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Can COVID-19 vaccines reduce transmission? Here’s what we know so far – Global News

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If you have received the coveted coronavirus vaccine shot, there is both good and bad news.

While there is a high probability you will not get sick with COVID-19, there is a chance you can still catch the novel coronavirus and in turn infect others.

Read more:
So you got a COVID-19 shot. Now what can you do?

“Vaccination doesn’t prove that you are immune,” said Alberto Martin, professor of immunology at the University of Toronto.

Canada has so far approved four different coronavirus vaccines. During the global clinical trials, the shots from Pfizer, Moderna, AstraZeneca and Johnson & Johnson showed high efficacy rates – ranging from 62 per cent to 95 per cent – in preventing moderate to severe COVID-19 illness.

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But there are still many unanswered questions about whether the vaccines can also suppress transmission – that is, keep vaccinated people from acquiring the virus and spreading it to others.

There are a number of ongoing studies looking at the effectiveness of the vaccines on transmission – and preliminary data is promising.


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Ipsos poll finds 69% would take COVID-19 vaccination without hesitation


Ipsos poll finds 69% would take COVID-19 vaccination without hesitation

According to a pre-print analysis in The Lancet medical journal – not yet peer-reviewed – the AstraZeneca-Oxford vaccine was shown to reduce the rate of positive PCR tests by half when two doses were given. There was a 67 per cent reduction after one dose.

A study by Cambridge University in the U.K. suggests that a single dose of the Pfizer-BioNTech vaccine can reduce fourfold the number of asymptomatic COVID-19 infections. These results released on Feb. 26 are yet to be peer-reviewed.

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Read more:
How long will the COVID-19 vaccine protect you?

Meanwhile, another Israeli study published in the Lancet medical journal on Feb. 18 found an 85 per cent reduction in symptomatic COVID-19 infections within 15 to 28 days of receiving a first dose of the Pfizer vaccine, with an overall reduction in infections, including asymptomatic cases detected by testing, of 75 per cent.

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These are encouraging signs for ending the pandemic, as preventing infection in those who have been vaccinated means there is no virus that can be passed on to others.

If you never get infected, then it’s also possible that you won’t transmit it to other people,” said Gerald Evans, an infectious disease specialist at Queen’s University in Kingston, Ont.

Pfizer is currently testing a subset of Phase 3 trial participants to look for evidence of symptomatic and asymptomatic infection.

“Understanding whether the vaccine can stop the transmission of the virus will be an important tool for the continued rollout of the vaccine and to inform public health planning efforts and recommendations,” Christina Antoniou, director of corporate affairs of Pfizer Canada, told Global News in an emailed statement.

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According to the World Health Organization (WHO), there is limited evidence about the performance of the COVID-19 vaccines to prevent infection or transmission.

However, it is “reasonable to assume there will be some level of protection against transmission,” the U.N. health agency said in an emailed statement to Global News.

Evans said while more data is needed to determine the vaccination’s impact in real-world settings, he believes vaccines are the “number one tool” at our disposal and will substantially curb COVID-19 spread.

I’m estimating about 75 to 80 per cent reduction in transmission,” he said.

“That’s the way we’re going to be able to go into a post-pandemic world.”


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Easing of restrictions due to vaccinations not happening soon


Easing of restrictions due to vaccinations not happening soon

Martin is also confident that vaccines will stop the spread of COVID-19 or any other disease, for that matter.

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Once you establish immunity to a specific virus, you can no longer transmit it,” he said.

He explained that the immune memory established by the vaccine prevents the virus from producing billions of viral copies needed for a person to become infectious.

“So you yourself are protected and you protect others around you,” he said.

Read more:
Can delaying a second COVID-19 shot save lives? Some experts say so

There is also evidence that the viral load, which determines how much virus you can emit when you cough, breathe or sneeze, is significantly lower when you are vaccinated.

Results of a pre-print study done in Israel — not peer-reviewed — suggested that the Pfizer-BioNTech vaccine can reduce the viral load for infections by fourfold 12 to 28 days after the first dose is given.

“These reduced viral loads hint to lower infectiousness, further contributing to vaccine impact on virus spread,” the authors said.


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The Travel Lady: Will vaccination passports play a role in future travel?

Evans said this is important because high viral loads are not just associated with more severe disease but also with a higher risk of transmission.

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“If the infection you get is associated with a really low viral load, then that means the likelihood that you’re going to go on to transmit it to somebody else is significantly and dramatically reduced.”

— with files from Global News’ Linda Boyle 

© 2021 Global News, a division of Corus Entertainment Inc.

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CANADA STOCKS – TSX falls 0.14% to 19,201.28

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* The Toronto Stock Exchange’s TSX falls 0.14 percent to 19,201.28

* Leading the index were Stantec Inc <STN.TO​>, up 3.4%, Imperial Oil Ltd​, up 3.3%, and Corus Entertainment Inc​, higher by 2.9%.

* Lagging shares were Aphria Inc​​, down 14.2%, Village Farms International Inc​, down 9.9%, and Aurora Cannabis Inc​, lower by 9.4%.

* On the TSX 91 issues rose and 134 fell as a 0.7-to-1 ratio favored decliners. There were 24 new highs and no new lows, with total volume of 228.0 million shares.

* The most heavily traded shares by volume were Toronto-dominion Bank, Royal Bank Of Canada and Suncor Energy Inc.

* The TSX’s energy group fell 0.32 points, or 0.3%, while the financials sector climbed 2.46 points, or 0.7%.

* West Texas Intermediate crude futures rose 0.52%, or $0.31, to $59.63 a barrel. Brent crude  rose 0.4%, or $0.25, to $63.2 [O/R]

* The TSX is up 10.1% for the year.

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Air Canada signs C$5.9 billion government aid package, agrees to buy Airbus, Boeing jets

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By David Ljunggren and Allison Lampert

OTTAWA/MONTREAL (Reuters) -Air Canada, struggling with a collapse in traffic due to the COVID-19 pandemic, reached a deal on Monday on a long-awaited aid package with the federal government that would allow it to access up to C$5.9 billion ($4.69 billion) in funds.

The agreement – the largest individual coronavirus-related loan that Ottawa has arranged with a company – was announced after the airline industry criticized Prime Minister Justin Trudeau’s Liberal government for dawdling. The United States and France acted much more quickly to help major carriers.

Canada‘s largest carrier, which last year cut over half its workforce, or 20,000 jobs, and other airlines have been negotiating with the government for months on a coronavirus aid package.

In February, Air Canada reported a net loss for 2020 of C$4.65 billion, compared with a 2019 profit of C$1.48 billion.

As part of the deal, Air Canada agreed to ban share buybacks and dividends, cap annual compensation for senior executives at C$1 million a year and preserve jobs at the current level, which is 14,859.

It will also proceed with planned purchases of 33 Airbus SE 220 airliners and 40 Boeing Co 737 MAX airliners.

Chris Murray, managing director, equity research at ATB Capital Markets, said the deal took into account the “specific needs of Air Canada in the short and medium term without being overly onerous.”

He added: “It gives them some flexibility in drawing down additional liquidity as needed.”

Transport Minister Omar Alghabra said the government was still in negotiations with other airlines about possible aid.

Canada, the world’s second-largest nation by area, depends heavily on civil aviation to keep remote communities connected.

Opposition politicians fretted that further delays in announcing aid could result in permanent damage to the country.

Air Canada said it would resume services on nearly all of the routes it had suspended because of COVID-19.

‘SIGNIFICANT LAYER OF INSURANCE’

The deal removes a potential political challenge for the Liberals, who insiders say are set to trigger an election later this year.

The government has agreed to buy C$500 million worth of shares in the airline, at C$23.1793 each, or a 14.2% discount to Monday’s close, a roughly 6% stake.

“Maintaining a competitive airline sector and good jobs is crucially important,” Finance Minister Chrystia Freeland told reporters, adding the equity stake would allow taxpayers to benefit when the airline’s fortunes recovered.

The Canadian government previously approved similar loans for four other companies worth up to C$1.billion, including up to C$375 million to low-cost airline Sunwing Vacations Inc. The government has paid out C$73.47 billion under its wage subsidy program and C$46.11 billion in loans to hard-hit small businesses.

Michael Rousseau, Air Canada‘s president and chief executive officer, said the liquidity “provides a significant layer of insurance for Air Canada.”

Jerry Dias, head of the Unifor private-sector union, described the announcement as “a good deal for everybody.”

Unifor represents more than 16,000 members working in the air transportation sector.

But the Canadian Union of Public Employees, which represents roughly 10,000 Air Canada flight attendants, said the package protected the jobs of current workers rather than the 7,500 members of its union who had been let go by the carrier.

($1=1.2567 Canadian dollars)

(Reporting by David Ljunggren in Ottawa and Allison Lampert in Montreal; Additional reporting by Julie Gordon in Ottawa and Munsif Vengattil in Bengaluru; Editing by Dan Grebler and Peter Cooney)

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U.K. advises limiting AstraZeneca in under-30s amid clot worry

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LONDON —
British authorities recommended Wednesday that the AstraZeneca COVID-19 vaccine not be given to adults under 30 where possible because of strengthening evidence that the shot may be linked to rare blood clots.

The recommendation came as regulators both in the United Kingdom and the European Union emphasized that the benefits of receiving the vaccine continue to outweigh the risks for most people — even though the European Medicines Agency said it had found a “possible link” between the shot and the rare clots. British authorities recommended that people under 30 be offered alternatives to AstraZeneca. But the EMA advised no such age restrictions, leaving it up to its member-countries to decide whether to limit its use.

Several countries have already imposed limits on who can receive the vaccine, and any restrictions are closely watched since the vaccine, which is cheaper and easier to store than many others, is critical to global immunization campaigns and is a pillar of the UN-backed program known as COVAX that aims to get vaccines to some of the world’s poorest countries.

“This is a course correction, there’s no question about that,” Jonathan Van-Tam, England’s deputy chief medical officer, said during a press briefing. “But it is, in a sense, in medicine quite normal for physicians to alter their preferences for how patients are treated over time.”

Van-Tam said the effect on Britain’s vaccination timetable — one of the speediest in the world — should be “zero or negligible,” assuming the National Health Service receives expected deliveries of other vaccines, including those produced by Pfizer and Moderna.

EU and U.K. regulators held simultaneous press conferences Wednesday afternoon to announce the results of investigations into reports of blood clots that sparked concern about the rollout of the AstraZeneca vaccine.

The EU agency described the clots as “very rare” side effects. Dr Sabine Straus, chair of EMA’s Safety Committee, said the best data is coming from Germany where there is one report of the rare clots for every 100,000 doses given, although she noted far fewer reports in the U.K. Still, that’s less than the clot risk that healthy women face from birth control pills, noted another expert, Dr. Peter Arlett.

The agency said most of the cases reported have occurred in women under 60 within two weeks of vaccination — but based on the currently available evidence, it was not able to identify specific risk factors. Experts reviewed several dozen cases that came mainly from Europe and the U.K., where around 25 million people have received the AstraZeneca vaccine.

“The reported cases of unusual blood clotting following vaccination with the AstraZeneca vaccine should be listed as possible side effects of the vaccine,” said Emer Cooke, the agency’s executive director. “The risk of mortality from COVID is much greater than the risk of mortality from these side effects.”

Arlett said there is no information suggesting an increased risk from the other major COVID-19 vaccines.

The EMA’s investigation focused on unusual types of blood clots that are occurring along with low blood platelets. One rare clot type appears in multiple blood vessels and the other in veins that drain blood from the brain.

While the benefits of the vaccine still outweigh the risks, that assessment is “more finely balanced” among younger people who are less likely to become seriously ill with COVID-19, the U.K’s Van-Tam said.

“We are not advising a stop to any vaccination for any individual in any age group,” said Wei Shen Lim, who chairs Britain’s Joint Committee on Vaccination and Immunization. “We are advising a preference for one vaccine over another vaccine for a particular age group, really out of the utmost caution rather than because we have any serious safety concerns.”

In March, more than a dozen countries, mostly in Europe, suspended their use of AstraZeneca over the blood clot issue. Most restarted — some with age restrictions — after the EMA said countries should continue using the potentially life-saving vaccine.

Britain, which relies heavily on AstraZeneca, however, continued to use it.

The suspensions were seen as particularly damaging for AstraZeneca because they came after repeated missteps in how the company reported data on the vaccine’s effectiveness and concerns over how well its shot worked in older people. That has led to frequently changing advice in some countries on who can take the vaccine, raising worries that AstraZeneca’s credibility could be permanently damaged, spurring more vaccine hesitancy and prolonging the pandemic.

Dr. Peter English, who formerly chaired the British Medical Association’s Public Health Medicine Committee, said the back-and-forth over the AstraZeneca vaccine globally could have serious consequences.

“We can’t afford not to use this vaccine if we are going to end the pandemic,” he said.

In some countries, authorities have already noted hesitance toward the AstraZeneca shot.

“People come and they are reluctant to take the AstraZeneca vaccine, they ask us if we also use anything else,” said Florentina Nastase, a doctor and co-ordinator at a vaccination centre in Bucharest, Romania. “There were cases in which people (scheduled for the AstraZeneca) didn’t show up, there were cases when people came to the centre and saw that we use only AstraZeneca and refused (to be inoculated).”

Meanwhile, the governor of Italy’s northern Veneto region had said earlier Wednesday that any decision to change the guidance on AstraZeneca would cause major disruptions to immunizations — at a time when Europe is already struggling to ramp them up — and could create more confusion about the shot.

“If they do like Germany, and allow Astra Zeneca only to people over 65, that would be absurd. Before it was only for people under 55. Put yourself in the place of citizens, it is hard to understand anything,” Luca Zaia told reporters.

The latest suspension of AstraZeneca came in Spain’s Castilla y Leon region, where health chief Veronica Casado said Wednesday that “the principle of prudence” drove her to put a temporary hold on the vaccine that she still backed as being both effective and necessary.

French health authorities had said they, too, were awaiting EMA’s conclusions, as were some officials in Asia.

On Wednesday, South Korea said it would temporarily suspend the use of AstraZeneca’s vaccine in people 60 and younger. In that age group, the country is only currently vaccinating health workers and people in long-term care settings.

The Korea Disease Control and Prevention Agency said it would also pause a vaccine rollout to school nurses and teachers that was to begin on Thursday, while awaiting the outcome of the EMA’s review.

But some experts urged perspective. Prof Anthony Harnden, the deputy chair of Britain’s vaccination committee, said that the program has saved at least 6,000 lives in the first three months and will help pave the way back to normal life.

“What is clear it that for the vast majority of people the benefits of the Oxford AZ vaccine far outweigh any extremely small risk,” he said. “And the Oxford AZ vaccine will continue to save many from suffering the devastating effects that can result from a COVID infection.”

Source: – CTV News

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