With the continuous emergence of SARS-CoV-2 variants of concern and implementation of mass-scale interventions like vaccination, understanding factors affecting disease transmission has critical implications for control efforts. Here we used a simple adapted N95 mask sampling method to demonstrate the impact of circulating SARS-CoV-2 variants and vaccination on 92 COVID-19 patients to expel virus into the air translating to a transmission risk. Between July and September 2021, when the Delta was the dominant circulating strain in Mumbai, we noted a two-fold increase in the proportion of people expelling virus (95%), about an eighty-fold increase in median viral load and a three-fold increase in high emitter type (41%; people expelling >1000 viral copy numbers in 30 minutes) compared to initial strains of 2020. Eight percent of these patients continued to be high emitters even after eight days of symptom onset, suggesting a probable increased transmission risk for Delta strain even at this stage. There was no significant difference in expelling pattern between partial, full and un-vaccinated individuals suggesting similar transmission risk. We noted significantly more infections among vaccinated study patients and their household members than unvaccinated, probably due to increased duration from vaccination and/or increased risk behaviour upon vaccination due to lower perceived threat. This study provides biological evidence for possible continued transmission of the Delta strain even with vaccination, emphasizing the need to continue COVID-19 appropriate behaviour. The study also indicates that the mask method may be useful for screening future vaccine candidates, therapeutics or interventions for their ability to block transmission.
The present study was initiated to understand the proportion of predominant variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in postvaccination infections during the Delta dominated second wave of coronavirus disease 2019 (COVID-19) in the Mumbai Metropolitan Region (MMR) in India and to understand any mutations selected in the postvaccination infections or showing association with any patient demographics. Samples were collected (n = 166) from severe/moderate/mild COVID-19 patients who were either vaccinated (COVISHIELD/COVAXIN-partial/fully vaccinated) or unvaccinated, from a city hospital and from home isolation patients in MMR. A total of 150 viral genomes were sequenced by Oxford Nanopore sequencing and the data of 136 viral genomes were analyzed for clade/lineage and for identifying mutations. The sequences belonged to three clades (21A, 21I, and 21J) and their lineage was identified as either Delta (B.1.617.2) or Delta+ (B.1.617.2 + K417N) or sub-lineages of Delta variant (AY.120/AY.38/AY.99). A total of 620 mutations were identified of which 10 mutations showed an increase in trend with time (May-October 2021). Associations of six mutations (two in spike, three in orf1a, and one in nucleocapsid) were shown with milder forms of the disease and one mutation (in orf1a) with partial vaccination status. The results indicate a trend toward reduction in disease severity as the wave progressed.
Background: Bioaerosols from pulmonary tuberculosis (PTB) patients are a quantitative predictor of transmission. Current methods involve sophisticated instruments and time-consuming techniques to assess viable TB bacteria in bioaerosols. We tested the feasibility of detecting Mycobacterium tuberculosis (Mtb) specific RNA from bioaerosols retained on TB patients' masks. Methods: Adult PTB patients (n = 33) were recruited at diagnosis before GeneXpert confirmation between April-2017 to February-2019 from private TB clinics in Mumbai. Face mask worn for 1 or 3 h or N95 mask containing a cellulose acetate membrane worn for 5 min by the patients were tested for the presence of Mtb RNA by quantitative PCR and bacterial load was estimated. Results: Quantitative PCR targeting rpoB, sigA,16S and fgd1 and sequencing of rpoB confirmed the presence of Mtb specific RNA in mask samples including masks of two patients with unproductive sputum. Membrane samples had seven-fold higher RNA and bacterial load that correlated to bacterial load estimated by sputum GeneXpert. Conclusion:The study demonstrates that patient masks can be used to sample bioaerosols for detection of viable Mtb. The findings have translational value in the diagnosis of TB and monitoring Mtb variations between and within patients useful for assessing infectiousness and treatment response.
We report here the genome sequences of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants from five coronavirus disease 2019 (COVID-19) patients in Mumbai, India. Viral genomic RNA was isolated from nasopharyngeal swabs and/or respiratory particles from the masks of the patients. Genomic variant analysis determined 8 to 22 mutations, and the variants belong to lineages previously associated with Indian variants.
Effective treatment reduces a tuberculosis patient's ability to infect others even before they test negative in sputum or culture. Currently, the basis of reduced infectiousness of the Mycobacterium tuberculosis (Mtb) with effective treatment is unclear. We evaluated changes in aerosolized bacteria expelled by patients through a transcriptomic approach before and after treatment initiation (up to 14 days) by RNA sequencing. A distinct change in the overall transcriptional profile was seen post-treatment initiation compared to pretreatment, only when patients received effective treatment. This also led to the downregulation of genes associated with cellular activities, cell wall assembly, virulence factors indicating loss of pathogenicity, and a diminished ability to infect and survive in new host cells. Based on this, we identified genes whose expression levels changed with effective treatment. The observations of the study open up avenues for further evaluating the changes in bacterial gene expression during the early phase of treatment as biomarkers for monitoring response to tuberculosis treatment regimens and provide means of identifying better correlates of Mtb transmission.
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