COVID-19 reproduction number higher than WHO estimates


  • Heather Mason
  • Univadis Medical News
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Researchers at Umea University in Sweden say the reproduction number (R0) of COVID-19 is greater than previously thought. The team calculated that the average R0 for COVID-19 to be 3.28, exceeding the World Health Organization (WHO) estimates of 1.4 to 2.5

Results from 12 studies estimated the range of R0 from 1.4 to 6.49. Differences in calculation methods (stochastic, mathematical or statistical methods) lead to this wide range of values. Later R0 estimations are likely to be more reliable due to the increase in case data and they include the effect of awareness and intervention.

This review found that the average R0  to be 3.28 (median 2.79), exceeding WHO estimates of 1.4 to 2.5. WHO point estimates are consistently lower than all published estimates. R0 estimates for SARS have been reported to range between 2-5, within the range of the mean for COVID-19 in this review. However COVID-19 is already more widespread than SARS, indicating that it may be more transmissible.

As more data is accumulated estimation error is likely to decrease. Therefore, the R0 for COVID-19 is expected to be 2-3, broadly consistent with the WHO estimate.

As of February 17, global figures are 71,429 confirmed cases and 1,775 deaths.