Impact of Lifting Mask Mandates on COVID-19 Incidence and Mortality in Portugal: An Ecological Study.

INTRODUCTION: The use of face masks in public was one of several COVID-19 non-pharmaceutical interventions adopted to mitigate the pandemic in Portugal. The aim of this study was to evaluate the impact of lifting the mask mandate on the April 22, 2022 on COVID-19 incidence and mortality in mainland Portugal and in the Azores. As a secondary objective, we aimed to evaluate the evolution of COVID-19 cases in a setting without a mask mandate (Azores islands) and in a setting with a mask mandate (Madeira islands). MATERIAL AND METHODS: Surveillance data on laboratory-confirmed COVID-19 cases and COVID-19 deaths were used to conduct an interrupted time series analysis to estimate changes in daily incidence and deaths during a mask mandate period (28th March - 21st April 2022) and during a post-mask mandate period (22nd April - 15th May 2022), in mainland Portugal and the Azores. In a second phase, for each group of islands, we fitted a negative binomial regression model, with daily COVID-19 incident cases as the primary outcome of interest, and relative frequency of Omicron BA.5 lineage as explanatory variable. RESULTS: Significant changes in trends were observed for the overall incidence rate and COVID-19 deaths; increasing trends were observed for COVID-19 incidence and deaths in the post mandate period [5.3% per day; incidence rate ratio (IRR): 1.053; 95% confidence interval (CI): 1.029 - 1.078] and [3.2% per day; mortality rate ratio (MRR): 1.032; 95% CI: 1.003 - 1.062], respectively. For every unit increase in the percentage of Omicron BA.5 lineage there was a 1.5% increase per day (IRR: 1.015; 95% CI: 1.006 - 1.024) in COVID-19 incidence rate in the Azores islands, while for Madeira islands an increase of 0.05% COVID-19 cases per day was observed (IRR: 1.005; 95% CI: 1.000 - 1.010). CONCLUSION: Lifting the mask mandate in Portugal was associated with an increase in COVID-19 incidence and deaths, thus highlighting the positive effect of face mask policies in preventing respiratory virus transmission and saving lives.

Monitoring COVID-19 and Influenza: The Added Value of a Severe Acute Respiratory Infection Surveillance System in Portugal.

Background: Severe acute respiratory infections (SARI) surveillance is recommended to assess the severity of respiratory infections disease. In 2021, the National Institute of Health Doutor Ricardo Jorge, in collaboration with two general hospitals, implemented a SARI sentinel surveillance system based on electronic health registries. We describe its application in the 2021/2022 season and compare the evolution of SARI cases with the COVID-19 and influenza activity in two regions of Portugal. Methods: The main outcome of interest was the weekly incidence of patients hospitalized due to SARI, reported within the surveillance system. SARI cases were defined as patients containing ICD-10 codes for influenza-like illness, cardiovascular diagnosis, respiratory diagnosis, and respiratory infection in their primary admission diagnosis. Independent variables included weekly COVID-19 and influenza incidence in the North and Lisbon and Tagus Valley regions. Pearson and cross-correlations between SARI cases, COVID-19 incidence and influenza incidence were estimated. Results: A high correlation between SARI cases or hospitalizations due to respiratory infection and COVID-19 incidence was obtained (ρ = 0.78 and ρ = 0.82, respectively). SARI cases detected the COVID-19 epidemic peak a week earlier. A weak correlation was observed between SARI and influenza cases (ρ = -0.20). However, if restricted to hospitalizations due to cardiovascular diagnosis, a moderate correlation was observed (ρ = 0.37). Moreover, hospitalizations due to cardiovascular diagnosis detected the increase of influenza epidemic activity a week earlier. Conclusion: In the 2021/2022 season, the Portuguese SARI sentinel surveillance system pilot was able to early detect the COVID-19 epidemic peak and the increase of influenza activity. Although cardiovascular manifestations associated with influenza infection are known, more seasons of surveillance are needed, to confirm the potential use of cardiovascular hospitalizations as an indicator of influenza activity.

SARS-CoV-2 Seroprevalence Following a Large-Scale Vaccination Campaign in Portugal: Results of the National Serological Survey, September - November 2021.

INTRODUCTION: Following a COVID-19 mass vaccination campaign, it is important to evaluate the population level of SARS-CoV-2 antibodies. The aim of this study was to estimate the seroprevalence rate of SARS-CoV-2 specific antibodies acquired due to infection or vaccination in the Portuguese population. MATERIAL AND METHODS: The National Serological Survey (third wave - ISN3COVID-19) is a cross-sectional nationwide epidemiological study developed on a sample of 4545 Portuguese residents aged one year or older, between the 28th September 2021 and the 19th November 2021. The SARS-CoV-2 anti-nucleoprotein and anti-spike IgG antibody levels were determined in serum samples using Abbott Chemiluminescent Microparticle Immunoassays. Seroprevalence estimates were stratified by age group, sex, administrative region and self-reported chronic conditions. Medians and respective 95% confidence intervals were used to describe the distribution of SARS-CoV-2 specific antibodies in specific population subgroups. RESULTS: The total seroprevalence rate of SARS-CoV-2 was 86.4% (95% CI: 85.2% to 87.6%). A higher seroprevalence rate was estimated for women (88.3%), 50 to 59 years-old (96.5%) and in those with two or more self-reported chronic conditions (90.8%). A higher IgG (anti-Spike) concentration was observed in individuals vaccinated with the booster dose (median = 1 2601.3 AU/mL; 95% CI: 4127.5 to 19 089.1). CONCLUSION: There was a significant increase in SARS-CoV-2 seroprevalence following the mass vaccination campaign in Portugal. It is important to continue to monitor the distribution of specific SARS-COV-2 antibody at the population level to further inform public health policies.

Resurgence of Respiratory Syncytial Virus in Children: An Out-of-Season Epidemic in Portugal.

INTRODUCTION: An out-of-season increase in respiratory syncytial virus (RSV) incidence was observed in Portugal from June 2021 onwards, revealing a continuing surge in cases throughout 2021/2022 autumn/winter. We aimed to describe this out-of-season epidemic and define its epidemic period, by analysing RSV incidence from week 40 of 2020 (2020-W40) to week 18 of 2022 (2022-W18). MATERIAL AND METHODS: Surveillance data on weekly RSV laboratory confirmed cases, in Portugal, was used to monitor RSV incidence using CUSUM test methodology for count data. RESULTS: In 2021-W23, the CUSUM score identified a significant increase in the risk of RSV. By that time, the percentage of RSV positive tests rose from 1% in 2021-W22 (3/265) to 6% in 2021-W23 (18/298). Despite a sharp decrease in RSV incidence on 2021-W33 and on 2022-W02, the CUSUM score stayed over the limit up to 2022-W07, indicating that the RSV activity remained at an epidemic level. Distinct peaks of RSV cases were observed between 2021-W30 and 2021-W32 (average of 77 RSV cases per week) and between 2021-W39 and 2021-W41 (average of 79 RSV cases per week) with positivity rates around 60%. CONCLUSION: An out-of-season RSV epidemic was identified, with a longer epidemic period compared with previous seasons. Possible reasons include relaxation of COVID-19 physical distancing measures and a greater proportion of population susceptible to disease. As several factors may change the pattern of RSV activity, countries should implement year-round surveillance RSV surveillance systems. These findings might have an impact on public health planning regarding future RSV surges, namely, on the palivizumab prophylaxis period for high-risk infants.

Impact of stringent non-pharmaceutical interventions applied during the second and third COVID-19 epidemic waves in Portugal, 9 November 2020 to 10 February 2021: an ecological study.

BackgroundNon-pharmaceutical interventions (NPIs) were implemented worldwide to control the spread of SARS-CoV-2.AimTo evaluate the impact of tiered NPIs and a nationwide lockdown on reduction of COVID-19 incidence during the second and third epidemic waves in Portugal.MethodsSurveillance data on laboratory-confirmed COVID-19 cases were used to conduct an interrupted time series analysis to estimate changes in daily incidence during a second wave tiered NPI period (9 November-18 December 2020), and a third wave lockdown period without (15-21 January 2021) and with school closure (22 January-10 February 2021).ResultsSignificant changes in trends were observed for the overall incidence rate; declining trends were observed for tiered NPIs (-1.9% per day; incidence rate ratio (IRR): 0.981; 95% confidence interval (CI): 0.973-0.989) and a lockdown period without (-3.4% per day; IRR: 0.966; 95% CI: 0.935-0.998) and with school closure (-10.3% per day, IRR: 0.897; 95% CI: 0.846-0.951). Absolute effects associated with tiered NPIs and a lockdown on a subsequent 14-day period yielded 137 cases and 437 cases per 100,000 population potentially averted, respectively.ConclusionOur results indicate that tiered NPIs implemented during the second wave caused a decline in COVID-19 incidence, although modest. Moreover, a third wave lockdown without school closure was effective in reducing COVID-19 incidence, but the addition of school closure provided the strongest effect. These findings emphasise the importance of early and assertive decision-making to control the pandemic.

SARS-CoV-2 seroprevalence in Portugal following the third epidemic wave: results of the second National Serological Survey (ISN2COVID-19).

BACKGROUND: Integrated approaches to surveillance of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection are important for public health actions. The 2nd National Serological Survey (ISN2COVID-19) aimed to characterize the extent of SARS-CoV-2 infection and vaccine-induced response in the Portuguese population following the third epidemic wave and the launch of the vaccination campaign. METHODS: A cross-sectional study was performed using data on 8463 Portuguese 1-79 years of age, collected in February and March, 2021. SARS-CoV-2 IgM and IgG (anti-nucleoprotein and anti-spike) antibodies were determined in serum samples using Abbott Architect chemiluminescent microparticle assays. Post-infection and vaccine-induced seroprevalence with 95% confidence intervals (95%CI) were estimated in the overall sample and stratified by population characteristics. RESULTS: The estimated seroprevalence was 15.5% (95%CI:14.6-16.5%), of which 13.5% (95%CI: 12.6-14.4%) was attributable to natural infection and 2.0% (95%CI:1.7-2.4%) to vaccination. The lowest seroprevelence was observed in persons aged 70-79 years (8.9% 95%CI:6.8-11.6), while seroprevalence in children (14.3%; 95%CI:11.5-17.6%) and adolescents (12.9%; 95%CI:10.5-15.7%) was similar to that of persons aged between 20 and 69 years. Of seropositive individuals, 22.6% (95%CI:19.7-25.9%) did not report any symptoms in 6 months prior to interview. Of persons with completed vaccination (2-doses), 98.6% (95%CI: 93.0-99.7%) had specific IgG (anti-S) antibodies. CONCLUSIONS: After the third epidemic wave, the post-infection SARS-CoV-2 seroprevalence was 1.7 times higher than the cumulative incidence based on PCR-testing, but was higher (2.7 times) in children may be due to the high proportion of asymptomatic and mild infections.

[Early Detection of COVID-19 in Portugal: Use of Clinical Records]. / Deteção Precoce de COVID-19 em Portugal: Uso de Registos Clínicos.

INTRODUCTION: Syndromic surveillance allows early detection of changes in the population's morbidity pattern. The aim of this study is to evaluate the usefulness of indicators related to access to healthcare services, in COVID-19 surveillance. MATERIAL AND METHODS: A time series analysis was performed using the weekly incidence rate of COVID-19 in Mainland Portugal, between weeks 14/2020 (March 30 to April 5) and 25/2020 (June 15 to 21), and six indicators: 1) COVID-19 consultations in primary healthcare; 2) number of COVID-19 emergency department visits; 3) number of emergency department visits due to viral pneumonia; 4) number of hospitalizations due to viral pneumonia; 5) proportion of emergency department visits due to viral pneumonia; and 6) proportion of hospitalizations for viral pneumonia. Pearson correlation and cross-correlations were computed. RESULTS: A strong correlation was found between the weekly incidence rate of COVID-19 and all indicators. [(1) 0.76; (2) 0.82; (3) 0.77; (4) 0.84; (5) 0.86; e (6) 0.90]. Emergency department visits and hospitalizations for viral pneumonia detect variations in the frequency of the disease with a one week lag compared to the incidence rate of COVID-19, in one week. COVID-19 consultations in primary healthcare and emergency department visits trail behind the incidence rate of COVID-19, in one week. The proportion of viral pneumonias in emergency department visits, or hospitalizations, is temporally aligned with the weekly incidence rate of COVID-19. DISCUSSION: The delay found in the COVID-19 primary healthcare consultations and emergency department visits, may be related to changes in access to healthcare services and clinical coding. Emergency department visits and hospitalizations for viral pneumonia may be useful in the early detection of COVID-19. Viral pneumonia may have been coded as being of unknown origin. Future monitoring of these indicators is necessary to ascertain whether the incidence of COVID-19 is significantly influenced by changes in testing strategies. The indicators described in this study will be an asset for the optimization of testing strategies, allocation of healthcare resources to the communities that are most vulnerable to severe morbidity and assessing vaccination impact. As such, surveillance systems based on clinical data will be a valuable complementary tool to SINAVE. CONCLUSION: The indicators under analysis could be used regularly, with special attention to viral pneumonias, to detect outbreaks of COVID-19. Information on pneumonia of unknown etiology may be considered in the surveillance of COVID-19.

Introdução: A vigilância sindrómica permite a identificação precoce de alterações no padrão de morbilidade da população. Este estudo tem como objetivo avaliar a utilidade de indicadores relativos a cuidados de saúde primários e hospitalares, na vigilância da COVID-19.Material e Métodos: Foi realizada uma análise de séries temporais utilizando a taxa de incidência semanal de COVID-19 em Portugal Continental, entre as semanas 14/2020 (30 março a 05 abril) e 25/2020 (15 a 21 junho), e seis indicadores: 1) consultas em cuidados de saúde primários por COVID-19; 2) número de episódios de urgência por COVID-19; 3) número de episódios de urgência por pneumonia vírica; 4) número de internamentos por pneumonia vírica; 5) proporção de episódios de urgência por pneumonia vírica face ao total de episódios de urgência por pneumonia; e 6) proporção de internamentos por pneumonia vírica face ao total de internamentos por pneumonia. Foram calculadas correlações de Pearson e correlações cruzadas.Resultados: Foi encontrada uma correlação forte entre a taxa de incidência semanal de COVID-19 e todos os indicadores [(1) 0,76; (2) 0,82; (3) 0,77; (4) 0,84; (5) 0,86; e (6) 0,90]. Os episódios de urgência e internamento por pneumonias víricas detetam variações na frequência da doença, com uma semana de antecedência. As consultas em cuidados de saúde primários e urgências por COVID-19 registam uma semana de atraso relativamente à evolução da taxa de incidência. A proporção de pneumonias víricas face ao número de pneumonias em episódios de urgência, ou internamentos, encontra-se alinhada temporalmente com a evolução da taxa de incidência semanal de COVID-19.Discussão: O atraso encontrado no padrão de evolução de consultas em CSP, e de episódios de urgência por COVID-19 face à incidência de COVID-19, poderá estar relacionado com a reorganização dos serviços de saúde e criação de códigos específicos para estas consultas. Episódios de urgência e internamentos por pneumonia vírica poderão ser úteis para a deteção precoce de possíveis surtos de COVID-19. Pneumonias víricas poderão ter sido classificadas como pneumonias de causa indeterminada. A monitorização futura destes indicadores é necessária de modo a averiguar se a incidência de COVID-19 é influenciada significativamente por alterações na estratégia de testagem. Os indicadores deste trabalho serão uma mais valia para a adequação de estratégias de testagem, alocação de recursos de saúde a comunidades mais vulneráveis à morbilidade severa e avaliação de programas de vacinação. Como tal, os sistemas de vigilância com base em registos de saúde serão um complemento valioso ao SINAVE.Conclusão: Sugere-se que os indicadores em análise sejam utilizados de forma regular, com especial atenção à informação relativa a pneumonias víricas, como forma de detetar precocemente surtos de COVID-19. A informação relativa a pneumonias de causa indeterminada poderá ser considerada na monitorização da COVID-19.