Association Of Meteorological Factors And Air Pollutants With The Incidence Of Adult Varicella

Objective: Varicella is a childhood infectious disease.However,varicella in adults is often accompanied by serious complications,so it is particularly necessary to pay attention to adult varicella.The purpose of this study is to:(1)describe the epidemic characteristics of adult varicella in Qingdao;(2)explore the correlation between meteorological factors and adult varicella;(3)assess the relationship between air pollutants and adult varicella.The results could provide the evidence for reasonably setting the scientific strategy of adult varicella.Methods: The daily meteorological factor data from 2008 to 2019,the daily air pollution data from 2014 to 2019,and the daily incidence of adult varicella from 2008 to 2019 were obtained to establish a time-series database.The above data were descriptively analyzed.Spearman correlation coefficient matrix was used to assess the correlation among daily meteorological factors,air pollutants,and the cases of adult varicella.According to the results of the correlation coefficient matrix,we selected daily average temperature,daily average relative humidity,daily average wind speed,daily cumulative precipitation,daily average sunshine duration,daily inhalable particulate matter(PM10)concentration,daily fine particulate matter(PM2.5)concentration,daily nitrogen dioxide(NO2)concentration,daily sulfur dioxide(SO2)concentration,and daily maximum 8-hour moving average concentration of ozone(O3-8h)into our subsequent analyses.Firstly,the combination of quasi-Poisson generalized additive model(GAM)and distributed lag non-linear model(DLNM)was used to assess the relationships between meteorological factors and daily cases of adult varicella.Taking the levels of each meteorological factor when the risk of varicella is lowest as references,the exposureresponse relationship,lag-response relationship,and response-lag-relationship of each meteorological factor were explored.Secondly,quasi-Poisson DLNM was conducted to assess the relationships between air pollutants and daily cases of adult varicella.The level II of GB3095-2012 was used as the reference.We explored the exposure-lag-response relationships of each air pollutant on the risk of adult varicella.And the effects of exposure to extremely high concentration(at 97.5th percentile)and low concentration(at 2.5th percentile)of air pollutants on varicella were also calculated.The natural cubic spline function(ns)was used to control seasonal and long-term trends,and the degrees of freedom(df)of spline functions were automatically selected according to the minimum Generalized Cross Validation(GCV)score.All analyses were performed in R 3.6.3,and the involved packages were “dlnm”,“mgcv”,and “splines”.We used a two-sided test and p < 0.05 was considered to be statistically significant.Results: 10,296 adult cases were reported in Qingdao from January 1,2008 to December 31,2019.The female/male ratio was 1.044:1(5,580:5,346).The incidence was rising generally during the study period.(1)In overall cumulative temperature-varicella association,compared with 25℃,the largest effect of temperature on varicella within 20 lag days was at 1℃(RR,6.72;95% CI,2.90-15.57),and then RR declined as the temperature increased.In the lag-response relationships at 5 ℃,14.5 ℃,and 21.8 ℃ and the exposure-response relationships at 5,10,and 15 days,the effects of the daily average temperature on varicella cases were statistically significant.(2)In overall cumulative humidity-varicella association,compared with 100%,RR showed a gradually downward trend until the daily average relative humidity was 47%,which RR was 3.68 and 95% CI was 1.67-8.09.After that,the RR was beginning to stabilize.The lag-response relationships at 56%,70%,and 84% were statistically significant,and a similar trend of decreasing first and then increasing was found.In the exposure-response relationships at 5,10,and 15 days,the daily average relative humidity significantly affects the incidence of varicella.(3)A 10 μg/m3 increase of PM2.5 was significantly associated with an increased risk of varicella(lag day: 4,5,and 6).The high PM2.5 concentration(135 μg/m3)was significantly associated with the increased risk of varicella(lag day: 6,7).(4)The negative associations were found for NO2 per 10 μg/m3 increase from lag 15 to 19 day.The negative association was found at high concentration(75 μg/m3)on lag 15 to 20 day;the positive relationship was shown at low concentration(10 μg/m3)on lag 15 to 20 day.Conclusion: Exposure to daily mean temperature,daily mean relative humidity,PM2.5,and NO2 were significantly associated with the risk of varicella among adults.