TORONTO -- As the COVID-19 pandemic spreads around the world, here is what you need to know about the signs and symptoms of the novel coronavirus and what to do if you think you may be infected.

SIGNS AND SYMPTOMS

The Public Health Agency of Canada (PHAC) says there are four main COVID-19 symptoms to watch out for:

  • fever
  • cough
  • difficulty breathing
  • pneumonia in both lungs

According to the World Health Organization (WHO), symptoms can also include:

  • tiredness
  • aches and pains
  • sore throat
  • diarrhea, nausea or runny nose in rare cases

The U.S. Centers for Disease Control (CDC) considers these "emergency warning signs" of a possible COVID-19 infection, but notes that the list is not all-inclusive.

  • fever
  • cough
  • shortness of breath or difficulty breathing
  • chills
  • repeated shaking with chills
  • muscle pain
  • headache
  • sore throat
  • new loss of taste or smell

Symptoms can occur anytime within 14 days of a patient's exposure to the virus – and, as the virus can be transmitted from one person to another, it can be difficult to pinpoint exactly when exposure occurred.

The symptoms are common ones when it comes to respiratory diseases. In addition to COVID-19, they can suggest a far more typical illness such as influenza or the common cold. Some of those who contract the virus may never display any symptoms, and may pass it on to others without realizing they ever had it.

This makes it virtually impossible for the average person to determine whether their symptoms are being caused by the new coronavirus or something else.

According to PHAC, there are three main ways the virus that causes the disease can be transmitted: close personal contact such as shaking hands, respiratory droplets spread through coughs and sneezes, and touching a surface with the virus on it then touching one's own face without first handwashing. Studies have shown that the virus can survive for up to 72 hours on plastic and stainless steel and less than 24 hours on cardboard.

HOW LONG IT LASTS

Once a person is exposed to the virus, it typically takes about five to six days before they begin to experience symptoms. However, symptoms can appear as early as one day after exposure and as late as 14 days after, according to the WHO.

Scientists are still learning how long a person is contagious, but a Chinese study of 191 patients observed that “viral shedding” — the process by which the virus replicates inside the body and is released — lasted for a median period of 20 days. The longest period of viral shedding researchers observed was 37 days.

How long a person is sick varies widely. About 80 per cent of COVID-19 patients are considered mild, and those patients typically recover within one to two weeks. More severe cases of the virus can last anywhere from three to six weeks, according to the WHO.

Dry coughing — a hallmark of COVID-19 — appears to be a lingering symptom and lasts about a week longer than fever, according to a Chinese study.

Shortness of breath is a major indicator of whether or not someone with COVID-19 requires hospitalization, and a Chinese study published last month in The Lancet suggests that shortness of breath begins about five to six days after the initial onset of symptoms.

The federal government has directed people with COVID-19 to isolate at home for 14 days.

The U.S. Centers for Disease Control (CDC) advises people who have COVID-19, but have not been tested, to not leave the home until they have had no fever for at least 72 hours, their other symptoms have improved, and at least seven days have passed since their symptoms first appeared.

OTHER POTENTIAL SYMPTOMS

There are also suggestions that COVID-19 might cause some patients to suddenly lose their senses of smell and/or taste, and several studies have found clues that pink eye, also known as conjunctivitis, could be an overlooked symptom and transmission method of the virus.

Doctors have also identified a new potential symptom in younger patients: skin lesions seen primarily on their toes.

The so-called "COVID toes" are often characterized by blueish-red or purple bumps on the toes that hurt or feel warm when touched. Physically, they look similar to frostbite, but notably develop without the extreme temperatures that trigger similar lesions.

These lesions primarily appear in younger patients — young adults or children — who have not displayed any other symptoms. They typically appear on the feet, but have also been observed on fingers.

Although there is not enough supporting research yet to make it one of the officially recognized symptoms of the virus, the Canadian Paediatric Surveillance Program has issued an alert warning doctors and parents about skin changes as a possible sign of infection. Doctors recommend that those who develope these lesions should self-isolate.

There's also growing evidence that COVID-19 can also cause the blood to clot in unusual ways, leading to reports of sudden strokes occurring in adults in their 30s and 40s who are not otherwise terribly ill.

As of April 28, there have been more than 49,000 cases of COVID-19 and 2,852 related deaths in Canada.

Although initially, the vast majority of the reported illnesses were linked to travel or people who had been in contact with recent travellers, community spread has become much more prevalent.

WHAT SHOULD I DO?

Advice for Canadians is evolving rapidly as the pandemic grows.

The federal government is urging all Canadians to stay at home unless it is absolutely necessary to go out in public. All travellers returning to the country and anyone who has had contact with a suspected or confirmed case of COVID-19 should self-isolate for 14 days. Some provinces have shut down non-essential businesses in order to further emphasize the need for physical distancing.

The government has also launched an online questionnaire that can be used as a self-assessment tool by anyone who is concerned that they may have COVID-19, and an app that provides up-to-date information and guidance regarding the virus.

The questionnaire advises whether users should visit an emergency room, contact telehealth, self-isolate or do nothing, and provides links to provincial and territorial advice when appropriate.

Those who must visit a health-care professional are advised to call ahead or tell them upon arrival that they have a respiratory illness. PHAC says that you may be asked to wear a mask to prevent the spread of the virus.

Doctors cannot provide any specific treatment for COVID-19 – there is no known cure or vaccine – but can ensure a patient's case is properly reported to public health authorities. The flu vaccine will not protect against the coronavirus.

Most people with mild symptoms of the coronavirus recover on their own.

"When you're sick, definitely stay home, cover your cough, wash your hands a lot. We can't repeat that too frequently," said Dr. Theresa Tam, Canada's chief officer of public health.

The WHO estimates that 80 per cent of COVID-19 patients will recover without the need for any medical intervention.

AVOIDING COVID-19

Even if you are not sick, public health officials are requiring "physical distancing," which includes avoiding large gatherings, working from home when possible, and keeping two metres between yourself and strangers when you venture outside. Businesses and organizations across the country, as well as different levels of government, have announced closures, reduced services and limits on crowd gatherings to encourage social distancing.

Just as the new coronavirus presents similarly to other respiratory illnesses, advice for keeping it at bay runs along the same lines as tips for avoiding more commonplace colds and coughs.

PHAC says that people who appear healthy can improve their chances of staying that way if they avoid close contact with people who are sick, do not touch their face with unwashed hands, regularly wash their hands with soap for 20 seconds or more, and use their sleeves to cover coughs and sneezes.

There is an increased risk of more severe outcomes for people who are 65 or older, who have compromised immune systems or who have other underlying medical conditions, the government agency said.

The risk for testing positive with COVID-19 may be increased on cruise ships, heavily affected areas and international conferences and other large indoor gatherings, PHAC said.

Additional recommendations for day-to-day life include immediately disposing of used tissues and regularly cleaning surfaces that come into contact with human hands, such as toilets, doorknobs and smartphones.

Surgical masks and N95 masks are best left to the frontline workers and health-care workers who desperately need them, as the country’s supply of personal protective equipment is low, but some experts are now saying that wearing homemade cloth face masks in some situations is a good idea for the general population.

“For example, if you’re in public transit and you cannot easily practice the two metres (of physical distancing), for example, then having that additional covering, like covering up your cough, I think, is a good idea,” Tam said in early April.

Several provincial health officials have started recommending the use of homemade face masks as well.

Wearing face masks will not protect you from the novel coronavirus, but does help those who are sick to not spread the virus. As there has been evidence of asymptomatic spread, wearing cloth face masks in public can cut down on the risk of a carrier who does not know they are sick from spreading it.

There is also no known evidence to suggest that animal-to-human infection has occurred in Canada. However, there are still "many unknowns" in this area, PHAC says, and a small handful of animals worldwide have tested positive, including two pet cats in New York state.

If you are diagnosed with COVID-19 and you have a pet, PHAC advises against snuggling or kissing your pet, sharing a bed with them, having your pet sit on your lap or letting them lick you.

PHAC advises that people with COVID-19 should have another member of your household care for your pet, limit your pet’s contact with other people and animals and wash your hands before touching or feeding them.

With files from The Associated Press and CTVNews.ca's Alexandra Mae Jones