https://www.selleckchem.com/products/sar405.html 1, IQR 17.1-78.4 vs. 29.1, IQR 12.1-54.2 kAU/L, p 0.004). Female gender (OR 1.55, 95% CI 1.05-2.27), a proportional increase in the number of symptoms at the onset of COVID-19 (OR 1.81, 95% CI 1.59-2.05) and ICU admission OR 3.10, 95% CI 1.18-8.11) were all independent risk factors for post-COVID-19 syndrome. The same predictors also emerged in a subgroup of 231 patients with the serological follow-up available at the time of the interview alongside the proportional increase in anti-SARS-CoV-2 IgG (OR 1.01, 95% CI 1.00-1.02, p 0.04). Prospective follow-up could be offered to specific subgroups of COVID-10 patients, to identify typical symptoms and persistently high anti-SARS-CoV-2 IgG titres as a means of early detection of post-COVID-19 long-term sequelae. Prospective follow-up could be offered to specific subgroups of COVID-10 patients, to identify typical symptoms and persistently high anti-SARS-CoV-2 IgG titres as a means of early detection of post-COVID-19 long-term sequelae. Bacteria colonizing the upper respiratory tract (URT) of young children play a key role in the pathogenesis of lower respiratory tract infection (LRTI). To systematically review the literature on the association between bacteria colonizing the URT and LRTI among young children. MEDLINE, Academic Search Premier, Africa-Wide Information and CINAHL, Scopus and Web of Science. Studies published between 1923 and 2020, investigating URT bacteria from LRTI cases and controls. Children under 5years with and without acute LRTI. Three reviewers independently screened titles, abstracts and full texts. Meta-analysis was done using Mantel-Haenszel fixed- or random-effects models. Most eligible studies (41/50) tested nasopharyngeal specimens when investigating URT bacteria. Most studies were of cross-sectional design (44/50). Twenty-four studies were performed in children in lower- or lower-middle-income countries (LMICs). There was higher prevalence of H