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The Sure Sign You Have COVID, According to a Doctor

The very latest on what we know about coronavirus.

As a doctor, I'll never forget December 2019, when the first cases of a mysterious virus were reported in Wuhan, China. Initially, this was known as the "severe acute respiratory coronavirus syndrome virus" – SARS-Co-V-2. Subsequently, the virus was officially named Coronavirus 2019, now shortened to COVID-19. And what a year it has been!

As I write, the World Health Organization has confirmed more than 64 million cases around the world, and 1.48 million deaths. We're living through a global viral pandemic which has changed our lives in a way we never could've imagined. Incredible that a minuscule virus—100 million COVID-19 viruses can fit on a pinhead—has wrought such havoc and devastation.

Here's the latest on what we know about COVID-19, its symptoms in adults, and what you can do to ease symptoms if you contract it. Read on, and to ensure your health and the health of others, don't miss these Sure Signs You've Already Had Coronavirus.


What Are COVID-19 Symptoms?


It takes about five days after you've been exposed to the virus for symptoms to appear. Around 97.5% of people who develop symptoms do so within 11.5 days.

Over the past ten months, statistics have been collected about the type and frequency of COVID symptoms. At the outset, we were told to look out for a dry cough and fever, but more recent information suggests other symptoms may be even more common. A recent European study of 1,420 patients admitted to 18 hospitals across Europe reported COVID symptoms in the following order of frequency:

  • Headache 70.3%
  • Loss of smell 70.2%
  • Nasal obstruction 67.8%
  • Cough 63.2%
  • Weakness 63.3%
  • Muscle pains 65.2%
  • Runny nose 61.1%
  • Loss of appetite 54.2%
  • Sore throat 52.9%
  • Fever 45.4%

Interestingly, groups of symptoms differed according to age and sex.

  • Younger patients more often had ear, nose, and throat symptoms. 
  • Older patients more often had fever, loss of appetite, and fatigue.
  • Loss of smell, fatigue, headache, and nasal obstruction were more common in females.

In another recent publication in the BMJ, the authors studied 20,133 patients hospitalized with COVID-19. They found that symptoms appeared to be in clusters: A respiratory cluster (cough, shortness of breath, sputum, and fever), a musculoskeletal cluster (joint pain, headache and fatigue), and a gastrointestinal cluster (abdominal pain, diarrhea, and vomiting.) 


The One Sure Sign is That You Could Lose Your Sense of Smell

Portrait of young woman smelling a fresh and sweet nectarine

Loss of sense of taste or smell was also reported by 55% of adults aged 18-65 years, as early COVID-19 symptoms. It was less commonly reported in younger (21%) or older (26%) age groups.

ENT specialists are still unsure if the loss of sense of taste or smell occurs because the COVID-19 virus directly damages the olfactory nerve, or whether this is due to nasal inflammation and obstruction.


How Many COVID Patients Are Asymptomatic?

Friends in the Pub

Many patients who become infected with COVID-19 don't experience any symptoms. But just how common is that? In April, the CEBM tried to answer this question. They tabulated the results from various sources and concluded

  • 5% – 80% of COVID patients are asymptomatic
  • Some asymptomatic cases will go on to develop symptoms 
  • Children and young adults often have no symptoms

NBC News reported on a study of 217 people on a cruise ship traveling from Australia to Antarctica. There, 59% tested positive for COVID-19, but only 19% had any symptoms. A full 81% were asymptomatic.

In another recent publication in JAMA Internal Medicine, the authors studied 303 patients admitted to the hospital with COVID-19 in Cheonan, South Korea. Of them, 110 were asymptomatic before they started self-isolating. However, a further 21 developed symptoms between day 13 and day 20 of isolation. 

Of note, the study showed that the asymptomatic group had the same amount of virus in their noses, throats, and lungs as patients with symptoms. The authors commented that those with asymptomatic infection 'don't look any different' from those with symptoms. They may be less efficient at transmitting the virus as they are not coughing or sneezing. However, the difference is that people with symptoms know they have the virus and stay at home. Those who are unaware they have it continue their normal daily activities and spread more virus. 


Asymptomatic COVID And "Super-Spreaders"

Woman at the local market's checkout paying by debit card

You can't tell who is infected with COVID-19. Look around you; it could be anyone. The problem is that some people spread more virus than others. The average person with COVID infects 1.3 to 3.5 other people. If you infect more people than this, you're called a "super-spreader."

Super-spreaders may

  • have an occupation which gives them a high contact rate with other people, such as a shopkeeper, a hairdresser or a waitress 
  • travel frequently; they may often use public transportation or be globetrotters
  • participate in group events or mass gatherings, for example, sing in a choir or attend regular church services
  • not comply with infection-control measures; studies show up to 50% of people carry on as normal in a pandemic and don't stick to the rules
  • just spread more virus, for reasons which are unclear, possibly genetic.

Data from previous outbreaks has shown that 20% of the population are responsible for 80% of infections. 

Most people would not want to unknowingly infect another person. Any of us could be infected. It's imperative we all act responsibly and follow the infection-control rules. 

As the pandemic progresses, young adults are now considered the most likely super-spreaders. Lately, the biggest increases in infections in the UK have been in adults aged 20 to 29. Young adults perhaps mistakenly believe that the virus is only dangerous for older people. This is far from the truth. In the US, for example, 1 in 5 of the first 4,226 patients hospitalized for COVID-19 were age 20 to 44. 

Authorities are concerned that as lockdown rules have eased, young adults have become complacent. They need to remember the virus has not gone away. All the rules still need to be followed. Each time we flout the guidelines, we risk infecting someone who may not fare well with the infection. It may or may not be you, but it could be your parents, grandparents, and/or any other elderly or sick, neighbors and friends. 

What does all this mean? It means you can never tell who could be infected with the virus. That's why to stay safe, you need to keep at least six feet away from other people who are not in your household, cover your nose and mouth with a face mask, wash your hands regularly and carefully follow all the rules on social distancing.

RELATED: Unhealthiest Habits on the Planet, According to Doctors


What To Do If You Think You Have COVID Symptoms

Young man suffering from cold at his home

If you think you might have COVID-19, take advice from the CDC website.


How To Treat Mild COVID Symptoms At Home

young woman sitting on a couch having a strong headache

There are no current effective treatments for COVID-19. COVID-19 is a virus, and antibiotics do not kill viruses, so there is no indication for antibiotics. All you can do is take care of yourself, rest and wait for your body to produce antibodies which destroy the virus. 

Four out of 5 people will have recovered from the virus within two to four weeks.

Here is some simple advice on how to treat COVID symptoms at home:

  • Rest. Your body needs energy to fight the virus. Don't feel guilty about putting your feet up, taking a nap or not getting chores done. You need to take it easy and look after yourself. 
  • Drink plenty of fluids. Have a jug of cool water nearby and take regular sips often. You lose more water when you have a fever and can easily get dehydrated, and you need to keep your circulation topped up.
  • Keep cool. Sit by an open window, but don't use a fan as this increases the risk of transmitting the virus. Use a cool cloth on your forehead, suck ice cubes, take a cool bath or shower. Acetaminophen and ibuprofen can be taken to lower a fever.
  • Coughing can be very troublesome. Drinking warm lemon and honey is as effective as any cough medicine and can soothe a sore throat.  
  • For most people, breathlessness will pass. In a small number of cases, as the infection progresses and your oxygen levels fall, breathlessness worsens. Five to 15% of COVID patients eventually need admission to intensive care for breathing assistance and sometimes use of a ventilator.
  • Remember to take all your usual medication, including the use of any inhalers.
  • Rest and sleep. You will be tired when you're ill, as your body is using all its energy to make antibodies and deal with the other effects of the infection. 
  • Help yourself by planning ahead. For example: organize once-weekly grocery shopping with home delivery, and cook simple pre-prepared meals. Accept help from family, friends, and neighbors. Eat small nourishing meals often. Don't push yourself—all those jobs just have to wait.


How to Treat Breathlessness

Asian woman having difficulty breathing in bedroom at night

Your breathing can change rapidly in hours or minutes. If you're at all concerned, don't wait—seek help right away. It's also virtually impossible to assess your own breathing properly. 

Curiously, many COVID patients don't realize how breathless they are. This is an unexplained phenomenon of the disease called "happy hypoxemia." Because of this, many patients and their caretakers don't seem to be aware how serious their breathing has become. That can lead to a delay in admission to the hospital. 

Here are some tips to strengthen your lungs and treat shortness of breath.

  • Sit up straight. A chair may be better than a bed or prop yourself up with lots of pillows. Sometimes holding onto something in front of you like a table or a cushion can help.
  • Try to keep calm. Getting anxious makes breathlessness worse.
  • Get into a good breathing rhythm. Breathe in slowly as you count to one, then breathe out slowly as you count two and three. Always breathe longer as you breathe out than when you breathe in. Otherwise, you end up panting and retain carbon dioxide, which is counterproductive. Remember you need to breathe out effectively to empty your lungs, so you have room to fill them with more air.
  • Keep the room well humidified. You can produce steam from a pan of boiling water (take extreme care if you do this) or use of a humidifier. Steam helps unclog mucus. A hot shower or a steamy bath can help.
  • Try to "huff" for 10 minutes, three times a day. Sit up straight and breathe out forcefully once or twice, as if you were polishing a mirror. This will make you cough, which is good—it loosens the mucus in your chest. 


When To Make An Emergency Call

Doctor nurse in protective face mask listening to breath with a stethoscope suspecting Coronavirus (COVID-19).

If you're concerned that your condition is getting worse, call 911 for help without delay.

Here are some worrying symptoms. This list is not exhaustive, just some common scenarios.  If you are unsure, don't delay. Get help.

  • You're increasingly breathless; it's getting harder to speak
  • Your lips, fingers and toes look blue
  • You're exhausted, agitated or confused
  • You've got chest pain
  • You feel drowsy

RELATED: COVID Symptoms Usually Appear in This Order, Study Finds


If It's Not COVID, What Else Could It Be?

woman video chat doctor

When you feel ill and think it might be COVID, there are many other infections/conditions this could be. If your symptoms are mild and improving, it's safe to stay at home, rest and give your body time to fight the infection.

However, if you are seriously ill or your symptoms are worsening, you must seek help ASAP. The medical team will take your history, examine you, and organize tests depending on your symptoms and signs. 

Here some possible causes for your symptoms, other than COVID-19.

Viral infections

  • Influenza affects around 10% of the population every year.
  • Respiratory syncytial virus (RSV) most commonly affects babies and young children, where it can cause bronchiolitis. However, it also affects the elderly. 
  • Parainfluenza virus commonly causes croup in babies and young children, but it also causes bronchitis and pneumonia in older adults.
  • Human metapneumovirus typically affects babies, young children, older adults and those with a weakened immune system.
  • Adenovirus is very common in the winter months and affects all age groups, causing a common cold, croup, bronchitis, and pneumonia.
  • Hantavirus pulmonary syndrome. Viruses spread by rats and mice can cause similar symptoms to COVID-19. These infections are rare and occur in people who work in pest control.

Bacterial infections

  • Streptococcus pneumoniae causes pneumonia in the winter months. It can affect babies, children, and adults. You can be given a protective pneumococcal vaccination.
  • Haemophilus influenzae. Babies are now immunized against this bacteria. Infection is far less common and can cause pneumonia and meningitis. 
  • Moxarella catarrhalis. A common cause of otitis media (ear infection) in children, this bacterium can cause pneumonia in older adults, especially in those with underlying lung conditions.
  • Atypical bacterial pneumonia. The most common are mycoplasma, chlamydia, and Legionella pneumoniae.

Sepsis is a life-threatening medical emergency. The symptoms can mimic those of a severe COVID-19 infection.

Non-infectious causes

  • Heart failure. When the heart is not pumping properly, the lungs can fill with fluid.
  • Pulmonary embolus is a blood clot in the lung, which makes you feel suddenly unwell and breathless. 
  • Salicylate poisoning is an aspirin overdose, which can cause acute pulmonary edema, or fluid build-up in the lungs.

Skin conditions 

Many different skin conditions have been reported with COVID, but they may be confused with varicella zoster, urticaria (hives), chilblains or purpuric gloves and socks syndrome.


The Changing Face Of The Virus

Two Medical Scientists in the Brain Research Laboratory Discussing Progress on the Neurophysiology Project Curing Tumors.

As the pandemic continues, various factors about the infection are becoming apparent.

The virus seems to be less deadly. 

For example, in the UK, Oxford University quoted a crude death rate of 18% in April, but only 1% in August.  

This may be because the virus is mutating, the highest rates in infection are now seen in younger adults (who are more likely to survive the infection), and/or because hospitals are getting better at treating the infection.

The immune response to COVID-19 is still not well understood. 

It takes about 10 days for antibody production to get underway. Those who have the most severe infections tend to have the strongest antibody response. It's still not clear why some people have a poor antibody response—or, for those who do have a good antibody response, how long-lasting that response will be. Only time will tell. There has been one recently reported case in Hong Kong of a patient who became infected with COVID-19 for a second time.

There can be long-term complications. 

For some COVID patients, symptoms can be long-lasting. The BBC reports that 300,000 patients have symptoms lasting longer than four weeks, and 60,000 have had symptoms for at least 3 months. This is called "Long COVID."

A huge range of symptoms can persist after COVID, ranging from ongoing breathlessness, tiredness, muscle fatigue, and mental health conditions such as PTSD, anxiety and depression. 

RELATED: 7 Side Effects of Wearing a Face Mask


What Can You Do To Help Yourself?

couple checking food label at the store

To stay well, be alert, be informed, follow infection-control guidelines, and be in the best health you can.

Know the COVID symptoms and what to look out for. But remember, COVID is all around us, and many people are carrying and spreading the virus who have no idea they have it. To protect yourself and those you love, practice social distancing, wear a mask, and wash your hands. Remember: 20% of the population cause 80% of COVID infections. Don't let yourself be one of that 20%. And to get through this pandemic at your healthiest, don't miss these 35 Places You're Most Likely to Catch COVID.

Deborah Lee, MD
Dr. Deborah Lee is a health and medical writer with an emphasis on women's health. Read more about Deborah