Assessment of Risk Factors for COVID-19 in Health Care Workers: A Nested Case-Control Study

OBJECTIVES

To study the risk factors for SARS-CoV-2 infection in health care workers (HCWs) exposed to COVID-19 patients.

MATERIAL AND METHODS

This was a nested case-control study of health care workers(HCWs) in a Dedicated COVID Hospital(DCH). The data collection was done from Dec 2020 to Feb 2021. The study was part of an international multicenter study by the World Health Organisation (WHO).2 The Doctors, nurses, housekeeping staff, clerks, and other staff working in this DCH were considered as HCWs. HCWs working in this DCH with confirmed COVID-19 were recruited as cases and other HCWs working in this DCH in the same Ward/ICU/office without infection were recruited as controls (incidence density sampling). Three controls were taken per case. The questions were in the Likert scale.

RESULTS

There were 25 cases and their 75 controls. There was no significant difference between cases and controls with respect to age, sex, occupation, education, and comorbidities and all controls were negative for antibodies at the time of the interview. Most (70%) of the HCWs were doctor by profession followed by nurses (19%). All HCWs were trained in IPC (infection Prevention and Control). Most (96%) HCWs reported that PPE (personal protective equipment) is available in sufficient quantity. There was no significant difference between cases and controls with respect to those having direct contact with the patient's materials, surroundings, and following hand hygiene.

CONCLUSION

Adequate availability of PPE, IPC training of HCWs are important for preventing COVID-19 but do not completely reduce risk among HCWs.

Bilateral vestibular schwannomas in older patients: NF2 or chance?

BACKGROUND

Neurofibromatosis type 2 (NF2) is an autosomal dominant condition with high spontaneous mutation rate which predisposes to the development of multiple nerve sheath tumours (schwannomas), meningiomas and ependymoma. The cardinal feature and main diagnostic criterion for the diagnosis of NF2 remains the development of bilateral vestibular schwannoma (BVS). With increasing use of MRI screening the possibility of a 'chance' diagnosis of BVS has been mooted with a potential frequency of one in two million people in their lifetime. Until now, however, no evidence for such an event has been published. We aimed to demonstrate that chance occurrence can occur and to estimate its frequency among those with just BVS late in life.

METHODS

Two vestibular schwannomas from the same patient were DNA sequenced and underwent loss of heterozygosity analysis.

RESULTS

We show that a man who developed BVS, at ages 52 and 67 years developed these tumours sporadically by demonstrating that there were no molecular events in common between the two tumours. Furthermore from a database of over 1200 patients with NF2, we have estimated that ~25% of cases of BVS over 50 years and 50% over 70 years of age where no other features of NF2 are present represent a chance occurrence rather than due to an underlying mosaic or constitutional NF2 mutation.

CONCLUSIONS

Patients presenting with BVS later in life should be appraised of the potential likelihood they may not have NF2 and the resultant further reduction in risks of transmission to offspring.

Mosaicism in neurofibromatosis type 2: an update of risk based on uni/bilaterality of vestibular schwannoma at presentation and sensitive mutation analysis including multiple ligation-dependent probe amplification

BACKGROUND

Neurofibromatosis type 2 (NF2) is almost unique among inherited disorders in the frequency of mosaicism in the first affected generation. However, the implications of this on transmission risks have not been fully elucidated.

METHODS

The expanded database of 460 families with NF2 and 704 affected individuals was analysed for mosaicism and transmission risks to offspring.

RESULTS

64 mosaic patients, with a projected mosaicism rate of 33% for sporadic classical NF2 with bilateral vestibular schwannoma at presentation and 60% for those presenting unilaterally, were identified. Offspring risks can be radically reduced on the basis of a sensitive mutation analysis of blood DNA including multiple ligation-dependent probe amplification (MLPA, which detects 15% of all mutations), but even MLPA cannot detect high levels of mosaicism.

CONCLUSION

The chances of mosaicism in NF2 and the resultant risks of transmission of the mutation to offspring in a number of different clinical situations have been further delineated. The use of MLPA in this large NF2 series is also reported for the first time.

Should NF2 mutation screening be undertaken in patients with an apparently isolated vestibular schwannoma?

Early onset of vestibular schwannoma (VS) is associated with the inherited condition neurofibromatosis type 2 (NF2). However, the majority of NF2 presents bilaterally and the proportion of early-onset apparent sporadic unilateral VS because of NF2 remains to be determined. We have determined the risk by studying NF2 risk in a population-based set of VS, looking at the mode of presentation in a large NF2 data set and the outcome of NF2 mutation analysis in 148 sporadic unilateral VS. The risk of NF2 in an apparently sporadic case of unilateral VS is small apart from in the very youngest age group (<20 years). NF2 germ line mutation testing is unlikely to reveal a mutation except <20 years as a result of the low risk and high rates of mosaicism. Germ line mutation testing is probably only justified in sporadic unilateral VS <20 years unless other features of NF2 are present. Ideally mutation testing should start with the original tumour specimen.