Canada COVID-19

2022 - 4 - 25

Impact of population mixing between vaccinated and unvaccinated ... (CMAJ)

Nonvaccination is expected to result in amplification of disease transmission in unvaccinated subpopulations, but the communicable nature of infectious diseases ...

Increased mixing between vaccinated and unvaccinated groups increased final epidemic size among vaccinated people; conversely, more like-with-like mixing decreased final epidemic size among vaccinated people but resulted in enhancement of the degree to which risk among vaccinated people could be attributed to unvaccinated people. Using simple mathematical modelling, we have shown that, although risk associated with avoiding vaccination during a virulent pandemic accrues chiefly to those who are unvaccinated, the choice of some individuals to refuse vaccination is likely to affect the health and safety of vaccinated people in a manner disproportionate to the fraction of unvaccinated people in the population. As like-with-like mixing increased, contribution to infection risk among vaccinated people was increasingly derived from (less and less common) interactions with unvaccinated people, increasing the value of ψ. We found similar patterns in sensitivity analyses in which vaccine coverage was increased from 80% to 99% ( Figure 3). Increasing population vaccination coverage decreased the attack rate among vaccinated people (as expected, owing to indirect protective effects) but further increased the relative contribution to risk in vaccinated people by those who were unvaccinated at any level of like-with-like mixing. However, we find that the degree to which people differentially interact with others who are like themselves is likely to have an important impact on disease dynamics and on risk in people who choose to get vaccinated. The value of ψ would increase above 1 either because of an increased fraction of infections derived from contact with unvaccinated people or a decrease in the amount of contact between the groups (i.e., an increase in like-with-like mixing). For example, with random mixing, peak incidence was simultaneous in the vaccinated and unvaccinated groups, but with strong like-with-like mixing the epidemic peak among vaccinated people occurred about 1 week later than among unvaccinated people; population-adjusted peak incidence was 4 times higher in the unvaccinated population than in the vaccinated population with random mixing, but about 30 times higher with strong like-with-like mixing ( Figure 1). For our model, with 20% of the population unvaccinated, when random mixing is assumed (η = 0), 20% of the contacts a vaccinated person has would be expected to occur with unvaccinated people. We calculated a quantity (ψ), which we defined as the fraction of all infections among vaccinated people that derived from contact with unvaccinated people, divided by the fraction of all contacts that occurred with unvaccinated people. We sought to contrast contribution to epidemic size and risk estimates by subpopulation, and to understand the impact of mixing between vaccinated and unvaccinated groups on expected disease dynamics. In our model, like-with-like mixing is determined by a constant (η), with random mixing occurring when η = 0, complete like-with-like mixing occurring when η = 1 and intermediate degrees of like-with-like mixing occurring at intermediate values. 13, 24, 25 To better understand the implications of the interplay between vaccinated and unvaccinated populations under different assumptions about population mixing, we constructed a simple susceptible–infectious–recovered model to reproduce the dynamics of interactions between vaccinated and unvaccinated subpopulations in a predominantly vaccinated population. The contact-adjusted contribution of unvaccinated people to infection risk was disproportionate, with unvaccinated people contributing to infections among those who were vaccinated at a rate higher than would have been expected based on contact numbers alone.

Canada's Covid-19 Entry Rules Are Changing (Again) Today (Forbes)

Fully vaccinated travelers have seen rules soften, but be aware that mask mandates remain in place throughout much of Canada.

Children under five are also not required to provide a negative Covid-19 test upon entry. Since April 1, vaccinated travelers have not had to provide pre-arrival testing results, but the ArriveCan app was still asking for a detailed 14-day quarantine plan in case travelers tested positive on the random arrival test. As of today, fully vaccinated travelers are no longer required to provide a quarantine plan to isolate if they test positive. As in the U.S., each Canadian province and city has its own rules about mask wearing, and many provinces still have mandates in place. The two most important changes apply to vaccinated adults and unvaccinated children. Everyone who enters Canada must still download the ArriveCAN app and complete the questionnaire within 72 hours of arrival.

'Individual responsibility is not gone': B.C. disease expert on ... (Globalnews.ca)

Pre-entry COVID-19 tests are required for partially vaccinated or unvaccinated travellers ages 12 and older who are currently eligible to travel to Canada, ...

This is what is going to make us survive the spring and survive the summer, is if we all realize that COVID is not gone and there’s still work to do.” Again, there are no provincial mandates, this does not mean that individual responsibility in the era of COVID is gone. So I think that any easing with COVID still around will eventually lead to an increase in transmission.”

Today's coronavirus news: Federal government calls inquiry into use ... (Toronto Star)

Meanwhile, Beijing districts were placed under lockdown as COVID cases in the Chinese capital mount.

More than a dozen businesses shuttered over the past two years, and while the pandemic has taken a toll on big-name fashion stores, so too has changing tastes, changing shopping habits and the new nature of the neighbourhood, which is experiencing a boom of new residential skyscrapers in the area. Construction paper is haphazardly taped to the entrances of what used to be the flagship stores of some of the world’s largest fashion brands. Health care settings, however, remain some of the last places in Illinois where everyone must continue to cover their mouths and noses. Health officials say 128 people were admitted to hospital in the past 24 hours and 127 people left. The number of people in intensive care dropped by four, to 86. The sewage data is the earliest sign of future virus cases in the community. “I think that we may be starting to turn the corner on this most recent small wave of infections,” said Davidson Hamer, a Boston University School of Public Health infectious diseases specialist. I feel more accessible and I feel like the media has the ability to ask the questions they need to. 6:03 p.m. or much of the past two years, America has been first in line for COVID-19 vaccines and treatments. It requested an additional $22.5 billion for what it called “urgent” needs in both the U.S. and abroad. The search for portfolio buffers in the U.S. is evident in the highest relative cost of loss-protecting put contracts in two years. Most of Beijing is being tested for the virus, subduing sentiment by fanning fears of an unprecedented lockdown in the city.

COVID-19 update for April 25: Mixing with unvaccinated increases ... (Vancouver Sun)

Here's your daily update with everything you need to know on the coronavirus situation in B.C. and around the world.

Those without symptoms do not need a test. You can find a testing centre using the B.C. Centre for Disease Control’s testing centre map. Visitors to seniors’ homes are also required to take a rapid antigen test before visiting the facility or be tested on arrival. As case counts began to explode in early 2020, doctors could not explain the growing number of kidney injuries resulting from a virus that primarily attacks cells in the respiratory tract. “We entered late 2021 with a situation where the vast majority of Canadians had vaccine-induced immunity, and only a very small proportion who had been infected,” he said. Where is the country at with COVID? “In a way we’re kind of in this weird place. Article content We’ll provide summaries of what’s going on right here so you can get the latest news at a glance. U.S. approves COVID drug for young children Back to video COVID-19 update for April 25: Mixing with unvaccinated increases risk Article content Article content

COVID-19 Update: New research on 'natural immunity' | Tourism ... (Calgary Herald)

Because Alberta no longer conducts widespread PCR testing, actual case counts are estimated to be higher. Graph shows 7-day moving average in Alberta's five ...

Still, visitor numbers are down about 44 per cent from the April 15-17, 2019 period. As Canada heads into its peak summer holiday season, tour operators are betting the revival seen in the first week of April would gather pace. This is in addition to the parliamentary committee, which will hear from Public Safety Minister Marco Mendicino and Justice Minister David Lametti Tuesday night. Where is the country at with COVID? “In a way we’re kind of in this weird place. “Heritage Park is such an important part of Calgary to be able to talk about and immerse yourself into the history of Western Canada.” Article content Article content Ottawa invests $6M into research on youth Back to video COVID-19 Update: New research on 'natural immunity' Article content Ottawa invests $6M into research on youth COVID-19 Update: New research on 'natural immunity'

Here's how Canada's new COVID-19 travel rules could affect your ... (Daily Hive)

On Friday, the federal government announced further relaxed pandemic border measures for returning travellers. Beginning 1 pm ET/4 pm PT today, children aged ...

“Although some restrictions may be easing, air and rail travellers are reminded that they are still required to wear a mask throughout their travel journey.” The rule wasn’t very well known, and it’s unclear how many people followed it. In addition, the country is scrapping its rule that people who’ve returned from abroad must wear masks in indoor public spaces for 14 days following their trip.

What you need to know about COVID-19 in Ottawa for the week of ... (CBC.ca)

Here's CBC Ottawa's latest roundup of key updates during the coronavirus pandemic.

Anyone who's interested in a PCR test or vaccine can call 613-967-3603, rapid tests are available at the wellbeing centre on weekdays. Ontario expanded eligibility in mid-April to groups including everyone age 70 and over. Nineteen residents have died between its north and south sections and about 2,000 residents had tested positive until April 2022, when its northern section stopped sharing a total. The Mohawks of the Bay of Quinte are keeping mask mandates for government buildings until May 2. Testing strategies have changed under the contagious Omicron variant and many people with COVID-19 aren't reflected in case counts. They have to start within a certain period of developing symptoms. Akwesasne has COVID-19, test and vaccine information online or at 613-575-2341. The U.S. requires all adults crossing a border to be fully vaccinated. People can also buy them. Recent wastewater data from sites in the Kingston area is stable or dropping from high levels. Some places may choose to continue requiring people wear masks, be vaccinated or both. If you have severe symptoms, call 911.

Canada's updated border restrictions: What you need to know (CTV News)

Certain travellers will now have an easier time entering Canada as the country relaxes more of the border measures initially put in place to curb the spread ...

The City of Calgary has launched an online solar calculator. If you're under 60, you can get a fourth dose. 6 hr ago Experts say dangerous warning signs are missed in parents who could harm or kill their child. 6 hr ago All travellers are also still expected to use the ArriveCAN app or webpage to submit necessary travel information, including their proof of vaccination. “Right now, of course within the Canadian context, Omicron BA.2 is going strong… Those travelling from abroad also won’t be required to keep a list of close contacts and places visited for the first 14 days after their arrival in Canada. Those with a valid medical contraindication to COVID-19 vaccines won’t be required to provide a quarantine plan when entering Canada either. Children under the age of five won’t be required to complete a pre-entry COVID-19 test either, and are exempt for vaccination requirements. This is according to an announcement made by the Public Health Agency of Canada on April 22. International travellers will also notice updated requirements on providing a quarantine plan following their arrival in Canada.

Quebec reports eight more COVID-19 deaths as hospitalizations ... (Toronto Star)

MONTREAL - COVID-19 hospitalizations in Quebec continued to show signs of stabilizing on Monday, as the province reported a one-patient rise in the nu...

The number of people in intensive care dropped by four, to 86. Last week, officials said there were at least 200 new daily admissions in hospital between Tuesday and Friday, when they reported a sixth-wave high of 2,410 COVID-19 hospitalizations. Health officials said there were 2,345 patients in hospital with COVID-19 after 128 people were admitted in the past 24 hours and 127 people left.

COVID-19 in Quebec: What you need to know Monday | CBC News (CBC.ca)

The federal government is easing some measures aimed at international travellers. Quebec is extending masking in public places until mid-May.

- Loss of appetite. - Fatigue. *The new cases are those reported to the Quebec government only. - Headache. - Fever. - Difficulty breathing.

Mixing with unvaccinated increases COVID-19 risk for vaccinated ... (Toronto Star)

MONTREAL - While remaining unvaccinated against COVID-19 is often framed as a personal choice, those who spurn the vaccines raise the risk of infectio...

He said the arrival of more contagious COVID-19 variants, such as Omicron, have impacted both vaccine effectiveness and public faith in vaccination. Fisman said that in real life, people tend to spend the most time with people who are similar to them. The researchers used a mathematical model to estimate how many infections would occur in a population, depending on how much mixing occurred between vaccinated and unvaccinated people.

COVID infections driving up Winnipeg emergency wait times, WRHA ... (CBC.ca)

A rise in COVID-19 infections in Winnipeg is driving up wait times for hospital emergency and urgent care departments, says the head of Winnipeg Health ...

He said changes are being made to reduce wait times. She said a number of factors have contributed to the issue facing Winnipeg hospitals. She suggested hospitals are responsible for coming up with ideas to reduce wait times. "COVID is continuing to spread throughout the community. As a result, they are requiring more and longer medical care." This is driving up wait times at emergency departments and urgent care wards to what he described as "concerning" levels, particularly for patients who are less sick, he said in the email.

Canada COVID-19

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