LOCUS (LOng Covid-Understanding Symptoms, events and use of services in Portugal): A three-component study protocol.

Approximately 10% of patients experience symptoms of Post COVID-19 Condition (PCC) after a SARS-CoV-2 infection. Akin acute COVID-19, PCC may impact a multitude of organs and systems, such as the cardiovascular, respiratory, musculoskeletal, and neurological systems. The frequency and associated risk factors of PCC are still unclear among both community and hospital settings in individuals with a history of COVID-19. The LOCUS study was designed to clarify the PCC's burden and associated risk factors. LOCUS is a multi-component study that encompasses three complementary building blocks. The "Cardiovascular and respiratory events following COVID-19" component is set to estimate the incidence of cardiovascular and respiratory events after COVID-19 in eight Portuguese hospitals via electronic health records consultation. The "Physical and mental symptoms following COVID-19" component aims to address the community prevalence of self-reported PCC symptoms through a questionnaire-based approach. Finally, the "Treating and living with Post COVID-19 Condition" component will employ semi-structured interviews and focus groups to characterise reported experiences of using or working in healthcare and community services for the treatment of PCC symptoms. This multi-component study represents an innovative approach to exploring the health consequences of PCC. Its results are expected to provide a key contribution to the optimisation of healthcare services design.

COVID-19 surveillance: Large decrease in clinical notifications and epidemiological investigation questionnaires for laboratory-confirmed cases after the 2nd epidemic wave, Portugal March 2020-July 2021.

Introduction: In Portugal, COVID-19 laboratory notifications, clinical notifications (CNs), and epidemiological investigation questionnaires (EI) were electronically submitted by laboratories, clinicians, and public health professionals, respectively, to the Portuguese National Epidemiological Surveillance System (SINAVE), as mandated by law. We described CN and EI completeness in SINAVE to inform pandemic surveillance efforts. Methods: We calculated the proportion of COVID-19 laboratory-notified cases without CN nor EI, and without EI by region and age group, in each month, from March 2020 to July 2021. We tested the correlation between those proportions and monthly case counts in two epidemic periods and used Poisson regression to identify factors associated with the outcomes. Results: The analysis included 909,720 laboratory-notified cases. After October 2020, an increase in the number of COVID-19 cases was associated with a decrease in the submissions of CN and EI. By July 2021, 68.57% of cases had no associated CN nor EI, and 96.26% had no EI. Until January 2021, there was a positive correlation between monthly case counts and the monthly proportion of cases without CN nor EI and without EI, but not afterward. Cases aged 75 years or older had a lower proportion without CN nor EI (aRR: 0.842 CI95% 0.839-0.845). When compared to the Norte region, cases from Alentejo, Algarve, and Madeira had a lower probability of having no EI (aRR;0.659 CI 95%0.654-0.664; aRR 0.705 CI 95% 0.7-0.711; and aRR 0.363 CI 95% 0.354-0.373, respectively). Discussion: After January 2021, CN and EI were submitted in a small proportion of laboratory-confirmed cases, varying by age and region. Facing the large number of COVID-19 cases, public health services may have adopted other registry strategies including new surveillance and management tools to respond to operational needs. This may have contributed to the abandonment of official CN and EI submission. Useful knowledge on the context of infection, symptom profile, and other knowledge gaps was no longer adequately supported by SINAVE. Regular evaluation of pandemic surveillance systems' completeness is necessary to inform surveillance improvements and procedures considering dynamic objectives, usefulness, acceptability, and simplicity.

The Association Between Chronic Disease and Serious COVID-19 Outcomes and Its Influence on Risk Perception: Survey Study and Database Analysis.

BACKGROUND: COVID-19, a viral respiratory disease first reported in December 2019, quickly became a threat to global public health. Further understanding of the epidemiology of the SARS-CoV-2 virus and the risk perception of the community may better inform targeted interventions to reduce the impact and spread of COVID-19. OBJECTIVE: In this study, we aimed to examine the association between chronic diseases and serious outcomes following COVID-19 infection, and to explore its influence on people's self-perception of risk for worse COVID-19 outcomes. METHODS: This study draws data from two databases: (1) the nationwide database of all confirmed COVID-19 cases in Portugal, extracted on April 28, 2020 (n=20,293); and (2) the community-based COVID-19 Barometer survey, which contains data on health status, perceptions, and behaviors during the first wave of COVID-19 (n=171,087). We assessed the association between relevant chronic diseases (ie, respiratory, cardiovascular, and renal diseases; diabetes; and cancer) and death and intensive care unit (ICU) admission following COVID-19 infection. We identified determinants of self-perception of risk for severe COVID-19 outcomes using logistic regression models. RESULTS: Respiratory, cardiovascular, and renal diseases were associated with mortality and ICU admission among patients hospitalized due to COVID-19 infection (odds ratio [OR] 1.48, 95% CI 1.11-1.98; OR 3.39, 95% CI 1.80-6.40; and OR 2.25, 95% CI 1.66-3.06, respectively). Diabetes and cancer were associated with serious outcomes only when considering the full sample of COVID-19-infected cases in the country (OR 1.30, 95% CI 1.03-1.64; and OR 1.40, 95% CI 1.03-1.89, respectively). Older age and male sex were both associated with mortality and ICU admission. The perception of risk for severe COVID-19 disease in the study population was 23.9% (n=40,890). This was markedly higher for older adults (n=5235, 46.4%), those with at least one chronic disease (n=17,647, 51.6%), or those in both of these categories (n=3212, 67.7%). All included diseases were associated with self-perceptions of high risk in this population. CONCLUSIONS: Our results demonstrate the association between some prevalent chronic diseases and increased risk of worse COVID-19 outcomes. It also brings forth a greater understanding of the community's risk perceptions of serious COVID-19 disease. Hence, this study may aid health authorities to better adapt measures to the real needs of the population and to identify vulnerable individuals requiring further education and awareness of preventive measures.

Valoración Geriátrica Integral de pacientes mayores y factores asociados de frecuentación en servicios de urgencias en la Era pre-covid19 - Un estudio português Comprehensive geriatric assessment of older patients and associated factors of admission to Emergency Departments in pre-covid 19 Era – a Portuguese study

Objetivos: Identificar factores asociados con usuarios frecuentadores (≥3 ingresos/año) en un departamento de urgencias (DU), mediante valoración geriátrica integral (VGI) y describir las características de los pacientes mayores de 65 años que acuden a urgencias. Métodos: El estudio transversal se realizó entre Agosto/2017 y Junio/2018 en un DU de Lisboa, Portugal. Se realizó una VGI además de la historia clínica. Se crearon scores clínicas, funcionales, mentales, sociales basándose en el protocolo de cuestionario del grupo de geriatría de la Sociedad Portuguesa de Medicina Interna y se desarrolló un modelo estadístico para identificar los factores asociados con la alta frecuentación. Resultados: Se realizó una VGI a 426 usuarios mayores de un DU. La edad media fue de 79.3 años, siendo 53,8% mujeres con un 84.7% de multimorbilidad, 51,2% de dependencia de las actividades básicas (KATZ), 75,6% instrumentales (Lawton < 5 en mujeres, <3 hombres y 40% de dependencia de la marcha (Holden). El 52% tenían síntomas depresivos (Yessavage), 65.7% tenían deterioro cognitivo (MMSE <24), 63% estaban desnutridos / en riesgo de desnutrición (MNA < 23,5) El 33,1% estaba en riesgo social (Gijón, APGAR familiar). La polifarmacia con el uso de un promedio de 6.5 medicamentos al día. Los scores sociales, clínicas, funcionales y mentales fueron adversos en el 48,6%, 79,6%, 54,9% y 83,1%, respectivamente. Hubo 2,7 admisiones/año y el 39,9% eran usuarios frecuentes de DU (≥3/year). Un modelo de regresión logística fue débil, pero mostró que los pacientes con polifarmacia, índice de comorbilidad de Charlson elevado y un estado nutricional adverso presentaban mayor riesgo de ser usuarios frecuentes. Conclusiones: El 97,1% de los pacientes tenían necesidades que justificarían un plan de intervención específico. Si bien no proporciona un modelo sólido, nuestro estudio ha indicado problemas nutricionales, polifarmacia y un índice de Charlson elevado como las características que se asocian con ser frecuentador del servicio de urgências.

Association between perception of COVID-19 risk, confidence in health services and avoidance of emergency department visits: results from a community-based survey in Portugal.

OBJECTIVES: To examine the association between the perception of COVID-19 risk, confidence in health services and avoidance of emergency department (ED) visits in Portugal during the COVID-19 pandemic. DESIGN: Community-based, cross-sectional survey. SETTING: Volunteer sample that completed the online survey between April 2020 and May 2021. PARTICIPANTS: 987 participants who perceived needing ED care. Of those, 242 reported avoiding ED visits. OUTCOME MEASURES: Logistic regression models for ED avoidance were conducted to estimate the effect of risk perception and confidence in health services, adjusted for sociodemographics, health status and time. RESULTS: The adjusted odds for ED avoidance were higher for participants lacking confidence in health service response to non-COVID-19 conditions (adjusted OR: 6.39; 95% CI 3.19 to 12.82) and COVID-19 (1.81; 1.19 to 2.77) and lower for those perceiving a low risk of being infected at a health provider (0.16; 0.07 to 0.38). CONCLUSION: In our sample, confidence in health services and risk perception of infection at a health provider were associated with the decision to avoid the ED. These results suggest that policymakers and care providers need to mitigate the negative consequences of delayed healthcare; be aware of the implications of distrust and fear from those in need of healthcare and provide equally distributed safe alternatives to ED care.

Factors Associated with COVID-19 Vaccine Hesitancy after Implementation of a Mass Vaccination Campaign.

An online cross-sectional study on COVID-19 vaccination adhesion was conducted in Portugal nine months after vaccination rollout (September-November 2021). Logistic regression was used to identify factors associated with hesitancy to take the COVID-19 vaccine in the community-based survey, "COVID-19 Barometer: Social Opinion". Hesitancy was 11%; however, of those, 60.5% stated that they intended to take the vaccine. Hesitancy was associated with factors such as lower monthly household income; no intention of taking the flu vaccine this year; perceived reasonable health status; having two or more diseases; low confidence in the health service response; worse perception of the adequacy of anti-COVID-19 government measures; low or no perceived risk of getting COVID-19; feeling agitated, anxious or sad some days; and lack of trust in the safety and efficacy of the vaccines. Confidence in vaccines, namely against COVID-19, is paramount for public health and should be monitored during vaccination rollout. Clear communication of the risks and benefits of vaccination needs improvement to increase adherence and public confidence.

Monitoring of SARS-CoV-2 Specific Antibodies after Vaccination.

Vaccination is considered the most important measure to control the COVID-19 pandemic. Extensive follow-up studies with distinct vaccines and populations are able to promote robust and reliable data to better understand the effectiveness of this pharmacologic strategy. In this sense, we present data regarding binding and neutralizing (achieved by surrogate ELISA assay) antibodies throughout time, from vaccinated and previously infected (PI) health care workers (HCW) in Portugal. We analyzed serum samples of 132 HCW, who were vaccinated and with previous SARS-CoV-2 infection. Samples were collected before vaccination (baseline, M1), at second dose vaccine uptake (M2), and 25-70 days (M3) and 150-210 days (M4) after the second dose for vaccinated individuals. The IgG (anti-RBD/S) antibody geometric mean titers found on vaccinated HCW at M2 (GM = 116.1 BAU/mL; CI: 92.3-146.1) were significantly higher than those found on PI HCW at recruitment (M1) (GM = 35.9 BAU/mL; CI:15.4-83.4), and the neutralizing antibodies (nAb) were similar between these groups, of 93.2 UI/mL (95% CI 73.2-118.5) vs. 84.1 UI/mL (95% CI 40.4-155.9), respectively. We detected around 10-fold higher IgG (anti-RBD/S) antibodies titers in M3 when compared with M2, with a slight but significant decrease in titers from 36 days after the second dose vaccine uptake. The increase of nAb titers was correlated with IgG (anti-RBD/S) antibodies titers; however, in contrast to IgG (anti-RBD/S) antibodies titers, we did not detect a decrease in the nAb titer 36 days after a second vaccine dose uptake. At M4, a decrease of 8-fold in binding IgG (anti-RBD/S) and nAb was observed. No significant differences in antibody titers were observed by sex, age or chronic diseases. Our results suggest that IgG (anti-RBD/S) antibodies titers and nAb titers could be correlated, but an ongoing follow up of the cohort is required to better understand this correlation, and the duration of the immune response.

Factors Associated with the Patient's Decision to Avoid Healthcare during the COVID-19 Pandemic.

The COVID-19 pandemic has resulted in changes in healthcare use. This study aimed to identify factors associated with a patient's decision to avoid and/or delay healthcare during the COVID-19 pandemic. We used data from a community-based survey in Portugal from July 2020 to August 2021, "COVID-19 Barometer: Social Opinion", which included data regarding health services use, risk perception and confidence in health services. We framed our analysis under Andersen's Behavioural Model of Health Services Use and utilised Poisson regression to identify healthcare avoidance associated factors. Healthcare avoidance was high (44%). Higher prevalence of healthcare avoidance was found among women; participants who reported lower confidence in the healthcare system response to COVID-19 and non-COVID-19; lost income during the pandemic; experienced negative emotions due to physical distancing measures; answered the questionnaire before middle June 2021; and perceived having worse health, the measures implemented by the Government as inadequate, the information conveyed as unclear and confusing, a higher risk of getting COVID-19, a higher risk of complications and a higher risk of getting infected in a health institution. It is crucial to reassure the population that health services are safe. Health services should plan their recovery since delays in healthcare delivery can lead to increased or worsening morbidity, yielding economic and societal costs.

A Case-Control Study of Contextual Factors for SARS-CoV-2 Transmission.

Background: Knowledge on the settings and activities associated with a higher risk of SARS-CoV-2 transmission is essential to inform decision-making. We thus designed a case-control study to identify relevant settings for community transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Portugal. Methods: We evaluated 1,088 cases, identified through the national surveillance system, and 787 community controls, recruited using random digit dialing. Sociodemographic characteristics, individual protective measures, and activities or visited settings were obtained through telephone interview. We report sex-, age-, education-, and citizenship-adjusted odds ratios (aOR) with 95% confidence intervals (95% CI). Results: Household overcrowding (aOR = 1.47; 95% CI 1.14-1.91) and work in senior care (4.99; 1.30-33.08) increased while working remotely decreased the risk of infection (0.30; 0.22-0.42). Going to restaurants/other dining spaces (0.73; 0.59-0.91), grocery stores (0.44; 0.34-0.57) or hair salons (0.51; 0.39-0.66), or the use of public transportation did not present a higher risk of infection (0.98; 0.75-1.29), under existing mitigation strategies. Lower education ( ≤ 4 years vs. tertiary education: 1.79; 1.33-2.42) and no Portuguese citizenship (5.47; 3.43-9.22) were important risk factors. Conclusions: The utilization of public transportation, restaurants, and commercial spaces was not associated with increased risk of infection, under capacity restrictions, physical distancing, use of masks, and hygiene measures. Overcrowding, foreign citizenship, low education and working on-site were positively associated with SARS-CoV-2 infection.

Double jeopardy from the COVID-19 pandemic: risk of exposure and income loss in Portugal.

BACKGROUND: Increasing evidence indicates that the first wave of the COVID-19 pandemic had immediate health and social impact, disproportionately affecting certain socioeconomic groups. Assessing inequalities in risk of exposure and in adversities faced during the pandemic is critical to inform targeted actions that effectively prevent disproportionate spread and reduce social and health inequities. This study examines i) the socioeconomic and mental health characteristics of individuals working in the workplace, thus at increased risk of COVID-19 exposure, and ii) individual income losses resulting from the pandemic across socioeconomic subgroups of a working population, during the first confinement in Portugal. METHODS: This study uses data from 'COVID-19 Barometer: Social Opinion', a community-based online survey in Portugal. The sample for analysis comprised n = 129,078 workers. Logistic regressions were performed to estimate the adjusted odds ratios (AOR) of factors associated with working in the workplace during the confinement period and with having lost income due to the pandemic. RESULTS: Over a third of the participants reported working in the workplace during the first confinement. This was more likely among those with lower income [AOR = 2.93 (2.64-3.25)], lower education [AOR = 3.17 (3.04-3.30)] and working as employee [AOR = 1.09 (1.04-1.15)]. Working in the workplace was positively associated with frequent feelings of agitation, anxiety or sadness [AOR = 1.14 (1.09-1.20)] and perception of high risk of infection [AOR = 11.06 (10.53-11.61)]. About 43% of the respondents reported having lost income due to the pandemic. The economic consequences affected greatly the groups at increased risk of COVID-19 exposure, namely those with lower education [AOR = 1.36 (1.19-1.56)] and lower income [AOR = 3.13 (2.47-3.96)]. CONCLUSIONS: The social gradient in risk of exposure and in economic impact of the pandemic can result in an accumulated vulnerability for socioeconomic deprived populations. The COVID-19 pandemic seems to have a double effect in these groups, contributing to heightened disparities and poor health outcomes, including in mental health. Protecting the most vulnerable populations is key to prevent the spread of the disease and mitigate the deepening of social and health disparities. Action is needed to develop policies and more extensive measures for reducing disproportionate experiences of adversity from the COVID-19 pandemic among most vulnerable populations.

Lower prevalence of congenital cytomegalovirus infection in Portugal: possible impact of COVID-19 lockdown?

Cytomegalovirus (CMV) is the most frequent cause of congenital infection all over the world. Its prevalence ranges from 0.2 to 2.2%. Transmission from children to their pregnant mothers is a well-known risk factor, particularly if they attend a childcare centre. This study aims to compare the prevalence of CMV congenital infection (CMV_CI) in Portugal (Lisbon) between two studies, performed respectively in 2019 and 2020. In the 2019 study, performed in two hospitals, we found a 0.67% CMV_CI prevalence, using a pool strategy previously tested with saliva samples. In the 2020 study, using the same pool approach in four hospitals (the previous and two additional), and based on 1277 samples, the prevalence was 0.078%.Conclusion: The close temporal coincidence with COVID-19 lockdown suggests that these measures may have had a significant impact on this reduction, although other explanations cannot be ruled-out. What is Known: • Cytomegalovirus is the leading cause of congenital infection. • Behavioural measures decrease cytomegalovirus seroconversion in pregnant women. What is New: • From 2019 to 2020 there was a significant reduction in the prevalence of congenital CMV infection.

Determinants for hospitalisations, intensive care unit admission and death among 20,293 reported COVID-19 cases in Portugal, March to April 2020.

BackgroundDeterminants of hospitalisation, intensive care unit (ICU) admission and death are still unclear for COVID-19. Few studies have adjusted for confounding for different clinical outcomes including all reported cases within a country.AimWe used routine surveillance data from Portugal to identify risk factors for severe COVID-19 outcomes, and to support risk stratification, public health interventions, and planning of healthcare resources.MethodsWe conducted a retrospective cohort study including 20,293 laboratory-confirmed cases of COVID-19 reported between 1 March and 28 April 2020 through the national epidemiological surveillance system. We calculated absolute risk, relative risk (RR) and adjusted relative risk (aRR) to identify demographic and clinical factors associated with hospitalisation, ICU admission and death using Poisson regressions.ResultsIncreasing age (≥ 60 years) was the major determinant for all outcomes. Age ≥ 90 years was the strongest determinant of hospital admission (aRR: 6.1), and 70-79 years for ICU (aRR: 10.4). Comorbidities of cardiovascular, immunodeficiency, kidney and lung disease (aRR: 4.3, 2.8, 2.4, 2.0, respectively) had stronger associations with ICU admission, while for death they were kidney, cardiovascular and chronic neurological disease (aRR: 2.9, 2.6, 2.0).ConclusionsOlder age was the strongest risk factor for all severe outcomes. These findings from the early stages of the COVID-19 pandemic support risk-stratified public health measures that should prioritise protecting older people. Epidemiological scenarios and clinical guidelines should consider this, even though under-ascertainment should also be considered.

Years of life lost by COVID-19 in Portugal and comparison with other European countries in 2020.

BACKGROUND: The impact of the COVID-19 pandemic has been measured in different metrics, mostly by counting deaths and its impact on health services. Few studies have attempted to calculate years of life lost (YLL) to COVID-19 and compare it with YLL due to other causes in different countries. METHODS: We calculated YLL to COVID-19 from week10 to week52 in 2020 for eight European countries by methods defined by the WHO. We calculated excess YLL by subtracting the average YLL from 2017 to 2019 to the YLL in 2020. Our analysis compared YLL to COVID-19 and the excess YLL of non-COVID-19 causes across countries in Europe. RESULTS: Portugal registered 394,573 cases and 6619 deaths due to COVID-19, accounting for 25,395 YLL in just 10 months. COVID-19 was responsible for 6.7% of all deaths but accounted for only 4.2% of all YLL. We estimate that Portugal experienced an excess of 35,510 YLL (+ 6.2%), of which 72% would have been due to COVID-19 and 28% due to non-COVID-19 causes. Spain, Portugal, and the Netherlands experienced excess YLL to non-COVID-19 causes. We also estimated that Portugal experienced an excess of 10,115 YLL due to cancer (3805), cardiovascular diseases (786) and diseases of the respiratory system (525). CONCLUSION: COVID-19 has had a major impact on mortality rates in Portugal, as well as in other European countries. The relative impact of COVID-19 on the number of deaths has been greater than on the number of YLL, because COVID-19 deaths occur mostly in advanced ages.

Factors Associated with COVID-19 Vaccine Hesitancy.

It is critical to develop tailored strategies to increase acceptability of the COVID-19 vaccine and decrease hesitancy. Hence, this study aims to assess and identify factors associated with COVID-19 vaccine hesitancy in Portugal. We used data from a community-based survey, "COVID-19 Barometer: Social Opinion", which includes data regarding intention to take COVID-19 vaccines, health status, and risk perception in Portugal from September 2020 to January 2021. We used multinomial regression to identify factors associated with intention to delay or refuse to take COVID-19 vaccines. COVID-19 vaccine hesitancy in Portugal was high: 56% would wait and 9% refuse. Several factors were associated with both refusal and delay: being younger, loss of income during the pandemic, no intention of taking the flu vaccine, low confidence in the COVID-19 vaccine and the health service response during the pandemic, worse perception of government measures, perception of the information provided as inconsistent and contradictory, and answering the questionnaire before the release of information regarding the safety and efficacy of COVID-19 vaccines. It is crucial to build confidence in the COVID-19 vaccine as its perceived safety and efficacy were strongly associated with intention to take the vaccine. Governments and health authorities should improve communication and increase trust.

Evolution of inequalities in the coronavirus pandemics in Portugal: an ecological study.

BACKGROUND: Previous literature shows systematic differences in health according to socioeconomic status (SES). However, there is no clear evidence that the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection might be different across SES in Portugal. This work identifies the coronavirus disease 2019 (COVID-19) worst-affected municipalities at four different time points in Portugal measured by prevalence of cases, and seeks to determine if these worst-affected areas are associated with SES. METHODS: The worst-affected areas were defined using the spatial scan statistic for the cumulative number of cases per municipality. The likelihood of being in a worst-affected area was then modelled using logistic regressions, as a function of area-based SES and health services supply. The analyses were repeated at four different time points of the COVID-19 pandemic: 1 April, 1 May, 1 June, and 1 July, corresponding to two moments before and during the confinement period and two moments thereafter. RESULTS: Twenty municipalities were identified as worst-affected areas in all four time points, most in the coastal area in the Northern part of the country. The areas of lower unemployment were less likely to be a worst-affected area on the 1 April [adjusted odds ratio (AOR) = 0.36 (0.14-0.91)], 1 May [AOR = 0.03 (0.00-0.41)] and 1 July [AOR = 0.40 (0.16-1.05)]. CONCLUSION: This study shows a relationship between being in a worst-affected area and unemployment. Governments and public health authorities should formulate measures and be prepared to protect the most vulnerable groups.

Population-based Estimates for High Risk of Severe COVID-19 Disease due to Age and Underlying Health Conditions.

INTRODUCTION: COVID-19 is a viral respiratory disease, which became a global threat to public health. Specific subsets of the population are more vulnerable, namely those with chronic diseases. We aimed to estimate the share of the Portuguese population at the highest risk for complications following COVID-19 infection due to both old age and specific comorbidities. MATERIAL AND METHODS: Our sample included all people aged 65 years and above (2215 men and 3486 women) who participated in the fifth Portuguese National Health Interview Survey, conducted in 2014. In order to project the potential population at highest risk for COVID-19, we used the latest available official demographic estimates from the National Institute of Statistics - INE 2018. We used a more restrictive definition of risk combining old age criteria and the following chronic conditions as potential risk factors for COVID-19 according to the available literature: hypertension, diabetes, chronic obstructive pulmonary disease, cardio- and cerebrovascular disease. RESULTS: We estimated that 15.5% (n = 1 560 667) of the Portuguese population might be at increased risk for complications from COVID-19 because of old age and existing chronic conditions. Such estimates vary across the country (from 1.7% in Azores to 33.7% in Northern Portugal). Northern Portugal not only has the highest prevalence of selected morbidity (72.8%) within mainland Portugal, but also has the largest population at risk for COVID-19 (n = 526 607). This was followed by the Lisbon and Tagus Valley region (n = 408 564) and Central Portugal (n = 388 867). DISCUSSION: Our results should encourage authorities to continue protecting those more vulnerable to the pandemic threat, particularly on those areas of the country which are more likely to be further affected. CONCLUSION: We projected a considerable number of Portuguese people at the highest risk for severe COVID-19 disease due to both old age and pre-existing chronic conditions. Such estimates vary across the country.

Vigilância Epidemiológica do COVID-19: considerações sobre incerteza e sub-deteção

Epidemic surveillance is a fundamental part of public health practice. Addressing under-ascertainment of cases is relevant in most surveillance systems, especially in pandemics of new diseases with a large spectrum of clinical presentations as it may influence timings of policy implementation and public risk perception. From this perspective, this article presents and discusses early evidence on under-ascertainment of COVID-19 and its motifs, options for surveillance, and reflections around their importance to tailor public health measures. In the case of COVID-19, systematically addressing and estimating under-ascertainment of cases is essential to tailor timely public health measures, and communicating these findings is of the utmost importance for policy making and public perception.