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Table 6 Summary of studies on the reproduction number of the omicron variant

From: The reproduction rate of severe acute respiratory syndrome coronavirus 2 different variants recently circulated in human: a narrative review

Study

Location

Study date

Method

Estimated R0

Other findings

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)

  1. SAR, secondary attack rate; RR, relative ratio; VE, vaccine efficacy