTRACT
<p><b>OBJECTIVE</b>To evaluate the breakthrough varicella infection rate and varicella vaccine effectiveness (VE) among children who received 1-dose varicella vaccine.</p><p><b>METHODS</b>A total of 57 180 subjects for the consecutive 4-year birth cohorts were selected from the local children born between 2007 and 2010 in Yinzhou District, Ninghai County and Yuyao City. And they were followed up for varicella from 2008 to 2013. The recipients of the vaccinations were identified through Ningbo Immunization Information System and data on breakthrough infections among the recipients were collected by using China Information System for Disease Control and Prevention. The breakthrough varicella rate and the VE were calculated and the trends of them were described from 2008 to 2013 among 4-year birth cohorts. The cumulative incidence of varicella was compared between vaccinated and unvaccinated children among the consecutive 4-year birth cohorts.</p><p><b>RESULTS</b>The rate of varicella vaccine coverage, vaccine cumulative incidence among the cohorts was 96.74% (55 317/57 180) and 0.56% (321/57 180). The breakthrough varicella infection for 4-year birth cohorts was 0.44% (244/55 317), and for each birth cohort was 0.95% (142/14 928), 0.44% (61/13 855), 0.22% (29/13 433) and 0.09% (12/13 101), respectively. It was on the rise from 2008 to 2013 and the 2007 birth cohort of it increased fastest from 0.04% (6/14 928) in 2007 to 0.32% (48/14 834) in 2013. The vaccine cumulative incidence of these who vaccinated 1-dose varicella (the breakthrough varicella infection) was lower than these who were unvaccinated (the incidence: 6.25% (37/592), 3.52% (15/426), 3.69% (17/461) and 2.08% (8/384)) by each birth cohort (χ²= 130.27, P < 0.001 for 2007 birth cohort; χ²= 74.11, P < 0.001 for 2008 birth cohort; χ²= 162.80, P < 0.001 for 2009 birth cohort; χ²= 100.01, P < 0.001 for 2010 birth cohort). The vaccine effectiveness for 4-year birth cohorts was 89.33% (95% CI: 86.7%-92.1%) and for each birth corhort was 84.78% (95% CI: 77.94%-89.50%), 86.82% (95% CI: 77.82%-92.95%), 93.99% (95% CI: 89.27%-96.81%) and 95.60% (95% CI: 89.18%-98.21%), respectively. The effectiveness of each birth cohort declinedgradually from 2008 to 2013 and the 2009 birth cohort of it decreased fastest from 98.86% in 2010 to 66.83% in 2013.</p><p><b>CONCLUSIONS</b>The 1-dose varicella vaccine effectiveness was good, but breakthrough varicella infection rate was on the rise with time and the VE declined gradually from 2008 to 2013.</p>
Subject(s)
Child , Humans , Chickenpox , Chickenpox Vaccine , China , Incidence , Vaccination , Vaccine PotencyABSTRACT
In this study ,we analyzed the genetic characterizations and propagation paths of measles viruses prevalent in Ningbo ,China from 2004 to 2013 .Measles viruses were isolated from throat swab specimens from 2004 to 2013 ,and 450 bp fragments of C terminus of nucleoprotein (N) gene were amplified by RT-PCR .Sequence analysis was conducted of all 31 virus strains ,and then compared with other measles virus strains published in GenBank .Results showed that all the 31 measles virus isolates belonged to genotype H1 ,6 strains (one strains in 2004 and 5 ones in 2005) belonged to H1b subtype ,and others be-longed to H1a subtype .Compared the 31 strains to the China 93-4 and China 94-7 ,the homology of 450 bp fragments of C ter-minus of nucleoprotein (N) gene were 97 .1%-100% and 96 .7%-100% ,respectively .The homology of 450 bp fragments of nu-cleotide and nucleotide (amino acids) compared with S191 were 81 .9%-92 .4% and 87 .2%-90 .6% ,respectively .It’s suggested that genotype H1 measles virus circulated in Ningbo from 2004 to 2013 ,and H1a was the predominant epidemic strain ,and H1b strain was existed as well .There are five different transmission chains of H1a subtype caused measles co-circulations in Ning-bo .