Shaded areas represent confidence intervals around LOESS curves After dividing patients according to the severity of disease, peak antibody response appeared to be similar among the two groups. the Holm procedure. Statistical significance was considered as an alpha level of 0,05, two-sided. It should be noted that this is usually a descriptive study; thus, calculated values are only provided to identify most pronounced differences and are not meant to quantify the risk of alpha error on hypothesis testing. LOESS curves were added to scatterplots to facilitate visual identification of trends [29]. Data collection was performed using Microsoft Excel for Office 365 (Microsoft Corporation, Redmond, WA, USA). Statistical analysis and plot design were performed with the R statistical language version 4.0.2 [30] via the RStudio IDE (RStudio, PBC, Boston, MA, USA) [31], using the Tidyverse package [32]. Results Patient populace and serological samples Initially, 198 patients with suspected SARS-COV-2 contamination were considered for inclusion. Of those, 30 were excluded because they did not have a microbiological confirmation of SARS-CoV-2 contamination; Among 168 patients with confirmed contamination, 37 patients were excluded because the onset of symptoms could not be clearly identified. Overall, serological samples included in the analysis were obtained from 131 patients (see Table ?Table1).1). 55 patients had multiple samples drawn during their hospital stay. The median age of our patients was 64?years (IQR 51.5C75) (Table ?(Table1).1). 34 patients developed a severe form of the disease (26%), while 97 were classified as using a moderate form (74%). The median time between symptoms onset and sample collection was 23?days (IQR 12C45, range 1C88). Table 1 Descriptive characteristics of the patients enrolled in the study value are calculated for comparison between each time frame and the Lumefantrine subsequent one There were 18 samples drawn in the first 5?days from the onset of symptoms. Of those, 3 tested positive for IgA (point estimate: Lumefantrine 16.7%, 95% CI 4.4C42.3%). Similarly, there were 18 samples drawn between day 6 and day 10, and of those only 3 tested positive for IgA (16.7%, 95% CI 4.4C42.3%). Conversely, there were 17 samples drawn between day 11 and day 15 and, of those, 12 tested positive for IgA (70.6%, 95% CI 44.0C88.6%). The point estimate for the proportion of positive samples remained stable over 80% from INHBB day 21 onward. There were 26 samples drawn beyond 60?days after the onset of symptoms, all of which tested positive for IgA (100%, 95% CI 82.2C100%). The highest increase in rate of proportion of positive samples was observed between the second and the third time frame, that is between the 6C10-day samples and the 11C15-day samples. Difference between each time frame and the subsequent one showed a peak for samples drawn between days 11 and 15, suggesting that IgA response develop in the majority of patients between days 6?and 15 since the beginning of symptoms (Fig.?1). Open in a separate windows Fig. 1 Positivity rates shows a more abrupt increase Lumefantrine for IgA at the 11C15 time frame, while there is a more smoldered pattern for IgG. Each bar represents the difference in positivity rates between each time frame and the previous?one Positive rate per time frame: IgG The rate of positive samples for IgG divided per time frame are given in Table 2. There were 18 samples drawn in the first 5?days since the onset of symptoms. Of those, 2 tested positive for IgG (11.1%, 95% CI 1.9C36.1%). A similar result applies to the samples drawn between days 6 and 10. A first increase for the rate of positive samples was observed for the samples drawn between 11 and 15?days from the onset of symptoms. At this time frame, there were 18 samples and of those, 6 tested positive for IgG (33.3%, 95% CI 14.4C58.8%). A second increase in the rate of positive samples was observed for samples drawn between 16 and 20?days. At this time frame, there were 17 samples and, of these, 13 tested positive for IgG (76.5%, 95% CI 49.8C92.2%). Of note, the difference between positive rates.