The relationship between COVID-19 and stroke

COVID-19 is a contagious respiratory disease caused by the new coronavirus, with main symptoms such as fever, cough, and difficulty breathing. In severe cases, it can lead to respiratory failure, multiple organ dysfunction, and even death.

Stroke refers to cerebral ischemia or hemorrhage caused by blockage or rupture of cerebral blood vessels, with main manifestations as sudden hemiplegia, speech disorders, decreased vision, etc. In severe cases, it can lead to disability, coma or even death.

What is the relationship between COVID-19 and stroke?

Like COVID-19 and other diseases that can cause severe inflammation throughout the body, inflammation and cytokine storms can cause the patient's blood to be in a hypercoagulable state, which may cause microthrombi to form in the blood and increase the risk of blood vessel rupture, leading to stroke, heart disease, and heart failure.

There is evidence that COVID-19 is an independent risk factor for acute ischemic stroke. Compared with patients without stroke, patients with COVID-19 complicated by acute stroke are more likely to have certain cardiovascular and cerebrovascular risk factors, such as old age, hypertension, diabetes, coronary heart disease, and severe infection. At the same time, patients with severe COVID-19 infection have a higher risk of acute stroke.

In addition, there are increasing reports of young people without typical cardiovascular and cerebrovascular risk factors suffering from COVID-19 and stroke, and these young people may sometimes only have mild respiratory symptoms.

The pathogenesis of COVID-19 complicated with stroke may include the following aspects:

Hypercoagulable state caused by systemic inflammatory response and cytokine storm: COVID-19 infection activates the body's immune system and produces a large number of cytokines, such as interleukin 6 (IL-6), interleukin 1 (IL-1), etc. These cytokines can promote the activation of the coagulation system, increase coagulation indicators such as fibrinogen and D-dimer, increase blood viscosity, form microthrombi or large thrombi, and block blood vessels in the brain or other parts.

Immune-mediated response after infection: After COVID-19 infection, the body may produce antibodies or immune cells against its own tissues or organs, such as anti-neuronal antibodies, anti-myelin antibodies, anti-endothelial cell antibodies, etc. These autoimmune reactions can damage the nervous system or vascular system, causing neuronal death or endothelial dysfunction.

COVID-19 directly induces infection of endothelial cells or neurons: COVID-19 enters cells by binding to ACE2 receptors on the surface of human cells. ACE2 receptors are widely distributed in multiple organs and tissues of the human body, including the nervous system and vascular system. Therefore, COVID-19 may directly infect endothelial cells or neurons, causing damage or death of endothelial cells or neurons.

How to prevent and treat stroke caused by COVID-19?

The main measure to prevent COVID-19 complicated with stroke is to prevent COVID-19 itself. The following measures are recommended:

Get vaccinated against COVID-19: Currently, a variety of COVID-19 vaccines have been approved for use in different countries and regions. These preventive vaccinations can effectively reduce the risk of infection with COVID-19.

Vaccine types and vaccination methods: Currently, a variety of COVID-19 preventive vaccines have been approved for use or emergency use in different countries and regions. These vaccines are mainly divided into the following categories :

Inactivated vaccines : Use inactivated coronavirus or some of its components, such as protein subunits or virus-like particles, to stimulate the body to produce antibodies. Inactivated vaccines usually require two or three doses and are administered by intramuscular injection. For example, the COVID-19 vaccines produced by Sinopharm, Sinovac-Kelvco, Bharat Biotech, etc. are inactivated vaccines.

Recombinant adenovirus vector vaccine : Use a modified non-pathogenic adenovirus as a vector to carry the spike protein gene of the new coronavirus. After entering human cells, the spike protein is expressed to stimulate the body to produce antibodies. Recombinant adenovirus vector vaccines usually require one or two doses and are administered by intramuscular injection. For example, the COVID-19 vaccines produced by Oxford/AstraZeneca, Janssen, and CanSino are recombinant adenovirus vector vaccines.

mRNA vaccines : use synthetic messenger RNA (mRNA) as the main component, carrying the spike protein gene of the new coronavirus, and instructing the cells to synthesize the spike protein after entering the human cells, stimulating the body to produce antibodies. mRNA vaccines usually require two doses and are administered by intramuscular injection. For example, the COVID-19 vaccines produced by Pfizer/BioNTech, Moderna, etc. are mRNA vaccines.

Safety and effectiveness of vaccines : All COVID-19 preventive vaccines approved for use in China or other countries and regions have undergone rigorous clinical trials and regulatory approvals, demonstrating their safety and effectiveness. Different types and brands of COVID-19 preventive vaccines may have different protective effects and side effect rates, but overall, they are all effective in preventing severe illness or death. Getting any COVID-19 preventive vaccine is much better than not getting any.

Vaccine recipients and procedures : The recipients and procedures of the COVID-19 preventive vaccine may vary according to the recommendations of health departments in different countries and regions or the World Health Organization (WHO). Generally speaking, it is recommended to give priority to high-risk groups, such as medical staff, the elderly, and patients with chronic diseases. Before vaccination, you should consult a doctor or vaccination institution to find out whether you are suitable for a certain vaccine and how many doses you need. After vaccination, you should pay attention to your physical reactions and seek medical attention in time if you feel unwell.

Nasal spray vaccine administration : In addition to the common intramuscular injection, there is a new type of administration method, which is nasal spray. Nasal spray vaccines use the mucous membrane in the nasal cavity to absorb vaccine ingredients and stimulate local and systemic immune responses in the respiratory tract. Nasal spray vaccines have the following advantages:

Closer to the natural infection route : The new coronavirus is mainly transmitted through the respiratory tract, and the nasal cavity is its primary invasion site. The nasal spray vaccine can form the first immune barrier to prevent the invasion of the new coronavirus in the respiratory tract, with rapid onset and long-lasting protection.

Broader spectrum of protection : Nasal spray vaccines can induce multiple immune responses, including innate immunity, T cell response, mucosal IgA antibody response and humoral IgG antibody response. These immune responses can fight against various mutant strains of the new coronavirus, including the Omicron variant.

A more friendly vaccination method : Nasal spray vaccines do not require syringes and needles, and can be administered through nasal spray. This can reduce injection-related adverse reactions and infection risks, save medical resources and costs, and improve vaccination convenience and coverage.

At present, my country has obtained emergency use approval for a nasal spray influenza virus vector COVID-19 preventive vaccine (referred to as "nasal spray COVID-19 vaccine"), which is the world's first nasal spray COVID-19 preventive vaccine to enter human clinical trials. The vaccine has completed Phase III clinical trials and obtained key data. The data show that the vaccine has good protective efficacy and safety against COVID-19 caused by the Omicron strain.