Understanding the ‘cytokine storm’ that is Covid-19

I was on vacation in Japan around Christmas when I first heard the news on CNN, of a strange virus that was causing pneumonia in a cluster of patients in  Wuhan. On reading the report on my smartphone, I felt a shiver down my spine. This was because the description of the illness resembled the “cytokine storm” of the Sars virus. The shiver down my spine was prescient; as of current writing we are in Dorscon Orange with 86 patients diagnosed, 5 in intensive care and 47 patients discharged and well.

In China, despite the heroic and unprecedented actions of locking down an entire province, the epidemic rages on. The silver lining is that the heroic actions by the Chinese have bought us some time for our local actions to take effect. So what is this “cytokine storm” that you keep hearing about? In essence when a virus attacks a host, it is like an invasion. The virus lands on a beachhead – in humans it is usually in the throat – and starts multiplying in large numbers.

When there is a high viral concentration or viral load, the virus enters the blood stream or moves through lymphatic system or via secretions, and can spread to other organs. In the case of Covid-19, it spreads deeper into the lungs where it targets a receptor called the Angiotensin Converting Enzyme receptor. Why do some patients have a mild disease while others are warded in intensive care? This is because when there is a huge viral load, the body responds massively. In healthcare workers, our immune systems are constantly challenged as we meet lots of patients daily and are exposed to the viruses or bacteria that they carry.

Our immune system is primed to deliver an overwhelming response especially in the face of a huge viral load. It is precisely this overwhelming response that may make us very ill and be warded into intensive care. So, you may not realise that our healthcare workers are under a great deal of stress during this period as our risk is way higher than the average patient.

As for the public, what should they be aware of so that they can help themselves? We know the virus is spread via droplets. This means that when someone coughs, the droplets fly through the air for about 10 feet (three metres) and settle on surfaces. The mucus in the droplet protects the virus whilst the droplet is on a surface. The mucus usually dries up in 30 to 60 minutes and the virus dies. However, when an unsuspecting person touches the surface with his hands and  then proceeds to touch his eyes, face or hair, the virus can then be transmitted. The entry to a host is usually via mucus membranes; these line the inside of our mouth, nose and eyes. As for the hair, the droplet can cling onto hair and be protected by headgear. Hence, I tell my patients that hand hygiene is of the utmost importance and they must always wash their hands before they touch their eyes, face or flick their hair.

Do we really need to use hand sanitisers for hand hygiene? The reality is that soap and water will do. We also know that the coronavirus is quickly inactivated by plain tap water. However, we must get rid of the mucus envelope that protects the virus. Hence the soap is useful and for surfaces we need to ensure that the droplets with attendant load of mucus is cleaned off. We then come to masks. The current advice is that masks are useful for preventing those who are sick from infecting those who are well. The surgical mask is enough to stop droplet transmission.

There is no need to wear the N95 mask. In fact, when you wear the N95 mask for a period of time, you will get fatigue from breathing against resistance. Therefore, we do not encourage patients with chronic heart or lung diseases to wear N95 masks routinely. For healthcare workers who wear N95 masks for a long duration, we do feel the effects of that added work of breathing at the end of the day. For those who are well, should they wear masks? The perspective is that we have 30,000 to 35,000 patients daily in Singapore with upper respiratory infections of all sorts. Maybe a couple of hundred will be pneumonia cases and Covid-19 infections will probably number less than two handfuls. The idea is to avoid crowds as we cannot contact trace a crowd of people. However, I tell my patients that life must go on and if you are meeting your family members, friends and colleagues for a meal, contact tracing is simple as you know everyone.

As for fear of the virus, this is the stuff that epidemics are made of. The difference between Sars, H1N1 and the current situation is that the feed from social media is massive. We are constantly inundated by chats, videos and articles coming through our smartphones. The fear captures and amplifies the individual’s mind and soon he or she starts to think or say things in an illogical manner. This is so obvious when you are reading the feed from chatgroups.

When we are angered by a close shave, such as when an office colleague is ordered to be quarantined, we tend to think the worst of our colleagues. When we are fatigued and tired at the end of the day from our workload and our worries about the virus, and we read of the demise of the eye surgeon in Wuhan and his pregnant wife, you think of the safety of your family and are worried sick. When we receive news or read something that reflects our emotional state, our brain tends to amplify or exaggerate the pervasiveness, degree and severity of that situation.

It is important that we trust the experts, or make sure that our news comes from reliable sources and sieve out misinformation and fake news. Please do not believe claims that the virus is airborne, conspiracy theories on the origin of the virus, need for the whole population to wear masks or false claims about the competence of health authorities and governments. In Singapore, our leadership has the institutional memory of the Sars epidemic and the dress rehearsal of the H1N1 pandemic. We also have the logistics, preparation and the physical capability in terms of isolation rooms and intensive care. Most importantly, the leadership has the political will to take tough action when necessary and the people will listen, respond and act responsibly when we need to. As we speak, the Public Health Preparedness Clinics are being activated. Do spare a thought for our healthcare workers as they strive and struggle in the days ahead, often with their own burdens, fears and tensions pushed aside for the heroic task at hand.

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