Clinical risk factors for predicting anti-Sars-CoV-2 antibody immunoreactivity duration after mild COVID-19 infection

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.Alternate abstract: 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 Transcription–Polymerase 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.

Ultra-rapid on-site detection of SARS-CoV-2 infection using simple ATR-FTIR spectroscopy and analysis algorithm: high sensitivity and specificity (preprint)

There is an urgent need for ultra-rapid testing regimens to detect the SARS-CoV-2 [Severe Acute Respiratory Syndrome Coronavirus 2] virus infections in real-time within seconds to stop its spread. Current testing approaches for this RNA virus focus primarily on diagnosis by RT-qPCR, which is time-consuming, costly, often inaccurate and impractical for general population rollout due to the need for laboratory processing. The latency until the test result arrives with the patient has led to further virus spread. Furthermore, latest antigen rapid tests still require 15 to 30 min processing time and are challenging to handle. Despite increased PCR-test and antigen-test efforts the pandemic has entered the worldwide second stage. Herein, we applied a superfast reagent-free and non-destructive approach of attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy with subsequent chemometric analysis to the interrogation of virus-infected samples. Contrived samples with inactivated gamma-irradiated Covid-19 virus particles at levels down to 1582 copies/ml generated infrared (IR) spectra with good signal-to-noise ratio. Predominant virus spectral peaks are associated with nucleic acid bands, including RNA. At low copy numbers, the presence of virus particle was found to be capable of modifying the IR spectral signature of saliva, again with discriminating wavenumbers primarily associated with RNA. Discrimination was also achievable following ATR-FTIR spectral analysis of swabs immersed in saliva variously spiked with virus. Following on, we nested our test system in a clinical setting wherein participants were recruited to provide demographic details, symptoms, parallel RT-qPCR testing and the acquisition of pharyngeal swabs for ATR-FTIR spectral analysis. Initial categorisation of swab samples into negative versus positive Covid-19 infection was based on symptoms and PCR results. Following training and validation of a genetic algorithm-linear discriminant analysis (GA-LDA) algorithm, a blind sensitivity of 95% and specificity of 89% was achieved. This prompt approach generates results within two minutes and is applicable in areas with increased people traffic that require sudden test results such as airports, events or gate controls.