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New variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have emerged, imposing the need for periodic booster doses. However, whether booster doses should be applied to the entire population or groups, and the booster doses interval, remains unclear. In this study, we evaluated humoral reactivity kinetics from before the first dose to 180 days after the third booster dose in different schedules in a well-controlled health worker cohort. Among the 2,506 employees, the first 500 vaccinated health workers were invited to participate. The third booster dose was administered 8 months after the first dose. Among the invited participants, 470 were included in the study; 258 received inactivated vaccine CoronaVac (VAC group) and 212 received viral vector vaccine ChAdOx1 (AZV group). The groups were homogeneous in terms of age and sex. 347 participants were followed up after the booster dose with AZV or BNT162b2 (Pfizer, BNT group): 63 with VAC/AZV, 117 with VAC/BNT, 72 with the AZV/AZV and 95 with AZV/BNT schedules. Blood samples were collected immediately before, 28 days after each dose and 180 days after the primary vaccination and booster dose. Anti-SARS-CoV-2 antibodies were measured by chemiluminescence and plaque reduction neutralization test (PRNT). Plasma immune mediators were quantified using a multiplex immunoassay. Geometric mean of antibodies increased 28 days after the second dose with 100 % seroconversion rate in both groups and decreased 180 days after the first dose. In the baseline-seropositive VAC group, the levels of plasma immune mediators increased after the second dose. Booster dose was applied at 4-6 months after the primary vaccination. Heterologous booster in VAC or AZV primary vaccinees were effective maintaining the titers of anti-SARS-CoV-2 antibodies even after 6 months of follow-up. The heterologous schedule induced higher and stable antibody reactivity, even after 180 days, protecting to ancestral (Wuhan), Delta, and Omicron variants.

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Introduction: coronavirus disease 2019 (COVID-19) is a complex multisystem disorder. It is not yet well known whether symptoms in the acute phase correlate with the duration of the immune response and the persistence of chronic symptoms.Objective: this study aimed to assess and monitor the clinical symptoms of COVID-19 and correlate them with the production of neutralizing antibodies.Methods: a cohort of 69 health workers at the University Hospital of the Federal University of Espírito Santo (HUCAM-UFES/EBSERH) diagnosed with SARS-CoV-2 infection confirmed via RT-PCR (Real-Time Reverse Transcription­Polymerase Chain Reaction) were evaluated from the onset of symptoms up to six months. SARS-CoV-2 IgG and IgM assays were used to detect the presence of IgG and IgM against the nucleocapsid protein of SARS-CoV-2 in serum samples. IgG and IgM antibody serology, pulmonary function via spirometry, and the clinical evolution of patients were performed at 15, 30, 45, 60, 90, and 180 days after the onset of COVID-19 symptoms.Results: sixty-nine health workers (age, 40 ± 10 years; 74% women) were evaluated for six months. All subjects showed mild to moderate COVID-19. The mean number of symptoms was 5.1 (± 2.3). The most common initial symptoms were muscle pain (77%), headache (75%), anosmia (70%), ageusia (64%), runny nose (59%), fever (52%), and coughing (52%). After 30 days, the patients had anosmia (18%), asthenia (18%), adynamia (14%), muscle pain (7%), and ageusia (7%). Regarding lung function, 9.25% presented with an obstructive pattern, and all recovered after six months. Of all analyzed participants, 18/69 (26%) did not have any reactive IgG or IgM values in any of the assessments. The IgG serology curve showed a peak, whereas IgM had the highest mean value on the 15th day. There was a progressive decrease and levels similar to those at baseline after 90 days, and 15/53 (28%) remained with reactive IgG after six months. Sore throat and shortness of breath were found to be independent risk factors, and patients with these symptoms were 5.9 times more likely to have reactive IgG on the 180th day. Patients with diarrhea were four times more likely to have reactive IgM.Conclusion: our findings showed that 26% of patients did not produce a humoral response post-mild COVID-19. Their antibody titers dropped significantly after 90 days, and only 28% maintained reactive IgG antibodies after six months. Sore throat and shortness of breath are predictors of a longer duration of the humoral immune response.

Introdução: a doença causada pelo coronavírus (COVID-19) é complexa e multissistêmica. Ainda não se sabe se os sintomas da fase aguda estão correlacionados com a duração da resposta imune e com a persistência dos sintomas crônicos.Objetivo: o presente estudo visa acessar e monitorar os sintomas clínicos do COVID-19, correlacionando-os com a produção de anticorpos neutralizantes.Método: uma coorte de 69 profissionais da saúde da Universidade Federal do Espírito Santo (HUCAM-UFES/EBSERH) diagnosticados com infecção por SARS-CoV-2 confirmada via RT-PCR (Real-Time Reverse Transcription-Polymerase Chain Reaction) foram avaliados do início dos sintomas até seis meses depois. Exames laboratoriais de IgG e IgM foram utilizados para detectar a presença de IgG e IgM contra a proteína do nucleocapsídeo do vírus SARS-CoV-2 nas amostras de plasma sanguíneo. Sorologia de anticorpos IgG e IgM, função pulmonar via espirometria e avaliação clínica dos pacientes foram realizadas nos dias 15, 30, 45, 60, 90 e 180 após o início dos sintomas da doença.Resultados: sessenta e nove profissionais da saúde (idade, 40 ± 10 anos; 74% mulheres) foram avaliados por seis meses. Todos apresentaram a forma leve a moderada do COVID-19. O número médio de sintomas foi 5.1 (± 2.3). O sintoma inicial mais comum foi dor muscular (77%), cefaleia (75%), anosmia (70%), ageusia (64%), coriza (59%), febre (52%), e tosse (52%). Após 30 dias, os pacientes mantiveram anosmia (18%), astenia (18%), adinamia (14%), dor muscular (7%), e ageusia (7%). Em relação à função pulmonar, 9.25% apresentaram padrão obstrutivo e todos recuperaram ao final dos seis meses. Dentre todos os participantes analisados, 18/69 (26%) não obtiveram nenhum valor de IgG e IgM considerados reagentes nos exames realizados. A curva sorológica de IgG mostrou um pico enquanto a de IgM apresentou seu maior valor médio no 15º dia. Houve um declínio progressivo e níveis similares aos basais aos 90. 15/53 (28%) permaneceram com IgG reagente após seis meses. Dor de garganta e dispneia foram considerados fatores de risco independentes, e os pacientes com esses sintomas tiveram 5,9 vezes mais chances de apresentar IgG reativa no 180º dia. Pacientes com diarreia tiveram quatro vezes mais chances de apresentar IgM reagente.Conclusão: nossos achados mostraram que 26% dos pacientes não produziram uma resposta humoral pós-COVID-19 leve. Seus títulos de anticorpos caíram significativamente após 90 dias e apenas 28% mantiveram anticorpos IgG reativos após seis meses. Dor de garganta e dispneia foram preditores de maior duração da resposta imune humoral

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BACKGROUND: This study aimed to evaluate IgG and IgM levels in COVID-19 recurrence. METHODS: The serum antibody levels and clinical data from 73 healthcare workers with SARS-CoV-2 divided into seroconverted (n=51) and non-seroconverted (n=22) groups were assessed. The presence of specific anti-nucleocapsid (anti-N) IgM and IgG for SARS-CoV-2 was evaluated. IgG antibodies to the SARS-CoV-2 spike receptor-binding domain were used to confirm non-seroconversion in all negative anti-N. RESULTS: Four recurrent cases displayed mild symptoms and were non-seroconverted until the recurrence of symptoms. CONCLUSIONS: Undetectable anti-nucleocapsid IgM and IgG levels may be correlated with symptomatic COVID-19 recurrence.

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ABSTRACT Background: This study aimed to evaluate IgG and IgM levels in COVID-19 recurrence. Methods: The serum antibody levels and clinical data from 73 healthcare workers with SARS-CoV-2 divided into seroconverted (n=51) and non-seroconverted (n=22) groups were assessed. The presence of specific anti-nucleocapsid (anti-N) IgM and IgG for SARS-CoV-2 was evaluated. IgG antibodies to the SARS-CoV-2 spike receptor-binding domain were used to confirm non-seroconversion in all negative anti-N. Results: Four recurrent cases displayed mild symptoms and were non-seroconverted until the recurrence of symptoms. Conclusions: Undetectable anti-nucleocapsid IgM and IgG levels may be correlated with symptomatic COVID-19 recurrence.