The Omicron Sub-Variant BA.4 Displays a Remarkable Lack of Clinical Signs in a Golden Syrian Hamster Model of SARS-CoV-2 Infection.

The ongoing emergence of SARS-CoV-2 virus variants remains a source of concern because it is accompanied by the potential for increased virulence as well as evasion of immunity. Here we show that, although having an almost identical spike gene sequence as another Omicron variant (BA.5.2.1), a BA.4 isolate lacked all the typical disease characteristics of other isolates seen in the Golden Syrian hamster model despite replicating almost as effectively. Animals infected with BA.4 had similar viral shedding profiles to those seen with BA.5.2.1 (up to day 6 post-infection), but they all failed to lose weight or present with any other significant clinical signs. We hypothesize that this lack of detectable signs of disease during infection with BA.4 was due to a small (nine nucleotide) deletion (∆686-694) in the viral genome (ORF1ab) responsible for the production of non-structural protein 1, which resulted in the loss of three amino acids (aa 141-143).

SARS-CoV-2 Disease Severity in the Golden Syrian Hamster Model of Infection Is Related to the Volume of Intranasal Inoculum.

The golden Syrian hamster (Mesocricetus auratus) is now commonly used in preclinical research for the study of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and the assessment of vaccines, drugs and therapeutics. Here, we show that hamsters inoculated via the intranasal route with the same infectious virus dose of prototypical SARS-CoV-2 administered in a different volume present with different clinical signs, weight loss and viral shedding, with a reduced volume resulting in reduced severity of disease similar to that obtained by a 500-fold reduction in the challenge dose. The tissue burden of the virus and the severity of pulmonary pathology were also significantly affected by different challenge inoculum volumes. These findings suggest that a direct comparison between the severity of SARS-CoV-2 variants or studies assessing the efficacy of treatments determined by hamster studies cannot be made unless both the challenge dose and inoculation volume are matched when using the intranasal route. Additionally, analysis of sub-genomic and total genomic RNA PCR data demonstrated no link between sub-genomic and live viral titres and that sub-genomic analyses do not provide any information beyond that provided by more sensitive total genomic PCR.

Syrian hamster convalescence from prototype SARS-CoV-2 confers measurable protection against the attenuated disease caused by the Omicron variant.

The mutation profile of the SARS-CoV-2 Omicron (lineage BA.1) variant posed a concern for naturally acquired and vaccine-induced immunity. We investigated the ability of prior infection with an early SARS-CoV-2 ancestral isolate (Australia/VIC01/2020, VIC01) to protect against disease caused by BA.1. We established that BA.1 infection in naïve Syrian hamsters resulted in a less severe disease than a comparable dose of the ancestral virus, with fewer clinical signs including less weight loss. We present data to show that these clinical observations were almost absent in convalescent hamsters challenged with the same dose of BA.1 50 days after an initial infection with ancestral virus. These data provide evidence that convalescent immunity against ancestral SARS-CoV-2 is protective against BA.1 in the Syrian hamster model of infection. Comparison with published pre-clinical and clinical data supports consistency of the model and its predictive value for the outcome in humans. Further, the ability to detect protection against the less severe disease caused by BA.1 demonstrates continued value of the Syrian hamster model for evaluation of BA.1-specific countermeasures.

Non-traumatic extraocular muscle haemorrhage associated with anticoagulation use.

We present a case of a unilateral extraocular muscle haematoma in an adult female patient who was compliant with life-long oral anticoagulation for recurrent deep vein thrombosis. The patient presented with symptoms of sudden-onset left-sided headache radiating to the temporal region, which started 2 days prior. No obvious triggering factors were identified. Cranial and ocular examinations were within normal limits. Imaging revealed a haemorrhage related to the lateral rectus muscle of the left eye. Conservative management was employed with abstinence from anticoagulation for 2 weeks and a weaning regime of oral steroids. Under the clinical review of ophthalmology and interval radiological monitoring, symptoms were reduced with reduction of haemorrhage size. Anticoagulation was reinstated after 2 weeks. To our knowledge, this is the first case of a non-traumatic extraocular muscle haematoma to be reported in a patient on anticoagulation.

Cancer care during the COVID-19 pandemic: a perspective from Saudi Arabia.

The coronavirus disease 2019 (COVID-19) pandemic continues to disrupt many healthcare settings worldwide including cancer care. COVID-19 has been associated with worse outcomes amongst cancer patients. Saudi Arabia has experienced several Middle East respiratory syndrome coronavirus (MERS-CoV) outbreaks that affected the continuity of cancer care. In this paper, we describe how Saudi Arabia responded to COVID-19, how cancer care was re-restructured during this pandemic and how the recent MERS-CoV experience may have improved the Saudi response to COVID-19.

Additional challenges faced by cancer patients in Gaza due to COVID-19.

Cancer patients in conflict settings experience significant barriers in accessing chemotherapy and radiotherapy as well as palliative care and psychosocial support. Now they face an additional possible risk of infection by SARS-CoV-2 novel coronavirus and the indirect impact of the COVID-19 pandemic on movement restrictions and their access to care. In this commentary, we highlight that despite the low COVID-19 burden in conflict settings like Gaza, COVID-19 could lead to further inequity in cancer care and poorer outcomes for Palestinians with cancer. This is due to the pre-existing shortage in cancer resources as well as the lack of context-specific guidelines to prepare for COVID-19 in war-torn settings.