Background
SARS-COV-2
Epidemiologic indices used to describe SARS-COV-2
Methods
Study | Location | Study date | Method | Estimated R0 | Other findings |
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Ke et al. | United States and eight European countries | March 2020 | SEIR type | Between 3.5 and 6.4, with the highest amounts of 5.9 (CI 4.7–7.5) and 6.4 (5.2–8.0) for the US and Spain, respectively | Growth rate: between 0.19–0.29/day doubling time: between 2.4 and 3.7 days |
Liu et al. | Based on 12 studies located in China | January 2020 to February 2020 | PubMed, bioRxiv and Google Scholar were accessed | R0 was estimated to be between 1.4 and 6.49 (mean = 3.28, median = 2.79, and interquartile range (IQR) = 1.16) | |
Zhao et al. | China | January 2020 | A method based on the statistical exponential model, adopting SI from SARS and MERS | Between 2.24 (95% CI 1.96–2.55) to 5.71 (95% CI 4.24–7.54) | |
Islam et al. | Bangladesh | March 2021 to July 2021 | Four different methods based on the reported confirmed cases by the government. Including SB, TD, ML, and EG | EG model: 1.173 (95% CI 1.172–1.174) ML model: 1.09 (95% CI 1.08–1.10) SB model: 1.24 (95% CI 1.18–1.29) TD model: 1.07 (95% CI 1.02–1.13) | CFR: 1.32% overall recovery rate: 56.85% |
Study | Location | Study date | Method | Estimated R0 | Other findings |
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Curran et al. | UK | August, 2020 to December, 2020 | Rapid scoping review approach | Transmissibility: 52% (95% CI 46, 58) higher than the other variants Growth rate: 71% (95% CI 65–75%) higher than the other variants | |
Grabowski et al. | UK | October, 2020 to December, 2020 | Based on GISAID data available and Genome Sequence Analysis | Replicative advantage of B.1.1.7 over 20A.EU1: 1.83–2.18 (95% CI 1.71–2.40) Replicative advantage of B.1.1.7 over other strains: 2.03–2.47 (95% CI1.89–2.77) | |
Hunter et al. | UK | October, 2020 to December, 2020 | R for preceding days was obtained by summing all reports of new COVID infections for each day and the previous six days. This was then compared with the sum of new cases over the previous 7-day period | Rt value for B.1.1.7: 1.3, 1.3 and 1.1 Rt value for other strains: 0.92, 0.91 and 0.97 In England, London and South East regions | |
Davies et al. | UK | March, 2020 to December, 2020 | Using a time-varying multinomial spline model | Increased growth rate of + 0.104 day–1 [95% CI 0.100 to 0.108] relative to the previous variant 77% (95% CI 73 to 81%) higher R value | |
Washington et al. | US | December 2020 to January 2021 | SARS-CoV-2 sequencing and Phylogenetic analyses | 35–46% increased transmissibility | |
Sheikhi et al. | Iran | April, 2021 to April, 2021 | EGR, ML, SB, and SIR models | R0: 2.26–11.38 using statistical models 12.13 by time-dependent SIR model (in the time interval with exponential growth) |
Study | Location | Study date | Method | Estimated R0 | Other findings |
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Grabowski et al. | South Africa | October, 2020 to December, 2020 | Based on GISAID data available and Genome Sequence Analysis | Rt: 1.55 (95% CI 1.43–1.69) The relative advantage over other South Africa strains: 1.58 (95% CI 1.45–1.72) |
Study | Location | Study date | Method | Estimated R0 | Other findings |
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Naveca et al. | Amazonas, Brazil | November, 2020 to January, 2021 | Using real-time RT-PCR Ct value as a proxy of viral load | Ct of P.1-positive patients = 19.8 Ct of P.1 negative patients = 23.8 | |
Faria et al. | Amazonas, Brazil | November, 2020 to December, 2020 | Dynamic modeling which integrates genomic information and mortality data | Ct lowered by 1.43 (using E genes) and 1.91 (using N genes) |
Study | Location | Study date | Method | Estimated R0 | Other findings |
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Li et al. | Guangdong, China | May, 2021 to June, 2021 | Calculating viral loads in the oropharyngeal swabs of quarantined individuals by days between exposure and the time of RT-PCR test | Viral loads: 1260-fold higher in delta variant infected patients in comparison to those of the wild-type strain | |
Liu et al. | Review study | Mean R value of delta variant = 5.08 (between 3.2 and 8) Mean R0 of ancestral variant = 2.79 | |||
Tian et al. | Review study | R value of delta variant = 4.04–5.0 R0 of wild-type variants = 2.2–3.77 | GT of the delta variant = 2.9 GT of the wild-type variants = 5.7 |
Study | Location | Study date | Method | Estimated R0 | Other findings |
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Khan et al. | South Africa | November 2021 to January 2022 | Using a mathematical model using the Omicron feature and the accurate data of infected cases | R value = 2.1107 | |
Nishiura et al. | Gauteng province, South Africa | end of November 2021 | Using the data from GISAID, the effective reproduction number of the Omicron variant (Rt) was calculated by assuming that the Rt of omicron is given by multiplying a constant factor k by that of the Delta variant | Rt of the omicron variant: 4.2 times (95% CI 2.1, 9.1) higher than the Rt of the delta variant | |
Jalali et al. | Norway | December 2021 to January 2022 | Use contact tracing data collected by Norwegian municipalities to estimate and compare household | SAR for Omicron variant: 51% (95% CI 48–54) SAR for delta variant: 36% (95% CI 33–40) RR = 1.41 (95% CI 1.27–1.56) VE for Omicron variant = 45% (CI 95 26–57) VE for delta variant = 65% (CI 95 42–80) | |
South Africa | Up to 25 April 2022 | The multinomial logistic regression model | Growth advantages for BA.4 over BA.2 = 0.08 (95% CI 0.07–0.09) Growth advantages for BA.5 over BA.2 = 0.12 (95% CI 0.09–0.15) |