Kinetics of humoral immune response over 17 months of COVID-19 pandemic in a large cohort of healthcare workers in Spain: The ProHEpiC-19 study (preprint)

BackgroundUnderstanding the immune response to the SARS-CoV-2 virus is critical for efficient monitoring and defence strategies. The ProHEpic-19 cohort provides a fine-grained description of the kinetics of antibodies after SARS-CoV-2 infection with an exceptional resolution over 17 months.MethodsWe established a cohort of 769 health professionals including healthy and infected with SARS-CoV-2 in northern Barcelona to determine the kinetics of the IgM against the nucleocapsid (N) and the IgG against the N and spike (S) of SARS-CoV-2. We used non-linear mixed models to investigate the kinetics of IgG and IgM measured at nine time points over 17 months from the diagnosis. The model included factors of time, gender, and disease severity (asymptomatic, mild-moderate, severe-critical) to assess their effects and their interactions.Findings: 474 of the 769 participants (61.6%) became infected with SARS-CoV-2. Significant effects of gender and disease severity were found for the levels of all three antibodies. Median IgM(N) levels were already below the positivity threshold in patients with asymptomatic and mild-moderate disease at day 270 after the diagnosis, while IgG(N and S) levels remained positive at least until days 450 and 270, respectively. Kinetic modelling showed a general rise in both IgM(N) and IgG(N) levels up to day 30, followed by a decay with a rate depending on disease severity. IgG(S) levels remained relatively constant from day 15 over time.Interpretation: IgM(N) and IgG(N, S) SARS-CoV-2 antibodies showed a heterogeneous kinetics over the 13 months. Only the IgG(S) showed a stable increase, and the levels and the kinetics of antibodies varied according to disease severity. The kinetics of IgM and IgG observed over a year also varied by clinical spectrum can be very useful for public health policies around vaccination criteria in adult population.Funding: Regional Ministry of Health of the Generalitat de Catalunya (Call COVID19-PoC SLT16_04; NCT04885478) 

Antibody kinetics to SARS-CoV-2 at 13.5 months, by disease severity (preprint)

BackgroundUnderstanding humoral responses and seroprevalence in SARS-CoV-2 infection is essential for guiding vaccination strategies in both infected and uninfected individuals. MethodsWe determine the kinetics of IgM against the nucleocapsid (N) and IgG against the spike (S) and N proteins of SARS-CoV-2 in a cohort of 860 health professionals (healthy and infected) in northern Barcelona. We model the kinetics of IgG and IgM at nine time points over 13.5 months from infection, using non-linear mixed models by sex and clinical disease severity. ResultsOf the 781 participants who were followed up, 478 (61.2%) became infected with SARS-CoV-2. Significant differences were found for the three antibodies by disease severity and sex. At day 270 after diagnosis, median IgM(N) levels were already below the positivity threshold in patients with asymptomatic and mild-moderate disease, while IgG(N, S) levels remained positive to days 360 and 270, respectively. Kinetic modelling showed a general rise in both IgM(N) and IgG(N) levels up to day 30, followed by a decay whose rate depended on disease severity. IgG(S) levels increased at day 15 and remained relatively constant over time. ConclusionsWe describe kinetic models of IgM(N) and IgG(N, S) SARS-CoV-2 antibodies at 13.5 months from infection and disease spectrum. Our analyses delineate differences in the kinetics of IgM and IgG over a year and differences in the levels of IgM and IgG as early as 15 days from symptoms onset in severe cases. These results can inform public health policies around vaccination criteria. Funded by the regional Ministry of Health of the Generalitat de Catalunya (Call COVID19-PoC SLT16_04; NCT04885478)

A Differential Therapeutic Consideration for use of Corticosteroids According to Established COVID-19 Clinical Phenotypes in Critically Ill Patients (preprint)

Background: The steroids are currently used as standard treatment for severe COVID-19. However, the evidence is weak. Our aim is to determine if the use of corticosteroids was associated with Intensive Care Unit (ICU) mortality among whole population and pre-specified clinical phenotypes.Methods: A secondary analysis derived from multicenter, observational study of adult critically ill patients with confirmed COVID-19 disease admitted to 63 ICUs in Spain. Three phenotypes were derived by non-supervised clustering analysis from whole population and classified as (A: severe, B: critical and C: life-threatening). The primary outcome was ICU mortality. We performed a Multivariate analysis after propensity score full matching (PS), Cox proportional hazards (CPH), Cox covariate time interaction (TIR), Weighted Cox Regression (WCR) and Fine-Gray analysis(sHR) to assess the impact of corticosteroids on ICU mortality according to the whole population and distinctive patient clinical phenotypes. Results:  A total of 2,017 patients were analyzed, 1171(58%) with corticosteroids. After PS, corticosteroids were shown not to be associated with ICU mortality (OR:1.0,95%CI:0.98-1.15). Corticosteroids were administered in 298/537(55.5%) patients of “A” phenotype and their use was not associated with ICU mortality (HR=0.85[0.55-1.33]). A total of 338/623(54.2%) patients in “B” phenotype received corticosteroids. The CPH (HR =0.65 [0.46-0.91]) and TIR regression (1- 25 day tHR=0.56[0.39-0.82] and >25 days tHR=1.53[1.03-7.12]) showed a biphasic effect of corticosteroids due to proportional assumption violation. No effect of corticosteroids on ICU mortality was observed when WCR was performed (wHR=0.72[0.49-1.05]). Finally, 535/857(62.4%) patients in “C” phenotype received corticosteroids. The CPH (HR=0.73[0.63-0.98]) and TIR regression (1- 25 day tHR=0.69[ 0.53-0.89] and >25 days tHR=1.30[ 1.14-3.25]) showed a biphasic effect of corticosteroids and proportional assumption violation. However, wHR (0.75[0.58-0.98]) and sHR (0.79[0.63-0.98]) suggest a protective effect of corticosteroids on ICU mortality.     Conclusion: Our finding warns against the widespread use of corticosteroids in all critically ill patients with COVID-19 at moderate-high dose. Only patients with the highest severity could benefit from steroid treatment although this effect on clinical outcome was minimized during ICU stay. 

Bronchoscopy in critically ill COVID-19 Patients: microbiological profile and factors related to nosocomial respiratory infection (preprint)

Background: Nosocomial co-infections are a cause of morbidity and mortality in Intensive Care Units (ICU). Objectives: Our aim was to describe bronchoscopy findings and analyse co-infection through bronchial aspirate (BA) samples in patients with COVID-19 pneumonia requiring ICU admission. Methods: We conducted a retrospective observational study, analysing the BA samples collected from intubated patients with COVID-19 to diagnose nosocomial respiratory infection. Results: One-hundred and fifty-five consecutive BA samples were collected from 75 patients. Of them, 90 (58%) were positive cultures for different microorganisms, 11 (7.1%) were polymicrobial, and 37 (23.7%) contained resistant microorganisms. There was a statistically significant association between increased days of orotracheal intubation (OTI) and positive BA (18.9 days versus 10.9 days, p<0.01), polymicrobial infection (22.11 versus 13.54, p<0.01) and isolation of resistant microorganisms (18.88 versus 10.94, p<0.01). In 88% of the cases a change in antibiotic treatment was made. Conclusion: Nosocomial respiratory infection in intubated COVID-19 patients seems to be higher than in non-epidemic periods. The longer the intubation period, the greater the probability of co-infection, isolation of resistant microorganisms and polymicrobial infection. Microbiological sampling through BA is an essential tool to manage these patients appropriately