Coronaviruses are a large family of viruses that may cause a range of illnesses in humans, from the common cold to SARS. Viruses of this family also cause a number of animal diseases.
Pandemic Coronavirus (COVID-19)
On December 31, 2019 the WHO China Country Office was informed of cases of pneumonia of unknown etiology detected in Wuhan City, Hubei Province of China. The outbreak began in a seafood and poultry market in Wuhan, a city of 11 million in central China. Like SARS-CoV and MERS-CoV, the newly detected coronavirus (SARS CoV-2) has a zoonotic source, however, human to human transmission has been confirmed. On March 11, 2020 the WHO declared COVID-19 viral disease a pandemic. On May 4, 2023, the International Health Regulations (IHR) Emergency Committee of the WHO downgraded the COVID-19 pandemic. The committee determined that COVID-19 is now an established and ongoing health issue which no longer constitutes a public health emergency of international concern (PHEIC).
Epidemiology of COVID-19
As of April 12, 2023 a total of 4,641,301 confirmed cases caused by the novel Coronavirus COVID-19 (SARS-CoV-2) and 52,247 deaths were reported in Canada. An Epidemiological Summary of COVID-19 Cases in Canada is available.
The first human infections in China must have occurred in November 2019 or earlier. The first 59 suspected cases at the end of December 2019 and early January 2020 were admitted to Jinyintan Hospital, which was specially designated to isolate them.
On January 23, 2020, Chinese authorities closed off the city, canceling planes and trains leaving Wuhan and suspending buses, subways and ferry services. A second city in China, Huanggang was also placed in lockdown. On January 24, 2020 travel was restricted to a total of 10 cities, affecting 50 million people. Public bus, railway and airline operations were also suspended in these cities. On January 30, 2020 the World Health Organization (WHO) announced that the novel coronavirus is considered a public health emergency of international concern (PHEIC). The International Health Regulations Emergency Committee announcement this decision due to concern for further global spread after person-to-person spread of the novel coronavirus (COVID-19) was confirmed in 4 countries (Germany, Japan, Vietnam and the United States) outside of China. As for February 5, 2020, forty major airlines around the world have canceled or reduced their flights to China until as late as March amid the coronavirus outbreak. On February 19 and 21, 2020; cases were reported in Iran and Italy respectively with no known direct link to Mainland China. On March 9, 2020 Italy expanded the quarantine from the Lombardy region to the entire country, as Italy’s case count surged. People throughout the country of 60 million were ordered not to travel other than for work or emergencies. South Korea and Iran have also imposed travel restrictions. On March 11, 2020 the WHO declared COVID-19 viral disease a pandemic. As of March 25, 2020 the virus had spread to 192 countries with travel bans and restrictions implemented in many countries combined with various social distancing measures (ie. school, public space closures) in an effort to slow COVID-19 spread and flatten the epidemiological curve.
Preliminary calculations for the average number of infections that each infected person may go on to cause, known as R0. This is estimated to be 2.0 to 3.0 people per infected person. In comparison to seasonal flu, which usually has an R0 of around 1.3.
The World Health Organization announced that the fatality rate in Wuhan, China, considered the epicenter of the outbreak, is between 2% and 4%. Outside of Wuhan, it is thought to be closer to 0.7%. In a recent JAMA paper The overall case-fatality rate was 2.3%. No deaths occurred in those aged 9 years and younger, in those aged 70 to 79 years had an 8% fatality rate and those aged 80 years and older had a fatality rate of 14.8%. Children made up a 2.4% of the cases and almost none was severely ill. The fatality rate was 49% among critical cases, and elevated among those with preexisting conditions: 10.5% for people with cardiovascular disease, 7.3% for diabetes, 6.3% for chronic respiratory disease, 6% for hypertension, and 5.6% for cancer.
A conjoint review done by WHO and Chinese scientists has found that 80% of infected people had mild to moderate disease, 13.8% had severe symptoms, and 6.1% had life-threatening episodes of respiratory failure, septic shock, or organ failure. No deaths were reported among mild and severe cases. For the mild and moderate cases, it took 2 weeks on average to recover.
Variants of the Virus that Causes COVID-19
Genetic variations of viruses such as the one that causes COVID-19 are not uncommon and many other variants of the SARS-CoV-2 virus have been previously observed around the world this year. Both new variants include mutations (i.e., changes to the genetic material in the virus) on the “spike” protein, which may result in the virus becoming more infectious and spreading more easily between people. These variants have been termed variants of concern (VOCs) and have been associated with evidence of increased transmissibility, severity, and/or possible immune evasion with potential implications for reinfection and vaccine effectiveness
Multiple variants of the virus that causes COVID-19 are circulating globally:
The United Kingdom (UK) identified a variant called B.1.1.7 (501Y.V1, VOC 202012/01), also referred to as Alpha with a large number of mutations in the fall of 2020. This variant spreads more easily and quickly than other variants.
The variant B.1.351 (Beta) emerged in South Africa. Originally detected in early October 2020, B.1.351(501Y.V2) shares some mutations with B.1.1.7.
In Brazil, a variant called Gamma (P.1, previously P.1.1.28) emerged in January 2021. This variant was first identified in travelers from Brazil, who were tested during routine screening at an airport in Japan. This variant contains a set of additional mutations that may affect its ability to be recognized by antibodies.
The Delta (B.1.617.2) variant was identified in India. The Delta variant causes more infections and spreads faster than early forms of SARS-CoV-2.
South Africa identified the variant Omicron (B.1.1.529) in November 2021. There is an increased risk of reinfection with Omicron, as compared to other variants of concern. Omicron is more transmissible but causes less severe disease compared to Delta infections. Nonetheless, due to increased transmission of Omicron, an increase in the number of severe cases is occurring and poses a significant threat to health system capacity. There is insufficient data to comment on mortality and long-term COVID outcomes. The variant is not a single strain, but rather a family sublineages: BA.1, BA.2, BA.3, BA.4 and BA.5. As of March, 2022 the BA.2, a sub-variant of the Omicron coronavirus variant, had become dominant globally, representing nearly 86 percent of all sequenced cases, according to the World Health Organization. However, by summer of 2022 the BA.4 and BA.5 sublineages had beome dominant globally.
For more information of COVID-19 Variants of Concern, click here.
Surveillance for COVID-19 Infection
Provincial/Territorial public health authorities should report confirmed and probable cases of COVID-19 nationally to the Public Health Agency of Canada within 24 hours of their own notification.
A person with confirmation of infection with SARS-CoV-2 documented by:
The detection of at least 1 specific gene target by a validated laboratory-based nucleic acid amplification test (NAAT) assay (e.g. real-time PCR or nucleic acid sequencing) performed at a community, hospital, or reference laboratory (the National Microbiology Laboratory or a provincial public health laboratory) or
The detection of at least 1 specific gene target by a validated point-of-care (POC) NAAT that has been deemed acceptable to provide a final result (i.e. does not require confirmatory testing) or
Seroconversion or diagnostic rise (at least 4-fold or greater from baseline) in viral specific antibody titre in serum or plasma using a validated laboratory-based serological assay for SARS-CoV-2
Probable case
A person who:
1. Has symptoms compatible with COVID-19
and
Had a high-risk exposure with a confirmed COVID-19 case (i.e. close contact) or was exposed to a known cluster or outbreak of COVID-19
and
Has not had a laboratory-based NAAT assay for SARS-CoV-2 completed or the result is inconclusive
or
Had SARS-CoV-2 antibodies detected in a single serum, plasma, or whole blood sample using a validated laboratory-based serological assay for SARS-CoV-2 collected within 4 weeks of symptom onset
or
2. Had a POC NAAT or POC antigen test for SARS-CoV-2 completed and the result is preliminary (presumptive) positive
or
3. Had a validated POC antigen test for SARS-CoV-2 completed and the result is positive
Symptoms of COVID-19
Illnesses associated with the new coronavirus, named COVID-19, are similar to several respiratory illnesses and include fever, dry cough, sore throat and headache. Less frequent symptoms included coughing sputum or blood, headache and diarrhea. Most cases are considered mild to moderate with a subset experiencing more severe illness with shortness of breath and difficulty breathing.
Reported signs and symptoms include:
Fever
Coughing
Difficulty breathing
Pneumonia in both lungs
Fatigue
Sputum production
Sudden loss of taste or smell
Anorexia
Myalgia
Runny nose
Diarrhea
Nausea
Treatment and Vaccine for COVID-19
Remdesivir (brand name Veklury) is currently the only drug authorized with conditions to treat COVID-19 in those who are hospitalized with severe symptoms. On January 17, 2022 Health Canada authorized the combination of two antiviral drugs, nirmatrelvir and ritonavir (brand name Paxlovid) to treat adults with mild to moderate COVID-19 who are at high risk of progressing to serious disease, including hospitalization or death. For more information about treatment click here.
On Nov. 18, Pfizer released updated results of its Phase 3 clinical trials, suggesting the vaccine is 95 per cent effective at preventing COVID-19, a little over a week after releasing interim results showing the vaccine may be 90 per cent effective. Moderna announced on Nov. 16 that preliminary data from its ongoing Phase 3 clinical trial shows the vaccine is 94.5 per cent effective at preventing COVID-19. On Nov 23, Astra Zeneca announced their vaccine appeared to be 70 per cent effective against the novel coronavirus. On Jan 21, 2021 Johnson and Johnson announced their vaccine was 85% effective overall in preventing severe disease and demonstrated complete protection against COVID-19 related hospitalization and death as of day 28. For more information on COVID-19 vaccines click here.
Infection Prevention and Control
Prior to any patient interaction, all healthcare workers (HCWs) have a responsibility to assess the infectious risk posed to themselves and to other patients, visitors, and HCWs. This risk assessment is based on professional judgment about the clinical situation and up-to-date information on how the specific healthcare organization has designed and implemented engineering and administrative controls, along with the availability and use of personal protective equipment (PPE).
In response to the emergence of COVID-19 variant B.1.1.529 (Omicron variant) recommendations for infection prevention and control measures for direct care of patients with suspected or confirmed COVID-19 in healthcare settings include:
Well fitted respirator
eye protection (e.g., goggles or face shield)
gowns
gloves
Recommended PPE for all patient encounters should be based on a point of care risk assessment (PCRA), which should consider:
community epidemiology of COVID-19
ventilation assessed by the organization as adequate
crowding and occupancy of spaces
patient not yet clinically evaluated (e.g., Emergency Areas)
likelihood of exposure to SARS-CoV-2 and other pathogens based on:
specific interaction
specific task
specific patient
specific environment, and
available conditions
Additional recommendations include:
Continue to adhere to, reinforce, evaluate and monitor the full range of existing COVID-19 infection prevention and control measures and guidance
Continue to implement and re-evaluate the hierarchy of controls within the healthcare environment including:
engineering and administrative controls
all HCWs should be vaccinated with booster vaccines
processes and written procedures to manage HCW exposures to COVID-19 and illness
environmental cleaning and disinfection
active screening and notification
physical distancing
As information becomes available, these recommendations will be re-evaluated and updated as needed. HCWs should refer to provincial and territorial guidance and facility policies on specific recommendations for use of medical masks, eye protection and other PPE, as well as PPE conservation strategies.
