Percorrer por autor "Loyens, Dinis B."
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- Impact of non-pharmacological interventions on the first wave of COVID-19 in Portugal 2020Publication . Loyens, Dinis B.; Caetano, Constantino; Matias-Dias, CarlosIntroduction: The COVID-19 pandemic caused over 7 million global deaths. Without vaccines during the first wave, governments implemented nonpharmacological interventions (NPIs) such as lockdowns, school closures, and travel restrictions. This study quantifies the impact of NPIs on COVID-19 transmission in Portugal between 24th February and 1st May. Methods: A compartmental SEIR (Susceptible, Exposed, Infectious, Removed) model was employed to simulate the first COVID-19 wave in Portugal, using a Bayesian approach and symptom-onset incidence data. The effect of the lockdown, which began on March 22, 2020, on the effective reproductive number, R t was measured. A counterfactual scenario was created to ascertain the number of cases prevented by the NPIs during the first 15 days after the implementation of NPI. Results: The lockdown reduced overall transmission by 68·6 % (95%Credible Interval (95%CrI): 59·2 %; 77·5 %), almost immediately. This corresponds to a reduction in the effective reproductive number from 2·56 (95%CrI: 2·08; 3·40) to 0·80 (95%CrI: 0·76; 0·84). The counterfactual scenario estimated that the lockdown prevented 118052 (95%CrI: 99464; 145605) cases between 24th February and 6th April. Discussion: The lockdown significantly reduced COVID-19 transmission in Portugal, bringing Rt below 1, meaning each person infected fewer than one individual. While costly, lockdowns effectively control disease spread in the absence of vaccines. Conclusion: Our findings suggest NPIs curbed epidemic transmission, reducing Rt below 1 and easing hospital loads and deaths. This research will help inform future pandemic decision-making and infectious disease modeling worldwide.
- Viral genetics and transmission dynamics in the second wave of mpox outbreak in Portugal and forecasting public health scenariosPublication . Cordeiro, Rita; Caetano, Constantino P.; Sobral, Daniel; Ferreira, Rita; Coelho, Luís; Pelerito, Ana; de Carvalho, Isabel Lopes; Namorado, Sónia; Loyens, Dinis B.; Mexia, Ricardo; Fernandes, Cândida; Neves, José Miguel; João, Ana Luísa; Rocha, Miguel; Duque, Luís Miguel; Correia, Inês; Baptista, Teresa; Brazão, Cláudia; Sousa, Diogo; Filipe, Paulo; Alpalhão, Miguel; Maltez, Fernando; Póvoas, Diana; Pinto, Raquel; Caria, João; Patrocínio de Jesus, Rita; Pacheco, Patrícia; Peruzzu, Francesca; Méndez, Josefina; Ferreira, Luís; Mansinho, Kamal; Alves, João Vaz; Vasconcelos, Joana; Domingos, João; Casanova, Sara; Duarte, Frederico; Gonçalves, Maria João; Salvador, Mafalda Brito; Guimarães, Mafalda Andresen; Martins, Sueila; Oliveira, Marvin Silva; Santos, Daniela; Vieira, Luís; Núncio, Maria Sofia; Borges, Vítor; Gomes, João PauloIn 2023, a second wave of the global mpox epidemic, which is mainly affecting men who have sex with men (MSM), was observed in some countries. Herein, we benefited from a large viral sequence sampling (76/121; 63%) and vast epidemiological data to characterise the re-emergence and circulation of the (MPXV) in Portugal during 2023. We also modelled transmission and forecasted public health scenarios through a compartmental susceptible-exposed-infectious-recovered (SEIR) model. Our results suggest that the 2023 mpox wave in Portugal resulted from limited introduction(s) of MPXV belonging to C.1.1 sublineage, hypothetically from Asia, followed by sustained viral transmission and potential exportation to other countries. We estimated that the contribution of the MSM high sexual activity group to mpox transmission was 120 (95% CrI: 30-3553) times higher than that of the low sexual activity group. However, among the high sexual activity group, vaccinated individuals likely contributed approximately eight times less [0.123 (95% CrI: 0.068-0.208)] than the unvaccinated ones. Vaccination was also linked to potential reduced disease severity, with a Mpox Severity Score of 6.0 in the vaccinated group compared to 7.0 in unvaccinated individuals. Scenario analysis indicated that transmission is highly sensitive to sexual behaviour, projecting that a slight increase in the MSM sub-population with high sexual activity can trigger new mpox waves. This study strongly supports that continued vaccination, targeted awareness among risk groups and routine genomic epidemiology is needed to anticipate and respond to novel MPXV threats (e.g. global dissemination of clade I viruses).