A ‘thrombosis’ is the medical term for a blood clot. Blood clots can occur within the arterial and venous supplies of our body, but when they occur in the vasculature supplying the brain, they lead to a deadly and potentially permanently disabling condition called ‘ischaemic stroke’. The entire world has come to terms with the emerging and severe health complications imposed by the SARS-CoV-2 virus causing the COVID-19 pandemic, and there is no doubt that the deadly disease also has a connection with stroke.
Reports from early days since the onset of the pandemic show that the virus has been associated with increased rates of both arterial and venous thrombosis in the pulmonary and systemic circulation. The pathological explanation behind this is the activation of the innate immune system which occurs in response to the entry of a viral pathogen into the body. This in turn activates several pathways in our body which are responsible for coagulation or ‘clotting’ of blood to occur, ultimately leading to thrombosis.
Scientific studies from Wuhan, China, have also described poorer outcomes among those already with a history of stroke, among infected patients and increased rates of in-hospital mortality. Another study by Yaghi et al., in the USA which was one of the first ones to examine the rates of stroke among Covid-infected patients found that 0.9% of the total number of hospitalised patients had experienced an ischemic stroke, with cryptogenic stroke (patients with no typical cause of a stroke) also occurring twice as frequently in positive patients. Also reported were incidents of large-vessel strokes in young patients (50< years), from New York City.
In a very interesting study led by Qureshi and colleagues, from earlier this year, a large cohort of 27,676 Covid-positive patients from 54 healthcare facilities were analysed using a dataset. The dataset contained patient data from those that had encountered either an emergency department or inpatient admission.
The team found an increased incidence of ischemic stroke among older people, ethnically belonging to an African American background, with a history of co-morbidities such as hypertension, diabetes mellitus, atrial fibrillation and congestive heart failure – to name a few. Post-discharge destination to anywhere other than home was found to have increased the likelihood of stroke occurrence by twice.
Undoubtedly, with existing barriers to stroke care under regular circumstances, the pandemic further heightened the extent of problems associated with post-stroke healthcare services. A survey which collected data from 13 tertiary care hospitals in India, found that stroke rehabilitation services, especially for outpatient care were impacted in more than 53% of the total number due to staff, personnel shortages and poor access.
However, evidence has shown that timely intervention, despite the risk associated with COVID-19 infection, can help reduce the burden of the disease in low-resource settings. In Nepal, out of all the patients presenting to the hospital between March and July 2020, 85 were diagnosed with ischaemic stroke and 10 cases of hyper-acute stroke were managed within the safe – window period suitable for thrombolysis. Patients were immediately undertaken for imaging, routine blood investigation protocols were initiated simultaneously and were administered with the required treatment modalities (within 25-30 minutes).
The link between COVID-vaccines and possible stroke – emerging evidence:
Reports of coagulopathy have appeared following COVID-19 vaccination particularly with the ChAdOx1 nCoV-19 vaccine by AstraZeneca. In one series of 23 patients, 13 had cerebral venous thrombosis and 5 were found to have pulmonary emboli. The median time of the adverse event following immunisation (AEFI) was after 12 days. Al-Mahyani et al, also described three cases of ischaemic stroke following COVID-19 vaccination, found to be associated with large artery occlusion. These events, collectively impacting the vasculature of the brain, can be referred to as “vaccine-induced immune thrombotic thrombocytopaenia” or VITT.
Despite adverse complications, it is imperative to remember that vaccination is extremely imperative to prevent the further spread of COVID-19. Professor Hugh Markus of the University of Cambridge mentions “ it is important to remember that these side-effects are rare, and much less common than both cerebral venous thrombosis and ischaemic stroke associated with COVID-19 infection itself”.
Note of caution: The author, Stuti, does not intend to persuade any individual against the administration of vaccines preventing COVID-19. All of the information presented above is derived from scientifically published, peer-reviewed reports of adverse events associated with various vaccines available, and have extremely rare occurrences. The author supports vaccination and urges everyone reading this, to mobilise efforts to get vaccinated at the earliest, in order to protect oneself from contracting COVID-19.