Department of Surgery, Tulane University, School of Medicine, New Orleans, Louisiana.
Genetics Unit, Department of Histology and Cell Biology, Faculty of Medicine, Suez Canal University, Ismailia, Egypt.
Ann Surg. 2021 Jan 1;273(1):28-33. doi: 10.1097/SLA.0000000000004590.
To quantify the time-varying reproductive rates for SARS-CoV-2 and its implication in Louisiana.
Basic reproductive number (R0) and effective reproductive number (Re or Rt) are 2 measures of the ability of an infectious agent to spread in the environment. They differ in that R0 assumes zero immunity in the population, while Re or Rt accounts for change over time. Reproductive number modeling is influenced by several factors, including serial interval, the time between the onset of symptoms in an infector, and a secondary case. Quantification of the ability of a pathogen to spread is essential in guiding policy.
Here, we construct epidemic curves and calculate daily Rt values for the state of Louisiana and each of its 9 regions.
Our results demonstrated variation over both time and geography in calculated R0 and Rt values. Generally, as time has progressed, predicted R0 and Rt values have decreased. In Louisiana, mean Rt was calculated at 3.07 in March and 0.82 by May. A reproductive number less than one is important as it indicates infectious spread will decline with time. The most recent finding of mean Rt = 0.82 is important. It stands in stark contrast to the situation in April when New Orleans, Louisiana, had the highest per capita coronavirus mortality rate in the United States - twice that of New York City and 4 times the rate in Seattle.
As locations around the world begin to lift restrictions, monitoring of infectious spread will be essential.
量化 SARS-CoV-2 的时变繁殖率及其在路易斯安那州的意义。
基本繁殖数（R0）和有效繁殖数（Re 或 Rt）是衡量传染性病原体在环境中传播能力的两个指标。它们的区别在于，R0 假设人群中没有免疫力，而 Re 或 Rt 则考虑了随时间的变化。繁殖数模型受到几个因素的影响，包括序列间隔，感染者症状发作与二次感染病例之间的时间。量化病原体传播的能力对于指导政策至关重要。
在这里，我们构建了路易斯安那州及其 9 个地区的疫情曲线，并计算了每日 Rt 值。
我们的结果表明，计算出的 R0 和 Rt 值在时间和地理上都存在差异。一般来说，随着时间的推移，预测的 R0 和 Rt 值呈下降趋势。在路易斯安那州，3 月的平均 Rt 值为 3.07，5 月为 0.82。繁殖数小于 1 很重要，因为这表明随着时间的推移，传染性传播将减少。最近发现的平均 Rt=0.82 很重要。这与路易斯安那州新奥尔良市的情况形成鲜明对比，当时该市的人均冠状病毒死亡率是美国最高的，是纽约市的两倍，是西雅图的四倍。
随着世界各地的地方开始放宽限制，对传染性传播的监测将至关重要。
