The infection by SARS-CoV-2 appeared for the first time in 2019, and several factors that influenced its spread remain unclear. Although many studies investigated the seasonality of this infection, most of the findings are controversial across time and geographical space, highlighting the need for further research, particularly in Africa, where the low number of cases was surprising. This study aims to investigate the potential seasonality of infection by SARS-CoV-2, considering three main climate zones, namely tropical, arid, and temperate zones. To do so, an extended SEIR model of eight classes, including susceptible (S), vaccinated susceptible (<InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40808_2024_2236_Article_IEq1.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">$S_v$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>S</mi> <mi>v</mi> </msub> </math></EquationSource> </InlineEquation>), exposed (E), pre-symptomatic infectious (<InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40808_2024_2236_Article_IEq2.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="16" /> </InlineMediaObject> <EquationSource Format="TEX">$I_p$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>I</mi> <mi>p</mi> </msub> </math></EquationSource> </InlineEquation>), asymptomatic infectious (<InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40808_2024_2236_Article_IEq3.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="17" /> </InlineMediaObject> <EquationSource Format="TEX">$I_a$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>I</mi> <mi>a</mi> </msub> </math></EquationSource> </InlineEquation>), symptomatic infectious (<InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40808_2024_2236_Article_IEq4.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="16" /> </InlineMediaObject> <EquationSource Format="TEX">$I_s$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>I</mi> <mi>s</mi> </msub> </math></EquationSource> </InlineEquation>), detected infectious (<InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40808_2024_2236_Article_IEq5.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="17" /> </InlineMediaObject> <EquationSource Format="TEX">$I_d$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>I</mi> <mi>d</mi> </msub> </math></EquationSource> </InlineEquation>), and recovered (R), was developed considering 25 African countries. The model accounted for seasonality through the transmission rates using a cosine seasonal forcing. After estimating the seasonality amplitudes of the transmission rates for each country, a Kruskal-Wallis H test was used to check for variation among the climate zones. Then, a sensitivity analysis was carried out to assess the effect of seasonality amplitudes of the transmission rates on the control reproduction number (<InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40808_2024_2236_Article_IEq6.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="21" /> </InlineMediaObject> <EquationSource Format="TEX">$R_c$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>R</mi> <mi>c</mi> </msub> </math></EquationSource> </InlineEquation>) using the Partial Rank Correlation Coefficient. Results showed that the seasonality amplitude of the asymptomatic transmission is one of the main driving factors of the pandemic, and more so in the Temperate zone where the weather is mostly cold. Therefore, in the event of a re-emergence of SARS-CoV-2 in the temperate zone, in addition to isolating and caring for symptomatic individuals, preventing the spread of SARS-CoV-2 from asymptomatic infectious individuals through mass testing can significantly reduce the burden of the pandemic, especially in the cold season. The same measure can be applied in other regions of the continent, particularly during cold and rainy periods.

Assessing the potential seasonality of COVID-19 dynamic in Africa: a mathematical modeling study

期刊论文
发表日期：

2025年2月3日

查看全文

Yvette Montcho,
Koomi Toussaint Amoussouvi,
Mintodê Nicodème Atchadé,
Kolawole Valère Salako,
Mahouton Norbert Hounkonnou,
Martin Wolkewitz,
Romain Glèlè Kakaï

摘要

The infection by SARS-CoV-2 appeared for the first time in 2019, and several factors that influenced its spread remain unclear. Although many studies investigated the seasonality of this infection, most of the findings are controversial across time and geographical space, highlighting the need for further research, particularly in Africa, where the low number of cases was surprising. This study aims to investigate the potential seasonality of infection by SARS-CoV-2, considering three main climate zones, namely tropical, arid, and temperate zones. To do so, an extended SEIR model of eight classes, including susceptible (S), vaccinated susceptible ( $S_v$ $S_{v}$ ), exposed (E), pre-symptomatic infectious ( $I_p$ $I_{p}$ ), asymptomatic infectious ( $I_a$ $I_{a}$ ), symptomatic infectious ( $I_s$ $I_{s}$ ), detected infectious ( $I_d$ $I_{d}$ ), and recovered (R), was developed considering 25 African countries. The model accounted for seasonality through the transmission rates using a cosine seasonal forcing. After estimating the seasonality amplitudes of the transmission rates for each country, a Kruskal-Wallis H test was used to check for variation among the climate zones. Then, a sensitivity analysis was carried out to assess the effect of seasonality amplitudes of the transmission rates on the control reproduction number ( $R_c$ $R_{c}$ ) using the Partial Rank Correlation Coefficient. Results showed that the seasonality amplitude of the asymptomatic transmission is one of the main driving factors of the pandemic, and more so in the Temperate zone where the weather is mostly cold. Therefore, in the event of a re-emergence of SARS-CoV-2 in the temperate zone, in addition to isolating and caring for symptomatic individuals, preventing the spread of SARS-CoV-2 from asymptomatic infectious individuals through mass testing can significantly reduce the burden of the pandemic, especially in the cold season. The same measure can be applied in other regions of the continent, particularly during cold and rainy periods.