Publicação
Transmission dynamics and the impact of non-pharmaceutical interventions in the COVID-19 epidemic in Portugal : a modelling study
| Resumo: | Background: In response to the COVID-19 epidemic, Portugal adopted non-pharmaceutical interventions (NPIs), including closing schools, contact tracing, and other social distancing measures, to contain the spread of SARS-CoV-2. Projecting the size of the epidemic under different NPIs and investigating their effectiveness to reduce spread have been essential to support governments’ response. This dissertation aims to develop a mathematical model to simulate the spread of SARS-CoV-2 in Portugal between March 2020 and February 2021 and explore the impact of different NPIs in controlling the epidemic. Besides an unmitigated scenario, the NPIs explored comprise different physical distancing interventions and additional efforts in tracing and isolating infected contacts. Methods: We present an age-structured compartment model (an extension of the SEIR model) for SARS CoV-2, accounting for the different stages of infection and disease, realistic distributions of infectious periods, and the Portuguese population’s heterogeneities, including age structure and social contact patterns. For each scenario, we estimated the burden of morbidity and mortality, the demand on healthcare facilities, and the fraction of infections averted. Results: Our results suggest that the early control measures implemented on 18th March 2020 flattened the epidemic curve and avoided overwhelming the National Health System. The different NPIs could reduce the number of infections, deaths and pressure on the healthcare systems. Importantly, the third wave could have been avoided, as demonstrated by maintaining virtual learning for the 2020/2021 academic year or maintaining the 2020 Christmas under extreme restrictions, although these measures may have other social consequences. The impact of additional tracing efforts shows to be dependent on the number of active infectious cases, with periods of higher transmission implying more contact tracing effort and human resources. Conclusion: The success of NPIs to curb SARS-CoV-2 transmission relies on a rapid and effective response which is crucial to determining the COVID-19 epidemic growth. |
|---|---|
| Autores principais: | Luís, Márcia Maria Galrão |
| Assunto: | COVID-19 Epidemics Mathematical modelling Non-pharmaceutical interventions Contact tracing Portugal Epidemiology Teses de mestrado - 2022 |
| Ano: | 2022 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | Background: In response to the COVID-19 epidemic, Portugal adopted non-pharmaceutical interventions (NPIs), including closing schools, contact tracing, and other social distancing measures, to contain the spread of SARS-CoV-2. Projecting the size of the epidemic under different NPIs and investigating their effectiveness to reduce spread have been essential to support governments’ response. This dissertation aims to develop a mathematical model to simulate the spread of SARS-CoV-2 in Portugal between March 2020 and February 2021 and explore the impact of different NPIs in controlling the epidemic. Besides an unmitigated scenario, the NPIs explored comprise different physical distancing interventions and additional efforts in tracing and isolating infected contacts. Methods: We present an age-structured compartment model (an extension of the SEIR model) for SARS CoV-2, accounting for the different stages of infection and disease, realistic distributions of infectious periods, and the Portuguese population’s heterogeneities, including age structure and social contact patterns. For each scenario, we estimated the burden of morbidity and mortality, the demand on healthcare facilities, and the fraction of infections averted. Results: Our results suggest that the early control measures implemented on 18th March 2020 flattened the epidemic curve and avoided overwhelming the National Health System. The different NPIs could reduce the number of infections, deaths and pressure on the healthcare systems. Importantly, the third wave could have been avoided, as demonstrated by maintaining virtual learning for the 2020/2021 academic year or maintaining the 2020 Christmas under extreme restrictions, although these measures may have other social consequences. The impact of additional tracing efforts shows to be dependent on the number of active infectious cases, with periods of higher transmission implying more contact tracing effort and human resources. Conclusion: The success of NPIs to curb SARS-CoV-2 transmission relies on a rapid and effective response which is crucial to determining the COVID-19 epidemic growth. |
|---|