As Canada hit some dismal coronavirus pandemic milestones — surpassing 30,000 cases and 1,300 deaths — Manitoba reached a positive turning point.

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As Canada hit some dismal coronavirus pandemic milestones — surpassing 30,000 cases and 1,300 deaths — Manitoba reached a positive turning point.

For the first time, the province registered more people recovered from COVID-19 than active cases.

On Friday, chief provincial public health officer Dr. Brent Roussin reported no new cases of the virus, with 132 patients who've recovered and 113 active cases.

"We should be cautiously optimistic," Roussin said, warning Manitoba is six weeks behind other hard-hit provinces and it is "too soon to let up our guard."

The R0 (pronounced R-naught) is a virus’s basic reproductive number — an epidemiologic metric used to describe the contagiousness of infectious agents. It's a theoretical number based on the average number of people who would be infected by a single case in a susceptible population, said Roussin.

The R0 rate for COVID-19 is estimated around 2.5 or 2.6, he said: for social-distancing measures to be lifted in Manitoba, it needs to decrease to below one.

 

How a virus can spread and quickly

overwhelm the health-care system

Exponential growth from the reproduction number (R0) of 2

Those two people

each infect another

two people

Infected by a pathogen

with an R0 of 2, one

individual infects

two people

Each of those people infect two more.

 

The virus continues to spread exponentially and the infected population quickly overwhelms the health-care system

The reproduction number (R0) of a virus describes how many new cases of the disease that a single infected person can cause.

 

The basic R0, depicted here, demonstrates the maximum potential spread of the virus.

 

An effective R0 is dependant on how infectious the pathogen is and the

population’s susceptibility.

 

An individual’s overall health, any existing immunity and vacinations can greatly influence the effective R0. The physical environment and socioeconomics are also factored in the effective RO.

 

Measles, a highly infectious virus, has an RO in the range of 12-18. Polio and smallpox have an R0 of 5-7.

 

COVID-19 is estimated to have a basic R0 between 1.5 and 3.5 with 2.5 as the widely recognized value.

Winnipeg Free Press

 

How a virus can spread and quickly

overwhelm the health-care system

Exponential growth from the reproduction number (R0) of 2

Each of those people infect

two more.

 

The virus continues to spread exponentially and the infected population quickly overwhelms the health-care system

Infected by a pathogen

with an R0 of 2, one

individual infects

two people

Those two people

each infect another

two people

The reproduction number (R0) of a virus describes how many new cases of the disease that a single infected person can cause.

 

The basic R0, depicted here, demonstrates the maximum potential spread of the virus.

 

An effective R0 is dependant on how infectious the pathogen is and the

population’s susceptibility.

 

An individual’s overall health, any existing immunity and vacinations can greatly influence the effective R0. The physical environment and socioeconomics are also factored in the effective RO.

 

Measles, a highly infectious virus, has an RO in the range of 12-18. Polio and smallpox have an R0 of 5-7.

 

COVID-19 is estimated to have a basic R0 between 1.5 and 3.5 with 2.5 as the widely recognized value.

Winnipeg Free Press

 

How a virus can spread and quickly overwhelm the health-care system

Exponential growth from the reproduction number (R0) of 2

The reproduction number (R0) of a virus describes how many new cases of the disease that a single infected person can cause.

 

The basic R0, depicted here, demonstrates the maximum potential spread of the virus.

 

An effective R0 is dependant on how infectious the pathogen is and the

population’s susceptibility.

 

An individual’s overall health, any existing immunity and vacinations can greatly influence the effective R0. The physical environment and socioeconomics are also factored in the effective RO.

 

Measles, a highly infectious virus, has an RO in the range of 12-18. Polio and

smallpox have an R0 of 5-7.

 

COVID-19 is estimated to have a basic R0 between 1.5 and 3.5 with 2.5 as the widely recognized value.

Infected by a pathogen

with an R0 of 2, one

individual infects

two people

Those two people

each infect another

two people

Each of those

people infect

two more

The virus continues

to spread exponentially

and the infected population

quickly overwhelms the

health-care system

Winnipeg Free Press

There have been only 10 new cases in the last six days in Manitoba, but Roussin couldn't say if the low number or more strict public health orders have had an effect on COVID-19's reproductive rate.

"Its a tough thing to calculate," he said, adding the reproductive number will change as fewer people become susceptible to the virus over time.

Until then, public health orders remain, limiting travel to the north and ordering people returning to Manitoba to self-isolate for 14 days. Next week, the province will announce guidelines to stop health-care workers from working at more than one personal care home to limit the risk of transmitting the virus to elderly and vulnerable residents.

"All these measures we are taking here are to decrease the (R0) value to under one," said Roussin.

In Ottawa, the first chief public health officer of Canada said the reproductive rate is retrospective, and may not reflect Manitoba's low case numbers for two or three weeks.

"The number is calculated on previous numbers that eventually will get adjusted to reflect the current level of transmission," said Dr. David Butler-Jones, who held the national post from 2004-14. "You're always looking backwards. There's no way of knowing what today's rate is."

"All these measures we are taking here are to decrease the (R0) value to under one." – Dr. Brent Roussin, Manitoba's chief provincial public health officer

Two or three weeks from now, after more people have been tested, Manitoba may have the reproductive rate of the virus drop if the number of positive test results remains low, said Butler-Jones.

However, all the gains made from social distancing can rapidly disappear, he warned.

"The R0 can change very quickly, if you're not careful," he said. "All you need is a nursing home outbreak... or what happened in Newfoundland... that totally skews the numbers."

A person who attended a March 16 funeral in St. John's has been linked to at least 143 COVID-19 cases in that province.

"All you need is one super-shedder," Butler-Jones said.

The reproductive rate for a virus varies, with some diseases much more transmissible than the novel coronavirus, said University of Manitoba virologist Jason Kindrachuk.

Seasonal influenza has a reproductive rate between one and two, on average; measles is one of the most transmissible diseases, with one person infecting between 12 and 18 people, said Kindrachuk.

carol.sanders@freepress.mb.ca

Carol Sanders

Carol Sanders
Legislature reporter

After 20 years of reporting on the growing diversity of people calling Manitoba home, Carol moved to the legislature bureau in early 2020.

   Read full biography