With so much information circulating about SARS-CoV-2, the virus behind COVID-19, it helps to understand what viruses actually are and why they infect us. This article covers where they come from, how the body fights them, and how we can help the body respond to illness in the healthiest way available.
Why viruses need us to live
A virus exists for one purpose: to infect another organism — animal, plant, fungus or bacterium. It cannot live or reproduce without first infecting a living host cell. Having infected a host such as a human, the virus produces billions of copies of itself by hijacking that person's cells and using them to replicate. Once replicated, it goes on spreading from person to person.
What do viruses look like and what are they made of?
Each individual virus particle — a virion — is a small packet of genetic material, either DNA or RNA, wrapped in a protein coating called a capsid, sometimes with a further layer of lipids known as an envelope. Coronaviruses are enveloped RNA viruses.
Structure matters because it tells us where a virus is vulnerable. Soap, for instance, breaks down the lipid layer and pulls the virus apart — the same way it breaks down oil when you wash the dishes. That is why washing your hands frequently, for 20 seconds, with soap is so effective against SARS-CoV-2.
Structure also explains why antibiotics do not treat viral illness. Many antibiotics, penicillin among them, work by attacking the wall surrounding a bacterium. Viruses have no cell wall.
How big are viruses and why does it matter?
Viruses come in a range of shapes and sizes: circular, cylindrical, string-like, or studded with spikes as the coronaviruses are. SARS-CoV-2 is round and measures 60–140 nanometres. For scale, an inch contains 25.4 million nanometres; a centimetre contains 10 million.
Size determines which barriers are most likely to stop a virus entering through your nose and mouth when you wear a face mask.
SARS-CoV-2 spreads when respiratory droplets from an infected person's nose and mouth reach another person's nose, mouth or eyes. Cambridge scientists tested particles five times smaller than SARS-CoV-2, comparing homemade masks of various materials against surgical masks. The four most effective household materials were vacuum cleaner bags, tea towels, cotton and antimicrobial pillowcases.
What are novel (new) viruses and how do they emerge?
Novel viruses are simply viruses not seen before — SARS-CoV-2 being the example at hand.
Zoonotic diseases are animal viruses that have gone on to infect humans. This happens when an animal virus undergoes a genetic mutation allowing it to infect a new species successfully. Ordinarily, the genetic material of animal viruses is too dissimilar to establish an infection in humans.
On rare occasions animal coronaviruses do infect people, as happened with SARS-CoV-2. The animal of origin is likely a bat, and the virus may have passed through other animal hosts before infecting a human successfully.
What does it mean when a virus mutates?
Mutation is a natural part of every virus's life cycle. RNA-based viruses such as SARS-CoV-2 are genetically unstable and mutate at a considerably faster rate.
After infecting a new species, a virus keeps mutating, and those mutations can render it either more or less virulent. It is possible that certain mutations could make future vaccines less effective, or permit reinfection of someone who has already had the virus and developed immunity. Most viral experts, however, agree that this scenario is highly unlikely — though not impossible.
Why are novel viruses different from known viruses such as influenza and the common cold?
The longer a virus has been in circulation, the more likely it is that some portion of the population carries natural or vaccine-derived immunity — known as herd immunity — and that effective treatments have been established for those who fall ill.
With flu, for example, we know the likely course of the illness, the complications that may arise and the treatments that work. With a new virus there is no natural or vaccine-created immunity, so it can spread through the population very rapidly, and treatments for the sick are unknown.
How does your body respond when you are exposed to a virus?
The immune system's task is to judge whether what it encounters is safe or dangerous. When something is identified as dangerous — a virus, for instance — the immune system tries to destroy it and simultaneously activates an inflammatory response to assist the attack.
Early in that inflammatory response the body produces cytokines, chemical messengers that carry information about the virus to the rest of the body. These messengers have specific jobs, including raising body temperature to create a fever.
If this first line of defence proves insufficient, another part of the immune system — the adaptive immune system — takes over. It responds more slowly but is designed to target the virus with far greater accuracy. This is also the stage at which the body produces antibodies.
On first exposure to a virus you make antibodies specific to it. An antibody's job is to tag the virus for destruction by your immune system. Should you encounter the same virus again, those antibodies carry a memory and will ramp up to help fight the infection, frequently with greater accuracy the second time.
How long antibodies remain in the body varies by virus. And while people infected with COVID-19 do appear to produce antibodies, we do not know how long they will last.
What determines the type of illness a virus produces?
The symptoms a body produces, and the illness that results from any given virus, depend on which tissues the virus attaches to and how the immune system responds to the infection.
Coronaviruses, for example, bind to cells through receptors called angiotensin-converting enzyme 2 (ACE2), which are present at high levels in the lungs, intestines, kidneys and blood vessels. Symptoms therefore appear in the areas of the body richest in ACE2 receptors — which is why dry cough and shortness of breath are characteristic of COVID-19, the virus having entered through the nose and travelled into the respiratory system.
An important note on your daily medications. If you take a medication that works by increasing ACE2 receptors in the body, you may be at increased risk of contracting COVID-19 and developing complications. This is currently under study. Anyone taking NSAIDs such as ibuprofen, certain type II diabetes medications (TZDs), or blood pressure medications (ARBs and ACE inhibitors) should keep discussing this with their local physician.
What is a fever and why is it important?
Fever is the body's normal response to infection. Body temperature rises to create an environment hostile to the virus. High temperature also triggers production of infection-fighting white blood cells and inhibits the growth of both viruses and bacteria.
Bringing a fever down with medications such as paracetamol/acetaminophen, aspirin or ibuprofen interferes with the body's natural capacity to respond to infection. French doctors have also observed that treating COVID-19 patients with anti-inflammatory drugs such as ibuprofen and aspirin may worsen some cases and lead to pneumonia.
Short-lived mild fevers come and go without long-term complications, though the aches and pains felt during illness are partly attributable to the fever itself. Lowering it with medication may therefore improve comfort, but it will not help the virus run its course — and may in fact lengthen the time you are ill.
Staying hydrated during a fever is very important. Dehydration during illness can lead to serious complications. Adequate water intake — roughly 1 litre per 30 kg of body weight for an average healthy person — along with minerals from drinking broth, matters a great deal when body fluids are being lost through sweating, vomiting and diarrhoea.
Note: infants under 3 months are an exception and should always be seen by a doctor for any elevation in temperature. Do not give aspirin to children under 18, because of its link to the deadly Reye's syndrome. If you belong to a high-risk population, or have an unrelenting high fever, contact your doctor immediately.
What treatments are available for viruses?
Developing a vaccine for a new virus is a long process, often taking 18 months or more. Antiviral medications are difficult to develop too, because viruses are highly adaptive and replicate quickly, giving them many opportunities to mutate into resistance.
Medications already used against other viral infections can, however, be tested against a new virus. Fortunately, the development of a SARS-CoV-2 vaccine may be accelerated by the ability to repurpose vaccines that were already in development for SARS and MERS.
How to support your immune system to prevent viral illness
The basics of a healthy immune system:
Getting 7+ hours of sleep nightly
Reducing intake of refined sugar and processed food
Staying well hydrated with water
Prioritising daily exercise and movement
Engaging in regular stress management
Getting outdoors — nature, fresh air, sunshine
Stopping smoking
Limiting alcohol intake
No research has yet been done on which specific vitamins, minerals and herbs are effective for preventing and treating COVID-19, but there is research on their effectiveness against other viruses — other coronaviruses, influenza and the common cold. A list of products for preventing viral illness might include vitamin C, vitamin D, zinc, elderberry syrup and echinacea, alongside a diet containing garlic, onion, ginger, mushrooms, and colourful fruits and vegetables rich in potent anti-inflammatory compounds.
SARS-CoV-2 can multiply in the nose and throat for days before moving into the lungs, so I also recommend daily nasal irrigation, along with zinc lozenges, throat sprays, and gargling a solution of water and antimicrobial herbs.
