In the article by K. D. Ricketts, A. Charlett, D. Gelb, C. Lane, J. V. Lee and C. A. Joseph [Reference Ricketts, Charlett, Gelb, Lane, Lee and Joseph1] presented in Epidemiology and Infection, there was an error in the equation on page 1005. The correct equation is published below:
![\eqalign{ \tab{\rm Es} \equals 6{ \cdot}11\ast 10{ \cdot}0\6 ^{\wedge} \lpar 7{ \cdot}5\ast {\rm Tc}\sol \lpar 237{ \cdot}7 \plus {\rm Tc}\rpar \rpar \cr \tab {\rm E} \equals 6{ \cdot}11\ast 10{ \cdot}0^{\wedge}\lpar 7{ \cdot}5\ast {\rm Tdc}\sol \lpar 237{ \cdot}7 \plus {\rm Tdc}\rpar \rpar \cr}](https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20160921000648771-0136:S095026881100135X:S095026881100135X_eqnU1.gif?pub-status=live)