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The protection against emerging SARS-CoV-2 variants by pre-existing antibodies elicited due to the current vaccination or natural infection is a global concern. We aimed to investigate the rate of SARS-CoV-2 infection and its clinical features among infection-naïve, infected, vaccinated, and post-infection-vaccinated individuals. A cohort was designed among icddr,b staff registered for COVID-19 testing by real-time reverse transcriptase-polymerase chain reaction (rRT-PCR). Reinfection cases were confirmed by whole-genome sequencing. From 19 March 2020 to 31 March 2021, 1644 (mean age, 38.4 years and 57% male) participants were enrolled; where 1080 (65.7%) were tested negative and added to the negative cohort. The positive cohort included 750 positive patients (564 from baseline and 186 from negative cohort follow-up), of whom 27.6% were hospitalized and 2.5% died. Among hospitalized patients, 45.9% had severe to critical disease and 42.5% required oxygen support. Hypertension and diabetes mellitus were found significantly higher among the hospitalised patients compared to out-patients; risk ratio 1.3 and 1.6 respectively. The risk of infection among positive cohort was 80.2% lower than negative cohort (95% CI 72.6–85.7%; p < 0.001). Genome sequences showed that genetically distinct SARS-CoV-2 strains were responsible for reinfections. Naturally infected populations were less likely to be reinfected by SARS-CoV-2 than the infection-naïve and vaccinated individuals. Although, reinfected individuals did not suffer severe disease, a remarkable proportion of naturally infected or vaccinated individuals were (re)-infected by the emerging variants.

ResearchObjective To estimate the validity (sensitivity, specificity, and positive and negative predictive values) of a clinical algorithm as used by community health workers (CHWs) to detect and classify neonatal illness during routine household visits in rural Bangladesh. Methods CHWs evaluated breastfeeding and symptoms and signs of illness in 395 neonates selected randomly from neonatal illness surveillance during household visits on postnatal days 0, 2, 5 and 8. Neonates classified with very severe disease (VSD) were referred to a community-based hospital. Within 12 hours of CHW assessments, physicians independently evaluated all neonates seen in a given day by one CHW, randomly chosen from among 36 project CHWs. Physicians recorded symptoms and signs of illness, classified the illness, and determined whether the newborn needed referral-level care at the hospital. Physicians' identification and classification were used as the gold standard in determining the validity of CHWs' identification of symptoms and signs of illness and its classification. Findings CHWs' classification of VSD showed a sensitivity of 73%, a specificity of 98%, a positive predictive value of 57% and a negative predictive value of 99%. A maternal report of any feeding problem as ascertained by physician questioning was significantly associated (P < 0.001) with "not sucking at all" and "not attached at all" or "not well attached" as determined clinically by CHWs during feeding assessment. Conclusion CHWs identified with high validity the neonates with severe illness needing referral-level care. Home-based illness recognition and management, including referral of neonates with severe illness by CHWs, is a promising strategy for improving neonatal health and survival in low-resource developing country settings.Une traduction en français de ce résumé figure à la fin de l'article. Al final del artículo se facilita una traducción al español.

bGiven the increases in drug-resistant tuberculosis, laboratory capacities for drug susceptibility testing are being scaled up worldwide. A laboratory must decide among several endorsed methodologies. We evaluated 87 Mycobacterium tuberculosis isolates for concordance of susceptibility results across six methods: the L-J proportion method, MGIT 960 SIRE AST, Gene/Xpert MTB/ RIF, GenoType MTBDRplus line probe assay, MycoTB MIC plate, and a laboratory-developed mycobacteriophage quantitative PCR (qPCR)-based method. Most (80%) isolates were multidrug resistant. Of the culture-based methods, the mycobacteriophage qPCR method was fastest, the L-J proportion method was the slowest, and the MGIT method required the most repeat testing (P < 0.05). For isoniazid (INH), 82% of isolates were susceptible by all methods or resistant by all methods, whereas for rifampin (RIF), ethambutol (EMB), and streptomycin (STR), such complete concordance was observed in 77%, 50%, and 51% of isolates, respectively (P < 0. G iven the increasing rates of multidrug-resistant tuberculosis (MDR-TB) isolates worldwide and the emergence of extensively drug-resistant TB, the development of rapid and accurate methods for drug susceptibility testing (DST) of Mycobacterium tuberculosis isolates is a global priority. The culture-based proportion method that employs Löwenstein-Jensen medium is a World Health Organization (WHO)-recommended method that has been in wide use for over 50 years (1, 2). Such solid medium-based DST methods are slow, requiring readings at 4 to 6 weeks, which delays the detection of drug resistance and risks inappropriate treatment and spread of drug-resistant strains. This deficiency has led to the development of newer DST methodologies, including liquid culture systems and molecular line probe assays, which have also received recommendations from WHO (3, 4).As a consequence, laboratories have seen an accumulation of methods from which they must choose, and a given specimen or isolate may be tested across a variety of methods. A natural consequence is that discrepancies between methods may be encountered. Such discrepancies may be of little consequence in certain scenarios, such as streptomycin (STR) resistance in settings that use primarily isoniazid (INH), rifampin (RIF), pyrazinamide (PZA), and ethambutol (EMB), but they may have critical implications for treating MDR-TB in areas where the arsenal of drugs is limited in number and potency. Discordance is becoming a vexing aspect for TB clinicians and will likely increase in frequency as new methodologies are adopted, yet its extent has received little attention. Most diagnostic evaluations examine one new method against one gold standard reference method, not several methods against each other. Additionally, most diagnostic evaluations are performed on predominantly drug-susceptible isolates, often highly susceptible clinical isolates or reference strains, and thus discrepancies between methods would be expected to be rare.For this reason, we prospectively examined 87 mos...

Rotavirus-specific subclass antibody responses and cytokines, tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukin-8 (IL-8), and IL-10, were measured in children 7-24 months of age with rotavirus diarrhoea (n = 29); the responses were compared with children with watery diarrhoea from whom no enteric pathogens were isolated (controls; n = 11). All children had diarrhoea for < 5 days and were enrolled from the Dhaka Hospital of the Centre for Health and Population Research. Samples of blood and stools were collected on the day of enrollment and 18-21 days after the onset of diarrhoea. Children showing a > or = 4-fold rise in antibody titre between the acute and convalescent stages were considered to have a response. The numbers of children with rotavirus-specific IgA and IgA1 responses in stool were similar in the two groups of children. In the plasma, more children with rotavirus diarrhoea had rotavirus-specific IgA, IgA1, IgG, IgG1, and IgG3 responses than did control children (P = 0.049, 0.007, 0.001, 0.002, and 0.012, respectively). IgA2 was not detectable. Among cytokines measured in supernatants from peripheral blood mononuclear cells (PBMCs) cultured for 6 and 24 hr, IFN-gamma was the only cytokine that was higher in children with rotavirus diarrhoea compared with controls (P = 0.013). Severity of illness did not correlate with nutritional status or antibody titres, but severity did correlate with TNF-alpha during the acute stage of illness. IFN-gamma correlated positively with IgG1 titres. These findings suggest a role for IFN-gamma in the pathogenesis of rotavirus infection, but this needs confirmation by other studies. The immune responses described are relevant to future vaccine trials, as immune responses in vaccinees should mimic those in natural infection.