Gascó-Laborda Juan Carlos, Gil-Fortuño Maria, Tirado-Balaguer Maria Dolores, Meseguer-Ferrer Noemi, Sabalza-Baztán Oihana, Pérez-Olaso Óscar, Gómez-Alfaro Iris, Poujois-Gisbert Sandrine, Hernández-Pérez Noelia, Lluch-Bacas Lledó, Rusen Viorica, Arnedo-Pena Alberto, Bellido-Blasco Juan Bautista
Epidemiology Division, Public Health Center, 12003 Castelló de la Plana, Spain.
Microbiology Laboratory, Universitary Hospital de la Plana, 12540 Vila-Real, Spain.
Epidemiologia (Basel). 2024 Oct 16;5(4):658-668. doi: 10.3390/epidemiologia5040046.
Backgound/Objectives: Cycle threshold (Ct) values of SARS-CoV-2 real-time reverse transcriptase-polymerase chain reaction (RT-PCR) tests are associated with infectivity and viral load, and they could be an aid in forecasting the evolution of SARS-CoV-2 outbreaks. The objective was to know the Ct values related to the incidence and reinfection of SARS-CoV-2 in successive outbreaks, which took place in nursing homes in Castellon (Spain) during 2020-2022, and to test its usefulness as an instrument of epidemic surveillance in nursing homes.
a retrospective cohort design with Poisson regression and multinomial logistic regression were used.
We studied four nursing home SARS-CoV-2 outbreaks, and the average infection rate, reinfection rate, and case fatality were 72.7%, 19.9%, and 5.5%, respectively; 98.9% of residents were vaccinated with three doses of a mRNA SARS-CoV-2 vaccine. Ct values for first infections and reinfections were 27.1 ± 6.6 and 31.9 ± 5.4 ( = 0.000). Considering Ct values ≥ 30 versus <30, residents with reinfections had Ct values higher than residents with a first infection, an adjusted relative risk of 1.66 (95% Confidence interval 1.10-2.51). A sensitivity analysis confirmed these results.
Reinfection and SARS-CoV-2 vaccination (hybrid immunity) could protect against severe disease better than vaccination alone. High Ct values suggest lower transmission and severity. Its value can be useful for surveillance and forecasting future SARS-CoV-2 epidemics.
背景/目的：严重急性呼吸综合征冠状病毒2（SARS-CoV-2）实时逆转录聚合酶链反应（RT-PCR）检测的循环阈值（Ct）值与传染性和病毒载量相关，并且它们可能有助于预测SARS-CoV-2疫情的演变。目的是了解与2020年至2022年期间在西班牙卡斯特利翁的养老院发生的连续疫情中SARS-CoV-2的发病率和再感染相关的Ct值，并测试其作为养老院疫情监测工具的有用性。
采用泊松回归和多项逻辑回归的回顾性队列设计。
我们研究了四起养老院SARS-CoV-2疫情，平均感染率、再感染率和病死率分别为72.7%、19.9%和5.5%；98.9%的居民接种了三剂mRNA SARS-CoV-2疫苗。首次感染和再感染的Ct值分别为27.1±6.6和31.9±5.4（ = 0.000）。考虑Ct值≥30与<30，再感染居民的Ct值高于首次感染居民，调整后的相对风险为1.66（95%置信区间1.10 - 2.51）。敏感性分析证实了这些结果。
再感染和SARS-CoV-2疫苗接种（混合免疫）比单独接种疫苗能更好地预防重症疾病。高Ct值表明传播和严重程度较低。其价值可用于监测和预测未来的SARS-CoV-2疫情。
