During an outbreak, the number of cases rises from 10 to 70 over a period of 7 days, assuming exponential growth. (a) Calculate the daily exponential growth rate $r$ (day$^{-1}$). (b) Using a generation time of 5 days, estimate the basic reproduction number $R_{0}=e^{r\,g}$. (c) If public health measures reduce contacts by 40 %, what is the effective reproduction number $R_{e}$ and will the outbreak continue to grow (i.e., is $R_{e}1$)?

Question

During an outbreak, the number of cases rises from 10 to 70 over a period of 7 days, assuming exponential growth. (a) Calculate the daily exponential growth rate $r$ (day$^{-1}$). (b) Using a generation time of 5 days, estimate the basic reproduction number $R_{0}=e^{r\,g}$. (c) If public health measures reduce contacts by 40 %, what is the effective reproduction number $R_{e}$ and will the outbreak continue to grow (i.e., is $R_{e}>1$)?

Accepted Answer

r = 0.278 day⁻¹; R₀ ≈ 4.0; Rₑ ≈ 2.4 (outbreak continues)

Igcse Model Questions Vol1 2024 Biology Question 30

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