Kinetics of Covid-19 antibodies in terms of titre and duration among healthcare workers: A longitudinal study

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.

Seroprevalence of COVID-19 Amongst Health Care Workers in a Tertiary Care Hospital of a Metropolitan City from India

BACKGROUND

Seroprevalence studies for COVID-19 evaluate the extent of undetected transmission in a defined community, with special significance among health care workers (HCW) owing to their greater exposure and potential to transmit.

METHODS

A total of 1122 HCW (approximately 25% of the employees) of a large tertiary care hospital in India were recruited for this cross-sectional study. COVID PCR-positive HCW were excluded. Based on their risk-assessment, participants were grouped into three categories. A questionnaire was administered and they were tested for SARS-CoV-2-IgG antibodies using the chemiluminescence.

RESULTS

The overall seroprevalence among workers was 11.94%, which included 19.85% in COVID units, 11.09% in non-COVID units, and 8% in administrative workers (p=0.007). Antibody prevalence was highest in the department of gastroenterology (11.94%), followed by oncology (10.53%), pathology (10.26%), emergency medicine (7.84%) and critical care medicine (7%). Housekeeping staff, food and beverage staff, lab assistants and technicians had higher seroprevalence rate than doctors and nurses (p < 0.0001). HCW with a history of BCG vaccination in childhood and those who received an adequate prophylactic dose of hydroxychloroquine (HCQ) had a lower seroprevalence as compared to those who did not (7.31% vs. 16.8% and 1.30% vs. 11.25% respectively).

CONCLUSION

BCG vaccination, HCQ prophylaxis, and the job profile influence the seroprevalence rate in HCW. Seroprevalence rate and follow-up evaluation of its durability may help hospitals to triage their staff at risk, rationalize their placement, prioritize the use of PPE, thereby potentially reducing the risk.

Thyrotoxic Channelopathies

Thyrotoxic periodic paralysis (TPP), a disorder most commonly seen in Asian men, is characterized by abrupt onset of hypokalemia and paralysis. The condition primarily affects the lower extremities and is secondary to thyrotoxicosis. Early recognition of TPP is vital to initiating appropriate treatment and to avoiding the risk of rebound hyperkalemia that may occur if high-dose potassium replacement is given. Here we present a case of 31 year old male with thyrotoxic periodic paralysis with diagnostic and therapeutic approach.

Magnetic orotracheal intubation: a new technique

We sought to determine the effectiveness of a magnet placed over the thyroid cartilage in the neck to guide an endotracheal tube into the trachea. Forty patients aged 18 to 60 yr with normal airway anatomy (ASA grade I) who required general anesthesia with an endotracheal tube and paralysis for their surgery were chosen and informed consents were obtained. The tip of the epiglottis was exposed with a No. 3 MacIntosh laryngoscope, and a magnet was held over the thyroid cartilage. A catheter with stylet was placed behind the epiglottis allowing the magnet to pull the stylet and catheter close to the glottic opening. The catheter was advanced into the trachea over the stylet and its position was confirmed by auscultating the lungs and by capnography. An extension tube was connected to the catheter, and the endotracheal tube was guided into the trachea over the catheter. The tracheas of 37 patients were intubated on the first attempt with the magnet. The tracheas of the remaining three patients could not be intubated on the first attempt but were successfully intubated without complications on the second attempt. An additional five patients with an anterior larynx whose tracheas could not be intubated with direct laryngoscopy also had tracheal intubation with a magnet. This magnet-guided technique can be used when it is difficult to expose a patient's larynx. It is noninvasive, simple, and can be used without any delay when expensive flexible fiberoptic endoscopes are not readily available. The procedure takes an average of 1 to 2 min.