ABSTRACT
BACKGROUND Most individuals with Covid-19 infection develop antibodies specific to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, the dynamics of these antibodies is variable and not well-studied. We aimed to determine the titres of naturally acquired antibodies over a 12-week follow-up. METHODS We recruited healthcare workers who had tested positive on a specific quantitative reverse transcription-polymerase chain reaction (qRT-PCR) for SARS-CoV-2, and then tested for the presence of immunoglobulin G (IgG) antibody against the same virus at baseline and again at 6 and 12 weeks. The antibody titre was determined by a semi-quantitative assay based on signal/cut-off ratio. Healthcare workers with antibody positivity were divided into those with high titre (ratio ?12) and low titre (<12). Their demographic details and risk factors were surveyed through a Google form and analysed in relation to the antibody titres at three time-points. RESULTS Of the 286 healthcare workers, 10.48% had high antibody titres. Healthcare workers who had tested positive by qRT-PCR and those who had received the Bacille Calmette–Guérin (BCG) vaccination or other immune-boosters had a higher frequency of high antibody titres. While there was a significant decline in antibody titres at 6 and 12 weeks, 87.46% of individuals positive for IgG antibody persisted to have the antibody even at 12 weeks. CONCLUSION Healthcare workers who tested positive for SARS-CoV-2 on qRT-PCR had a high positivity for the specific antibody, which continued to express in them even at 12 weeks. Further follow-up is likely to enhance our understanding of antibody kinetics following SARS-CoV-2 infection.
ABSTRACT
Background: Aim of current study was to determine the clinical characteristics, radiological, laboratory features and anti-tubercular drug sensitivity in new smear positive (category I) pulmonary tuberculosis cases in a tertiary care dedicated TB OPD, Delhi. Methods: The study was a cross-sectional observational study and consists of 100 cases of new smear positive pulmonary tuberculosis cases (category I) irrespective of age and sex. The sputum were collected, stained with Ziehl-Nielsen (Z-N) staining and ultimately inoculated on Lowenstein-Jensen (L-J) media for six weeks. All sputum smear positive cases were subjected to culture and drug-susceptibility testing by 1% proportion method on Lowenstein-Jensen (LJ) medium. The Drug-Susceptibility Testing (DST) for isoniazid (INH), rifampicin (R-cin), ethambutol (EMB) and streptomycin (SM) were performed. Results: The age & sex distribution of 100 patients showed that majority of the patients (79%) belonged to 2nd, 3rd and 4th decades & 60 % were males and 40% were female with male to female ratio 3:2 respectively. Cough (83%), fever (77%) and weight loss (76%) were the most common presenting clinical features. The chest X-ray of 100 smear positive patients showed that 53% of patients had evidence of 35% unilateral and 18% bilateral consolidation and 46% had cavitary lesions on chest X-ray (PA view) with 37% and 9% of patients having unilateral and bilateral cavities respectively. Of these 82 culture positives, 56.1% (n=46) were susceptible to all first-line anti-tubercular drugs, while 43.9% (n=36) were resistant to mostly one or other anti-tubercular drugs (INH, R-cin, SM or EMB). Conclusion: We stressed the importance of early diagnosis of new cases by clinico-pathological features, identifying of drug resistance trends in anti-tubercular treatment naïve patients, in order to assess the efficacy of current interventions. Overall, these findings emphasize the importance of early diagnosis of drug resistance pattern of M. tuberculosis isolates to anti-tubercular in category I patients as well as its association with HIV across the country to timely modify and strengthen the national programs in order to prevent the emergence of MDR-TB strains and avert the threat of XDR-TB.