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Volume 28, Number 7—July 2022
Research

Measuring Basic Reproduction Number to Assess Effects of Nonpharmaceutical Interventions on Nosocomial SARS-CoV-2 Transmission

George ShirreffComments to Author , Jean-Ralph Zahar, Simon Cauchemez, Laura Temime1, Lulla Opatowski1, and EMEA-MESuRS Working Group on the Nosocomial Modelling of SARS-CoV-22
Author affiliations: Institut Pasteur, Université Paris Cité, Paris, France (G. Shirreff, S. Cauchemez, L. Opatowski); Conservatoire National des Arts et Métiers, Paris (G. Shirreff, L. Temime); University of Versailles Saint-Quentin-en-Yvelines, Montigny-le-Bretonneux, France (G. Shirreff, L. Opatowski); Assistance Publique–Hôpitaux de Paris, Bobigny, France (J.-R. Zahar); PACRI Unit, Paris (L. Temime)

Main Article

Table 1

Best estimates and ranges for parameters from 2 models applied to hospital data from a long-term care facility in France to estimate nosocomial transmission rates of SARS-CoV-2*

Parameter Model
1-phase 2-phase
β 0.38 (0.30–0.60) NA
β1 NA 1.28 (0.76–2.40)
β2
 NA
 0.19 (0.10–0.30)
R0† 2.6 (2.0–4.1) NA
R0 before NA 8.72 (5.14–16.32)
R0 after NA 1.33 (0.68–2.04)
R0 combined
 NA
 5.72 (3.62–8.70)
Intervention efficacy‡ NA 0.85 (0.66–0.94)
tinit
 −22 (−39 to −4)
 −4 (−25 to −1)
AIC 657.33 628.85

*The value of Einit was fixed at day 1 and the value of tinflect at day 12. The R0 values were calculated by using equations 4 and 5 (Appendix). AIC, Akaike information criterion; NA, not applicable; R0, basic reproduction number; β, current transmission rate per day; β1, transmission rate per day before inflection date; β2, transmission rate per day after inflection date; Einit, number of initial infections at date tinit; R0, basic reproduction number; tinit, date on which the initial infection occurs. †R0 was calculated before and after inflection date in the 2-phase model. ‡The intervention efficacy was calculated as 1 – β2/β1. Days for tinit are relative to the first positive sample on day 1.

Main Article

1These authors were co-principal investigators.

2Members of the workgroup are listed at the end of this article.

Page created: April 28, 2022
Page updated: June 18, 2022
Page reviewed: June 18, 2022
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