台灣某社區兒童COVID-19感染：特徵、流行病學與中重症風險分析

Abstract

研究目的 2022年，SARS-CoV-2 Omicron變異株在台灣兒童中引發大規模COVID-19感染高峰。然而，兒童首次感染Omicron變異株的特徵、流行病學，以及中重症的發生情況尚未明確。本研究分析彰化全縣兒童確診資料，以了解兒童首次感染SARS-CoV-2 Omicron變異株的特徵和流行病學，並分析兒童COVID-19中重症發生比例及相關危險因子。 研究方法 研究使用彰化縣COVID-19疫情監測資料，進行回顧性分析研究。資料收集自2022年4月起至2023年3月止，期間內所有十八歲以下確診SARS-CoV-2兒童。研究分析確診兒童的人口統計學特徵、感染流行病學數據和疫苗接種狀況，並應用多變量羅吉斯迴歸及貝氏羅吉斯迴歸，分析發生COVID-19中重症與否之相關風險因子。 研究結果 研究期間，彰化縣共有85,702例兒童COVID-19確診案例，其中男性佔52.9%，年齡中位數為10歲（四分位數間距6-14歲）。不同年齡層兒童的感染率在Omicron變異株的不同亞型感染高峰中，具顯著差異：第一波BA.2亞型感染高峰以六個月至四歲的幼兒感染率最高，第二波BA.5亞型感染高峰以十二至十七歲的青少年感染率最高，而第三波BA.2.75亞型感染高峰則各年齡層的累積確診率相對平均。在所有兒童確診案例中，中重症共38例（0.044%），其中包括7例死亡案例。多變量羅吉斯迴歸分析結果顯示，年齡層和疫苗接種劑數為中重症發生的顯著影響因子。年齡較小的兒童更易發展為COVID-19中重症，尤其是零至六個月嬰兒，與十二歲以下其他年齡層相比，得到中重症的概率較高。疫苗接種率以十二至十七歲的青少年最高（83.4%），六個月至四歲幼兒接種率最低（10.0%）。而完成兩劑疫苗接種顯著降低了發展為中重度 COVID-19 的概率，多變量羅吉斯迴歸（調整勝算比為0.14，95%信賴區間0.06-0.35，P值 < 0.001）及貝氏羅吉斯迴歸分析（勝算比為0.05，95%信賴區間0.04-0.06）結果一致，均顯示接種疫苗有顯著保護作用。 結論 在國內Omicron 流行高峰期間，相較成人病患，兒童族群中SARS-CoV-2感染顯著，相較成人病患，兒童的累積確診率更高。愈年幼的兒童愈少完整接種SARS-CoV-2疫苗，而不完全的疫苗接種與發生COVID-19中重症顯著相關。本研究提供一般社區兒童大規模SARS-CoV-2感染之流行病學全貌，提示相關衛生主管單位，應加強重視並普及幼兒族群疫苗接種，確保幼兒得到足夠保護力，避免COVID-19中重症發生。

Objective Native infection of SARS-CoV-2 Omicron variant caused large-scale domestic COVID-19 peaks among Taiwan pediatric population in 2022. However, the characteristics, epidemiology, and incidence of severe COVID-19 of children infected with the Omicron variant for the first time remain unclear. This study analyzes the confirmed cases of children in Changhua County to understand the characteristics and epidemiology of the native Omicron infections in children and to determine the proportion and risk factors associated with severe COVID-19. Method This retrospective study used COVID-19 surveillance data from Changhua County. Data were collected from April 2022 to March 2023, including all confirmed SARS-CoV-2 cases in children under 18. The study analyzed demographic characteristics, epidemiological data, and vaccination status of the confirmed cases. Multivariate logistic regression and Bayesian logistic regression were used to identify risk factors associated with severe COVID-19. Result During the study period, there were 85,702 confirmed pediatric COVID-19 cases in Changhua County, with male accounting for 52.9% and a median age of 10 years (IQR 6-14 years). The cumulative incidence varied significantly among different age groups during the peaks of different Omicron subvariants: during the first BA.2 subvariant peak, the highest infection rate was among infants aged 6 months to 4 years; highest incidence among adolescents aged 12 to 17 years was found in the second BA.5 subvariant peak; and during the third BA.2.75 subvariant peak, the cumulative incidences were similar between all age groups. There were 38 severe cases (0.044%) among all confirmed pediatric cases, including 7 deaths. Multivariate logistic regression analysis indicated that age group and the number of vaccine doses were significant factors influencing the development of severe COVID-19. Younger children were more likely to develop severe COVID-19, especially infants aged 0 to 6 months, who had a higher probability of severe COVID-19 compared to other age groups under 12. Vaccination rates were highest among adolescents aged 12 to 17 years (83.4%) and lowest among infants aged 6 months to 4 years (10.0%). Completing two doses of vaccine significantly reduced the likelihood of developing severe COVID-19. The results of multivariate logistic regression (OR: 0.14, 95% CI: 0.06-0.35, P < 0.001) and Bayesian logistic regression (OR: 0.05, 95% CI: 0.04-0.06) consistently demonstrated a significant protective effect of vaccination. Conclusion SARS-CoV-2 infections were notably prevalent among the pediatric population during domestic Omicron peaks. Younger children tended to receive fewer vaccine doses, and incomplete vaccination was significantly associated with the occurrence of severe COVID-19. This study provides an epidemiological overview of large-scale SARS-CoV-2 infections among children in the general community, highlighting the need for health authorities to focus on and promote vaccination among young children to ensure adequate protection and prevent severe COVID-19 cases.