The Ontario government announced a new COVID-19 response framework, which will allow the province to rank health units based on case numbers and trends, using colour-coded categories.

Each week, the health units will be reassessed and placed into a category — a plan that Premier Doug Ford said will serve as an "early warning system," helping the province to "scale up and scale back public health restrictions on a regional or community basis in response to surges and waves of COVID-19."

Here is what to expect from the colour-coded levels:

Green (Prevent)

What it is: The "green" level, also known as the "prevent" level, will put a health unit into a state similar to the former Stage 3, with loosened restrictions and only certain high-risk locations remaining closed.

What it looks like: Some proposed restrictions for this level include a two-metre distance between tables at dining establishments; nightclubs operating as restaurants or bars; allowing a maximum of 50 people inside gyms or fitness centres; limiting fitting room capacity at retail stores; closing oxygen bars, steam rooms, saunas and whirlpools in personal-care facilities; and limiting capacity to 50 people at gaming establishments.

How to get there: Health units at this level will have a weekly rate of less than 10 cases per 100,000 people and a positivity rate of less than one per cent.

Yellow (Protect)

What it is: The "yellow" or "protect" level means health units will see increased measures and guidelines for businesses or organizations that are open.

What it looks like: Some proposed restrictions for this level include liquor only being sold or served between 9 a.m. and 11 p.m.; required face coverings at sports and recreation facilities, except when exercising; limited volume of music at retail locations; and required contact information from customers at some establishments.

How to get there: The health units at this level are required to have a weekly rate of 10 to 39.9 cases per 100,000 people and a positivity rate of one to 2.5 per cent.

Orange (Restrict)

What it is: Health units at the "orange" or "restrict" level will see restrictions enhanced further from the "protect" level.

What it looks like: Some proposed restrictions for this level include limiting capacity at meeting and event spaces to 50 people per facility; limiting operating hours for businesses; enhancing screening measures at various businesses and establishments; prohibiting personal care services that require the removal of a face mask; and limiting capacity in retail locations.

How to get there: These health units will have a weekly incidence rate of 40 to 99.9 per 100,000 people and a positivity rate ranging from 2.5 to 9.9 per cent.

Red (Control)

What it is: The "red" or "control" level means a return to modified Stage 2, with further restrictions and the closure of some businesses or organizations.

What it looks like: Some proposed restrictions for this level include prohibiting indoor dining; closing gyms and indoor fitness centres; closing cinemas; closing casinos, bingo halls and other gaming establishments; and limiting capacity at indoor event spaces to 10 people per facility.

How to get there: The health units at this level will have a weekly incidence rate of more than 100 cases per 100,000 people and a positivity rate of more than 10 per cent.

Gray (Lockdown)

At this level, health units would return to a modified Stage 1 and a declaration of emergency will be considered.

The Public Health Agency of Canada (PHAC) now says the novel coronavirus can be transmitted through small airborne droplets.

PHAC updated its virus transmission guidance part of a larger overhaul of COVID-19 advice that also included a new recommendation that all face masks should contain three layers of material.

Previously the agency had said that COVID-19 “most commonly” spreads through touching a contaminated surface or having close contact with an infected person who passes the virus along through droplets created when they speak, cough, sneeze or otherwise project form their mouth.

These droplets were thought to fall to the ground very quickly. The new guidance notes that this can take “seconds or minutes,” and that infection can also be transmitted through aerosols – smaller droplets that “linger in the air under some circumstances.”

According to the new guidance, the droplets and aerosols can infect a person by being inhaled or by otherwise coming into contact with the mouth, nose, or eyes.

Contact with contaminated surfaces, followed by touching the face without first handwashing, remains in the guidance as another potential method of transmission.

Canada’s chief public health officer referenced the new guidance at a press conference with Prime Minister Justin Trudeau and other cabinet members.

“This is why we have been advising Canadians to try to avoid the three Cs – closed spaces with poor ventilation, crowded places with large numbers of people gathered and close contact situations where you can’t maintain physical distancing,” Dr. Theresa Tam said.

“This pandemic is reaching us a lot about being flexible and adapting to new challenges.”

Canada’s new wording around aerosols is very similar to that of the World Health Organization, which first recognized aerosol transmission in July.

The U.S. Centers for Disease Control issued similar guidance in October, although it emphasized at the time that it still believes prolonged, close contact with an infected person is a much more significant source of COVID-19 spread.