彰化縣新冠疫苗接種現況與效益相關因子探討

Abstract

背景: 2019年底，由中國武漢市引發之COVID-19大流行席捲全球，已造成逾6.7億人感染及680萬人死亡，距今流行已超過三年，因空氣傳播為病毒主要傳播途徑，流行初期為阻斷傳染，多以社交距離、口罩及勤洗手等非醫療介入措施作為防疫措施，而2021年疫苗問世後，開始以接種疫苗為主要的防疫手段。然而隨著變種病毒不斷變異，各國受到Omicron變種病毒肆虐，流行從BA.1/BA.2、BA.4/BA.5、BA.2.75走到XBB.1.5。然而疫苗效益是否有效預防感染及後續中重症也成為後疫情時代重要議題。 目的: 本研究目的欲評估彰化縣疫苗施打對於預防Omicron變種病毒感染、中/重症及死亡效益。 方法: 本研究探討對象為「設籍彰化縣」人口，並自衛生福利部疾病管制署全國預防接種資訊管理系統(簡稱: NIIS系統)獲取個人疫苗接種資料，並結合彰化縣整合式篩檢資料庫，得到參加篩檢民眾資料人口學變項及疾病史等變項，分析各年齡層疫苗接種涵蓋情形，並追蹤其後續新冠肺炎感染、中重症及死亡狀態。此研究為觀察性世代追蹤研究，藉由疫苗施打與否狀態評估此族群新冠肺炎感染、中重症及死亡效益。統計方法使用羅吉斯回歸及時間相依寇斯模型進行統計分析，計算相關因子對於新冠肺炎風險程度及疫苗施打保護效益。 結果: 根據疫苗涵蓋率統計，全彰化縣疫苗未接種及僅接種一劑為13.93%、兩劑為86.07%、追加劑為74.42%，整體而言女性施打率均高於男性，0歲至5歲之幼兒、75歲以上疫苗涵蓋率相較於其他年齡層施打率低。而施打追加劑疫苗相較於未施打追加劑預防感染效益經由時間相依寇斯模型後顯示效益約為12% (Hazard Ratio: 0.883, 95% CI: 0.878-0.889)。此外，施打追加劑疫苗預防中重症(包含入ICU或到院死亡後確診)效益相較於未完整接種疫苗者相比，預防中/重症及後續死亡風險70% (Odds Ratio: 0.30, 95% CI:0.24-0.38。 討論與結論: 本研究初步探討COVID-19疫苗接種之效果，顯示疫苗接種可有效降低部分感染以及降低COVID-19發生中重症風險，可作為公共衛生對於有效遏止COVID-19造成死亡介入措施，然而接種疫苗效益可能隨時間下降，仍需後續研究深入探討。

Background: The COVID-19 pandemic, which began in late 2019 in Wuhan, China, has swept across the globe and has resulted in over 670 million infections and 6.8 million deaths. The pandemic has now lasted over three years, and as airborne transmission is the main route of transmission, early prevention measures focused on non-medical interventions such as social distancing, mask-wearing, and hand hygiene. After the introduction of vaccines in 2021, vaccination became the primary way of preventing the disease. However, as the virus continues to mutate, countries around the world have been hit hard by the Omicron variant, which has progressed from BA.1/BA.2 to BA.4/BA.5, BA.2.75, and XBB.1.5. The effectiveness of the vaccine in preventing infections and subsequent severe or critical illness has become a significant issue in the post-pandemic era. Aims: The objective of this study is to evaluate the effectiveness of vaccination in preventing Omicron variant infection, severe or critical illness, and death in Changhua County. Methods: The study population consists of individuals residing in Changhua County, and personal vaccination data was obtained from the National Immunization Information System (NIIS). The study utilized data collected from the Changhua Community-based Integrated Screening program Database, which includes demographic characteristics and medical history. The vaccination coverage rate of each age group was analyzed, and the subsequent occurrence of COVID-19 infection, severe or critical illness, and death were tracked. This study employed an observational cohort study design, and vaccine status was used to evaluate the effectiveness of vaccination in preventing COVID-19 infection, severe or critical illness, and death. Logistic regression and time-dependent Cox models were used for statistical analysis to calculate the protection provided by vaccination and the associated risk factors. Results: According to the statistics on vaccine coverage, the percentage of people in Changhua County who have not received the vaccine or have only received one dose is 13.93%, while those who have received two doses are 86.07%, and those who have received booster doses are 74.42%. Overall, the vaccination rate for females is higher than that of males, and the vaccine coverage rate for children aged 0-5 and those aged 75 and above is lower than that of other age groups. In addition, the effectiveness of receiving a booster vaccine compared to not receiving one, as measured by a time-dependent Cox model, is about 12% (Hazard Ratio: 0.883, 95% CI: 0.878-0.889). Furthermore, the efficacy of receiving a booster vaccine in preventing moderate-to-severe disease (including ICU admission or death after hospital admission) is 70% lower than that of those who have not completed their vaccination (Odds Ratio: 0.30, 95% CI: 0.24-0.38) Conclusion: This study provides preliminary evidence that COVID-19 vaccination can effectively reduce some infections and lower the risk of severe illness caused by COVID-19. This can serve as a public health intervention to effectively prevent COVID-19-related deaths. However, the effectiveness of vaccination may decrease over time, and further research is needed to explore this issue.