Health officials in the United States this week cut COVID-19 isolation restrictions for asymptomatic Americans from 10 to five days, leading some Canadians to wonder whether similar recommendations could be adopted here.
The Centers for Disease Control and Prevention said its new guidance is in keeping with evidence that people with COVID-19 are most infectious in the two days before and three days after symptoms develop.
While some experts say the move is necessary to curb strain on hospitals as more and more staff become infected or exposed to the highly transmissible Omicron variant, others argue the approach is flawed, and “fraught with danger.”
“If somebody tested positive and a few days later … you had to sit next to them on the subway, how would you feel?” said Raywat Deonandan, an epidemiologist with the University of Ottawa.
“A certain number of days is not sufficient (when) we’re looking for indication of non-infectious status.”
Dr. Zain Chagla, an infectious disease expert with McMaster University, said the CDC guidance is meant to avoid “secondary consequences” of having large numbers of essential workers isolating for 10 days.
Halving recommendations for isolation and quarantine isn’t the perfect solution, Chagla said, noting the infectious period with COVID-19 “is not set in stone.” But the move is realistic, he added.
“The reality of the situation is we have to be a little bit pragmatic about what’s coming and the number of people that will be infected or exposed to COVID-19,” he said.
How likely is Canada to adopt similar guidelines?
The Public Health Agency of Canada said in an email Wednesday it was aware of the new CDC guidance, adding it would “inform Canadians should there be an update to (Canada’s) recommendations in the future.”
Quebec said Tuesday certain health workers who have tested positive for COVID-19 will be allowed to stay on the job — on a case-by-case basis — a move the province said is necessary to keep the health-care system operational.
Alberta Premier Jason Kenney said Tuesday there was no immediate plan to follow Quebec’s decision.
Manitoba said Monday it may consider similar recommendations if there is further strain on its health system while Ontario said it’s also contemplating shortening isolation and quarantine.
Cynthia Carr, an epidemiologist in Winnipeg, said whatever guidance provinces adopt should focus on symptoms rather than the calendar to determine when to drop isolation measures.
“You don’t just lock in on the five days, you lock in on how you’re feeling,” she said. “If you have any symptoms at all that is absolutely the most important factor, even if guidelines were to change in Canada.”
What’s the science behind the CDC guidelines?
The CDC website says the change is “motivated by science” of when transmission is most likely to occur.
The reduced isolation is meant only for those who are asymptomatic after five days, the agency says, adding it should also be followed by five days of wearing a mask in public.
Deonandan said the guidance is based on pre-Omicron data, however, and the contagious period of the new variant could differ from previous strains. The window of contagiousness will also vary from person to person, he added.
“That’s worrying,” Deonandan said. “It’s entirely possible that many cases will not be experiencing the average number of days of infectiousness.”
Carr said it’s still unknown whether the period of infectiousness changes with Omicron, but a person’s own degree of contagiousness depends on factors including their immune system.
She added the incubation period with Omicron — the time between infection and symptom-onset — appears to be shorter than previous strains.
“That would stand to reason that your infectious period is very close to the point at which you are infected,” she said.
How do you know if you’re no longer contagious?
Deonandan said one of the biggest flaws with the CDC’s guidelines is that it doesn’t require a negative test at the five-day mark, adding the best way to determine whether the virus is still present and potentially transmissible is through repeated testing.
But what if you don’t have access to multiple tests?
During times when supply is low, Deonandan said rapid tests may need to be reserved for health-care workers to ensure they can safely return to work after an infection.
Carr said the CDC’s argument for shortened isolation stems from their data, which suggests 85 to 90 per cent of transmission happens in that five-day time period. But since asymptomatic people can’t be sure they’ve cleared the virus without a test, they should still rely on risk-mitigation strategies, including wearing a tight-fitting mask in public.
Those who have symptoms at the five-day mark shouldn’t end their isolation, she added.
What do you do if you think you have COVID-19?
Securing a timely appointment for a PCR test is becoming more difficult with many jurisdictions reaching testing capacity, and health experts warn daily case counts are likely much higher than what’s being reported.
Health Canada’s website says people should contact their “local health authority” for advice about testing if they think they have COVID-19 or have been exposed to someone who recently tested positive.
Some provinces are starting to rely more heavily on rapid tests to help alleviate strain on testing centres.
Manitoba this week said it would make take-home, self-administered rapid tests available at provincial testing sites and only ask people to return for a PCR if their take-home test is positive.
Is Omicron producing a more mild illness?
Early research suggests omicron may cause milder illnesses than earlier versions of the virus. But the sheer number of people becoming infected threatens to crush hospital capacity, experts say.
Carr said early data on Omicron stemmed from cases in mostly younger populations who weren’t at risk for hospitalization, and more data is needed before scientists can definitively say the variant is less severe.
She noted that even a 40 to 60 per cent reduction in hospitalization with Omicron could be negated by the sheer transmissibility of the variant.
“The reduction in risk might not be enough to account for the escalation in cases,” Carr said.
— With files from The Associated Press
Melissa Couto Zuber, The Canadian Press
Over 1.2 million people died from drug-resistant infections in 2019 – study
More than 1.2 million people died in 2019 from infections caused by bacteria resistant to multiple antibiotics, higher than HIV/AIDS or malaria, according to a new report published on Thursday.
Global health officials have repeatedly warned about the rise of drug-resistant bacteria and other microbes due to the misuse and overuse of antibiotics, which encourages microorganisms to evolve into “superbugs”.
The new Global Research on Antimicrobial Resistance report, published in The Lancet, revealed that antimicrobial resistance (AMR) was directly responsible for an estimated 1.27 million deaths and associated with about 4.95 million deaths. The study analysed data from 204 countries and territories.
“These new data reveal the true scale of antimicrobial resistance worldwide… Previous estimates had predicted 10 million annual deaths from AMR by 2050, but we now know for certain that we are already far closer to that figure than we thought,” said Chris Murray, co-author of the study and a professor at the University of Washington.
Last year, the World Health Organization warned that none of the 43 antibiotics in development or recently approved medicines were enough to combat antimicrobial resistance.
Cornelius Clancy, professor of Medicine at the University of Pittsburgh, said one of the ways to tackle AMR is to look at a new treatment model.
“The traditional antibiotic model that we’ve had for past number of decades since penicillin. I think it is tapped out.”
Most of 2019’s deaths were caused by drug resistance in lower respiratory infections such as pneumonia, followed by bloodstream infections and intra-abdominal infections.
AMR’s impact is now most severe in Sub-Saharan Africa and South Asia, while around one in five deaths is in children aged under five years.
There was limited availability of data for some regions, particularly many low and middle-income countries, which may restrict the accuracy of the study’s estimates.
Clancy said the focus has been on COVID-19 for the past two years, but AMR is a “long-term kind of challenge”.
(Reporting by Mrinalika Roy in Bengaluru; Editing by Krishna Chandra Eluri and Devika Syamnath)
Study casts doubt on reliability of rapid antigen tests in kids; COVID transmission through breastmilk unlikely
The following is a summary of some recent studies on COVID-19. They include research that warrants further study to corroborate the findings and that has yet to be certified by peer review.
Rapid antigen tests may be unreliable in children
When used in children, rapid antigen tests for detecting the coronavirus do not meet accuracy criteria set by the World Health Organization and U.S. and UK device regulators, according to researchers who reviewed 17 studies of the tests.
The trials evaluated six brands of tests in more than 6,300 children and teenagers through May 2021. In all but one study, the tests were administered by trained workers. Overall, compared to PCR tests, the antigen tests failed to detect the virus in 36% of infected children, the researchers reported on Tuesday in BMJ Evidence-Based Medicine. Among children with symptoms, it missed 28% of infections. Among infected kids without symptoms, the tests missed the virus in 44%. Only about 1% of the time did the tests mistakenly diagnose the virus in a child who was not actually infected.
Given that more than 500 antigen tests are available in Europe alone, the authors said, “the performance of most antigen tests under real-life conditions remains unknown.” But the new findings “cast doubt on the effectiveness” of rapid antigen tests for widespread testing in schools, they concluded.
Breastmilk transmission of COVID-19 unlikely
A new study appears to confirm smaller, earlier studies that suggested nursing mothers are unlikely to transmit the coronavirus in breastmilk.
Between March and September 2020, researchers obtained multiple breastmilk samples from 110 lactating women, including 65 with positive COVID-19 tests, 36 with symptoms who had not been tested, and a control group of 9 women with negative COVID-19 tests. Seven women (6%) – six with positive tests and one who had not been tested – had non-infectious genetic material (RNA) from the virus in their breastmilk, but none of the samples had any evidence of active virus, according to a report published on Wednesday in Pediatric Research. Why breastmilk would contain coronavirus RNA but not infectious virus is unclear, said study leader Dr. Paul Krogstad of the David Geffen School of Medicine at UCLA, “Breastmilk is known to contain protective factors against infection, including antibodies that reflect both the mother’s exposure to viruses and other infectious agents and to vaccines she has received,” he noted.
The U.S. Centers for Disease Control and Prevention (CDC) advises that before breastfeeding, bottle-feeding, or expressing milk, women with COVID-19 should wash their hands or use hand sanitizer with at least 60% alcohol. The CDC also recommends that they wear a mask when within 6 feet (1.8 meters) of the baby.
New technique may speed vaccine, antibody drug development
Researchers are working on a way to speed development of vaccines and monoclonal antibody drugs for COVID-19 and other illnesses, shortening the time from collection of volunteers’ blood samples to identification of potentially useful antibodies from months to weeks.
As described in Science Advances on Wednesday, the new technique employs cryo-electron microscopy, or cryoEM, which involves freezing the biological sample to view it with the least possible distortion. Currently, “generation of monoclonal antibodies involves several steps, is expensive, and typically takes somewhere on the order of two to three months, and at the end of that process you still need to perform structural analysis of the antibodies” to figure out where they attach themselves to their target, and how they actually work, explained Andrew Ward of Scripps Research Institute in La Jolla, California.
In experiments using the new approach to look for antibodies to HIV, “we flipped the process on its head… by starting with structure,” Ward said. Because cryoEM affords such high resolution, instead of having to laboriously sort through antibody-producing immune cells one by one to identify promising antibodies, the process of identifying antibodies, mapping their structure and seeing how they are likely to attack viruses and other targets goes much faster, he added. “The ongoing COVID-19 pandemic has highlighted the need for such robust and rapid technologies,” his team concluded.
Click for a Reuters graphic on vaccines in development.
(Reporting by Nancy Lapid; Editing by Bill Berkrot)
Vaccination plus infection offered most protection during Delta surge, U.S. study shows – CBC News
Protection against the previously-dominant Delta variant was highest among people who were both vaccinated and had survived a previous COVID-19 infection, according to a report published Wednesday by the U.S. Centers for Disease Control and Prevention (CDC).
The report also found those who had previously been infected with COVID-19 were better protected against the Delta variant than those who were vaccinated alone, suggesting that natural immunity was a more potent shield than vaccines against that variant, California and New York health officials reported on Wednesday.
Protection against Delta was lowest among those who had never been infected or vaccinated, the CDC report continued.
“The evidence in this report does not change our vaccination recommendations,” Dr. Ben Silk of the CDC and one of the study’s authors told a media briefing.
“We know that vaccination is still the safest way to protect yourself against COVID-19,” he said.
The findings do not apply to the Omicron variant of the virus, which now accounts for 99.5 per cent of COVID-19 cases in the United States.
Study includes data from May to November
For the study, health officials in California and New York gathered data from May through November, which included the period when the Delta variant was dominant.
It showed that people who survived a previous infection had lower rates of COVID-19 than people who were vaccinated alone.
That represented a change from the period when the Alpha variant was dominant, Silk told the briefing.
“Before the Delta variant, COVID-19 vaccination resulted in better protection against a subsequent infection than surviving a previous infection,” he said.
In the summer and fall of 2021, however, when Delta became the predominant circulating iteration of the virus in the United States, “surviving a previous infection now provided greater protection against the subsequent infection than vaccination,” he said.
But acquiring immunity through natural infection carries significant risks. According to the study, by Nov. 30, 2021, roughly 130,781 residents of California and New York had died from COVID-19.
The analysis did not include information on the severity of initial infection, nor does it account for the full range of illness caused by prior infection.
One important limitation to the study was that it ended before administration of vaccine booster doses was widespread.
WATCH | Experts agree the science behind booster shots is sound:
‘Clearly shows’ vaccines provide safest protection
Dr. Erica Pan, state epidemiologist for the California Department of Public Health, said in an email that the study “clearly shows” that vaccines provide the safest protection against COVID-19 and they offer added protection for those with prior infections.
“Outside of this study, recent data on the highly contagious Omicron variant shows that getting a booster provides significant additional protection against infection, hospitalization and death,” Pan said.
Silk said the CDC is studying the impact of vaccination, boosters and prior infection during the Omicron surge and expects to issue further reports when that data becomes available.
So far, Omicron has proven to evade some level of immunity from both vaccination and previous infection, but vaccines are still largely preventing serious illness and death.
An Israeli hospital on Monday also said preliminary research indicates a fourth dose of leading mRNA-based vaccines provides only limited defence against infection from the variant.
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