As many as four million Ontarians may have been infected with the Omicron variant, according to the province’s science advisers, but their illnesses alone – particularly the milder ones – may not stop them from getting reinfected.
“The hope was that Omicron rips through the population, doesn’t render a lot of suffering, and leaves behind the gift of immunity,” he said.
“That is now in question. But it might be possible that if you get reinfected multiple times, maybe then you’ll get something resembling … durable immunity. It’s too early to know. Signs are not pointing in a positive direction.”
A recent preprint study – one that has not been peer-reviewed – suggested that mild Omicron infection doesn’t render enough immunity to prevent future infections, while infections from the Delta variant, which tended to be more severe, produced higher protection.
Fahad Razak, an internist and member of Ontario’s science advisory table, said the province is not seeing “significant” numbers right now of people with more than one Omicron infection.
But milder illnesses that give people congestion, cough, fever, and leave them feeling unwell but not so sick that they need to go to the hospital – like many Omicron infections – may leave people more susceptible to reinfection, he said.
“The parts of your immune system that protect against those milder infections, they tend to wane much faster than the parts of your immune system that protect against the more severe infection,” Dr. Razak said.
Omicron probably provides some short-term protection from reinfection, but there may not be long-term protection, said University of Toronto immunology professor Tania Watts. The combination of vaccination and infection is much better, she said.
“One thing our vaccines do is they give us what we call systemic immunity, because you inject it in the muscle, and the antibodies circulate around our body,” she said.
But the reason that immunity starts to wane is that people need those antibodies in the nose and throat, where the virus enters, she said.
“So when you get an infection, after two doses of vaccine, it can actually pull that immune response rapidly into the nose, and it leaves behind cells and those tissues that will respond again,” Prof. Watts said.
People who received two doses of a COVID-19 vaccine and then got Omicron will “almost certainly” see an immunity boost, she said, but that may not hold true for unvaccinated people who get Omicron.
Kieran Moore, Ontario’s chief medical officer of health, said getting vaccinated plus receiving an mRNA booster dose “significantly” adds to people’s level and length of protection against Omicron, but for unvaccinated people who get infected their immunity may not last as long.
“It appears with Omicron, if you get natural immunity – so you’re not vaccinated and you get infected by Omicron – you do have some immunity against further reinfection,” Dr. Moore said.
“But there is significantly a risk for reinfection from Omicron over time. So we’re not confident in how long that duration of immunity is from natural exposure yet. It’s still early days.”
Available figures from Public Health Ontario show there have been 3,208 confirmed cases of COVID-19 reinfections since Nov. 1, 2020, although the data don’t indicate what strain of the virus individuals were infected with.
Case numbers since late December – after Omicron became dominant – are likely an undercount, since the province has limited access to PCR testing, and therefore genomic sequencing, since then.
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First reported case of a person getting COVID from a cat – Nature.com
First there were sneezing hamsters, now sneezing cats. A team in Thailand reports the first solid evidence of a pet cat infecting a person with SARS-CoV-2 — adding felines to the list of animals that can transmit the virus to people.
Researchers say the results are convincing. They are surprised that it has taken this long to establish that transmission can occur, given the scale of the pandemic, the virus’s ability to jump between animal species, and the close contact between cats and people. “We’ve known this was a possibility for two years,” says Angela Bosco-Lauth, an infectious-disease researcher at Colorado State University in Fort Collins.
Studies early in the pandemic found that cats shed infectious virus particles and can infect other cats. And over the course of the pandemic, countries have reported SARS-CoV-2 infections in dozens of pet cats. But establishing the direction of viral spread — from cat to person or from person to cat — is tricky. The Thai study “is an interesting case report, and a great example of what good contact tracing can do”, says Marion Koopmans, a virologist at the Erasmus University Medical Center in Rotterdam, the Netherlands.
The feline finding, published in Emerging Infectious Diseases1 on 6 June, came about by accident, says co-author Sarunyou Chusri, an infectious-disease researcher and physician at Prince of Songkla University in Hat Yai, southern Thailand. In August, a father and son who had tested positive for SARS-CoV-2 were transferred to an isolation ward at the university’s hospital. Their ten-year-old cat was also swabbed and tested positive. While being swabbed, the cat sneezed in the face of a veterinary surgeon, who was wearing a mask and gloves but no eye protection.
Three days later, the vet developed a fever, sniffles and a cough, and later tested positive for SARS-CoV-2, but none of her close contacts developed COVID-19, suggesting that she had been infected by the cat. Genetic analysis also confirmed that the vet was infected with the same variant as the cat and its owners, and the viral genomic sequences were identical.
Researchers say that such cases of cat-to-human transmission are probably rare. Experimental studies have shown that infected cats don’t shed much virus, and shed for only a few days, says Leo Poon, a virologist at the University of Hong Kong.
Still, Chusri says it is worth taking extra precautions when handling cats suspected of being infected. People “should not abandon their cats, but take more care of them”, he says.
Other animals suspected of infecting people include farmed mink in Europe and North America, pet hamsters in Hong Kong and wild white-tailed deer in Canada. Adding cats to the list “expands our understanding of the zoonotic potential of this virus”, says Poon.
But researchers say these are all rare events and animals don’t yet play a significant part in spreading the virus. “Humans are clearly still the major source of the virus,” says Bosco-Lauth.
WHO warns of monkeypox risk to kids, pregnant people if spread continues – CBC News
The World Health Organization said “sustained transmission” of monkeypox worldwide could see the virus begin to move into high-risk groups, such as pregnant people, immunocompromised people and children.
WHO said on Wednesday it is investigating reports of infected children, including two cases in the United Kingdom, as well as following up reports in Spain and France. None of the cases in children have been severe.
The virus has now been identified in more than 50 new countries outside the countries in Africa where it is endemic. Cases are also rising in those countries, said WHO, calling for testing to be ramped up.
“I’m concerned about sustained transmission because it would suggest that the virus establishing itself and it could move into high risk groups including children, the immunocompromised and pregnant women,” said WHO chief Tedros Adhanom Ghebreyesus.
Sustained transmission is characterized by the World Health Organization as an illness that can transmit easily from one person to others in the population.
Monkeypox is usually mild, and is endemic in parts of western and central Africa. It is spread by close contact, so it is relatively easy to contain through measures such as self-isolation and hygiene.
There have been more than 3,400 cases of monkeypox and one death since the outbreak began in May, largely in Europe among men who have sex with men, according to a WHO tally. There have also been more than 1,500 cases and 66 deaths in countries this year where the disease more commonly spreads.
At least 275 cases of monkeypox have been confirmed in Canada. Those include 202 cases in Quebec, 67 cases in Ontario, four in Alberta and two in British Columbia.
The Public Health Agency of Canada (PHAC) declined to comment on WHO’s warning on Wednesday.
Health officials will likely face questions about Canada’s monkeypox response at a media conference scheduled for 11 a.m. ET on Thursday.
Not a global health emergency ‘at this stage’
WHO’s warning comes days after it said the global outbreak of the virus should be closely monitored, but does not warrant being declared a global health emergency.
In a statement Saturday, a WHO emergency committee said many aspects of the outbreak were “unusual” and acknowledged that monkeypox — which is endemic in some African countries — has been neglected for years.
“While a few members expressed differing views, the committee resolved by consensus to advise the WHO director general that at this stage the outbreak should be determined to not constitute” a global health emergency, WHO said in a statement.
WHO nevertheless pointed to the “emergency nature” of the outbreak and said controlling its spread requires an “intense” response.
The committee said the outbreak should be “closely monitored and reviewed after a few weeks.” But it said it would recommend a re-assessment before then if certain new developments emerge, such as cases among sex workers, spread to other countries or within countries that have already had cases, increased severity of cases or an increasing rate of spread.
The UN agency said it was also working on a mechanism to distribute vaccines more equitably, after countries including Britain and the United States suggested they were willing to share their stockpiled smallpox vaccines, which also protect against monkeypox.
Heart Attack Drug Proves Effective at Treating Stroke – Technology Networks
In the largest stroke clinical trial ever run in Canada, researchers have shown Tenecteplase (TNK), a safe, well tolerated drug, commonly used as a clot buster for heart attacks, is an effective treatment for acute ischemic stroke. Led by researchers with the University of Calgary at the Foothills Medical Centre and Sunnybrook Health Sciences Centre, fully affiliated with the University of Toronto, the study included 1600 patients at hospitals throughout Canada.
“It is truly an important finding that I share with my colleagues from coast to coast. Through this collaboration these findings could revolutionize stroke treatment throughout the world,” says Dr. Bijoy Menon, MD, professor at the University of Calgary, neurologist at the Foothills Medical Centre and co-principal investigator on the study. “Tenecteplase is known to be an effective clot dissolving drug. It is very easy to administer which makes it a game changer when seconds count to save brain cells,”
Based on current guidelines, Alteplase (tPA) is the recommended drug for acute ischemic stroke patients. The challenge is that the drug is more complex to administer. It takes up to an hour and requires an infusion pump that needs to be monitored. The pump can be cumbersome when transporting a patient within a hospital, or to a major stroke center for treatment.
“One of the reasons Tenecteplase is so effective is that in can be administered as a single immediate dose,” says Dr. Rick Swartz, MD, PhD, clinician-researcher at the University of Toronto, co-principal investigator, and stroke neurologist at Sunnybrook Health Sciences Centre. “That’s a big advantage, saving critical time and complication. TNK could potentially be administered wherever the patient is seen first, at a medical centre or small hospital,”
The AcT Trial compared TNK to tPA in a randomized trial. The results published in The Lancet show that TNK worked as well as, if not better than, the current recommended drug, tPA. TNK attaches itself to the clot for a longer period of time than tPA which means that blood flow is restored faster and for a longer period of time. Along with discovering a better way to treat acute ischemic stroke, the team also established a more cost effective, and efficient way to conduct clinical trials.
Reference: Menon BK, Buck BH, Singh N, et al. Intravenous tenecteplase compared with alteplase for acute ischaemic stroke in Canada (AcT): a pragmatic, multicentre, open-label, registry-linked, randomised, controlled, non-inferiority trial. The Lancet. 2022;0(0). doi: 10.1016/S0140-6736(22)01054-6
This article has been republished from the following materials. Note: material may have been edited for length and content. For further information, please contact the cited source.
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