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SARS-CoV-2 serological 6-months follow-up study of a hospital-based cohort of healthcare workers following 2023 COVID-19 vaccination program
Publication . Santos, João Almeida; Gaio, Vânia; Amaral, Palmira; Henriques, Camila; Guiomar, Raquel; Machado, Ausenda
Objective: Healthcare workers (HCWs) have a higher risk of SARS-CoV-2 infection due to their direct contact with patients. On the other hand, they can also act as a source of in-hospital transmission. We assessed SARS-CoV-2 serological status of HCWs at a Portuguese central hospital before vaccination, three and six months after the 2023 COVID-19 booster vaccination program.
Methods: We conducted a serological follow-up study among a cohort of HCWs from a Portuguese central hospital, with three rounds of testing: pre-COVID-19 vaccination (September/October 2023), three months (January/February 2024), and six months (April/May 2024) post-vaccination. During follow-up, only participants who underwent pre-vaccination serology and were vaccinated were included.
SARS-CoV-2 spike receptor-binding domain (anti-RBD/S) protein-specific IgG antibodies were measured (upper limit of detection 40000 AU/mL). Descriptive statistics and Pearson Chi-Square test analysis were performed.
Results: All participants (n=177, median age: 47 years, 77,4% females) had the complete primary COVID-19 vaccination with 78,0% having received 2 additional booster doses prior to 2023 vaccination program. At pre-vaccination, all HCWs had anti-RBD/S IgG antibodies with 11,9% (n=21) presenting a concentration >40000 AU/mL. Three months later, 35,0% HCWs (n=62) underwent retesting, with 40,3% presenting anti-RBD/S IgG antibody concentrations >40000 AU/mL. After six months, 26,6% HCWs (n=47) repeated testing, with 21,3% (n=10) having antibody concentrations >40000 AU/mL. The differences in anti-RBD/S IgG antibody concentrations between the three rounds of testing were significant.
Conclusions: Three months post-COVID-19 2023 autumn vaccination, an increase in the concentration of anti-RBD/S antibodies was identified among HCW, but after six months this concentration decreased. These results are in line with the expected decay of antibodies over time after 3 months of vaccination and reinforce the importance of revaccination in HCWs.
Serological evidence of SARS-CoV-2 infection in a hospital based cohort study of healthcare workers following the 2023 COVID-19 vaccination program
Publication . Almeida Santos, João; Gaio, Vânia; Amaral, Palmira; Henriques, Camila; Guiomar, Raquel; Machado, Ausenda
Objective: Healthcare workers (HCWs) are a high-risk population to acquire SARS-CoV-2 infection and becoming a focus of transmission. It is therefore important to monitor these professionals, especially due to asymptomatic infections. The objective the study was to assess SARS-CoV-2 infection rates in healthcare professionals at a central Portuguese hospital using serological tests, three and six months after the 2023 COVID-19 booster vaccination program.
Methods: A prospective cohort study was established through serological follow-up in a cohort of healthcare professionals from a central Portuguese hospital, with three rounds of tests: pre-COVID-19 vaccination (September/October 2023), 3 months (January/February 2024) and 6 months (April/May 2024) post-vaccination. IgG antibodies specific to the SARS-CoV-2 nucleocapsid protein (anti-N) were measured. Data was analyzed trough descriptive statistics (frequency, mean, percentages) and infection rates at each testing moment (0, 3 and 6 months).
Results: At baseline, all participants (n=177, median age: 47years, 77,4% females) had the complete primary COVID-19 vaccination, with 78% having received 2 additional booster doses prior to 2023 vaccination program. Pre vaccination, 48,6% (86/177) of HCWs had detectable anti-N IgG antibodies, of which 24,4% (21/86) self-reported having had a SARS-Cov-2 infection in 2022/2023. After 3 months, 17,7% (n=11/62) had detectable anti-N IgG antibodies although being negative in the pre-vaccination testing. After 6 months, 4,3% (n=2/47) had detectable anti-N IgG antibodies but were negative in the previous two rounds.
Conclusions: During the study period, several cases of SAR-CoV-2 infection (n=13) were identified serologically among the HCW monitored, without concomitant signs and symptoms that would allow the identification of a potential infection. These results support that monitoring the infection among HCW (regardless of history of symptoms) can provide valuable information for assessing the level of exposure among hospital personnel and identifying high-risk departments. This information could allow early intervention by, for example, reminding and reinforcing the importance of personal protection standards for HCWs.
Boletim Epidemiológico Observações: Vol. 15, Nº39, jan-abr 2026
Publication . Instituto Nacional de Saúde Doutor Ricardo Jorge
Observações é uma publicação científica do INSA, IP, que visa contribuir para o conhecimento da saúde da população, os fatores que a influenciam, a decisão e a intervenção em Saúde Pública, assim como a avaliação do seu impacte na população portuguesa. Através do acesso público e gratuito a resultados científicos gerados por atividades de observação em saúde, monitorização e vigilância epidemiológica nas áreas de atuação do Instituto - Alimentação e Nutrição, Doenças Infeciosas, Genética Humana, Saúde Ambiental, Promoção da Saúde e Prevenção de Doenças Não Transmissíveis, Epidemiologia, Investigação em Serviços e Políticas de Saúde - é dada especial atenção à disseminação rápida de informação relevante para a resposta a temas de relevo para a saúde da população portuguesa, tendo como principal alvo todos os profissionais, investigadores e decisores intervenientes na área da Saúde Pública em Portugal.
A importância da consignação de receitas fiscais em saúde pública e o papel estruturante do Inquérito Nacional de Saúde com Exame Físico [Editorial]
Publication . Dias, Carlos Matias; Rodrigues, Ana Paula
A publicação em Diário da República dos Despachos n.º 2193/2026 e n.º 2230/2026 reflete decisões de política pública com significado estruturante para o sistema de saúde em Portugal. Estes instrumentos determinam a consignação de 2% da receita do imposto sobre o tabaco à execução de políticas ativas de prevenção e controlo do tabagismo, da qual 7,5% para a realização pelo Instituto Nacional de Saúde Doutor Ricardo Jorge (INSA) do Inquérito Nacional de Saúde com Exame Físico (INSEF), bem como para projetos de investigação epidemiológica e comportamental. (...)
Da tipagem clássica à genómica: reforço da vigilância de Legionella pneumophila com uma nova metodologia
Publication . Borges, Vítor; Mixão, Verónica; Rodrigues, João; Rodrigues, Raquel; Machado, Jorge; Gomes, João Paulo
Neste artigo de revisão é abordada a evolução da tipagem molecular de Legionella pneumophila, bactéria responsável pela Doença dos Legionários. São discutidas as limitações dos métodos convencionais, frequentemente insuficientes para estabelecer de forma robusta ligações entre casos humanos e fontes ambientais de contaminação, o que tem dificultado a deteção e subsequente investigação de surtos. Revisita-se a aplicação da sequenciação do genoma total (WGS) de L. pneumophila em Portugal e as suas vantagens, destacando-se o recente desenvolvimento de uma nova metodologia de análise de dados de WGS (através da bioinformática), que visa reforçar a deteção de surtos, a identificação de fontes de infeção e a avaliação de risco, apoiando o controlo atempado e efetivo de ameaças para a saúde pública a nível local e transfronteiriço.