adplus-dvertising
Connect with us

Health

Asymptomatic COVID-19 findings dim hopes for 'herd immunity' and 'immunity passports' – CBC.ca

Published

 on


A closer look at people who tested positive for COVID-19 but never developed symptoms has found that such asymptomatic carriers have few to no detectable antibodies just weeks after infection, suggesting they may not develop lasting immunity.

There’s growing evidence that a significant proportion of people who test positive for COVID-19 never show symptoms, although it’s not clear what percentage of people that is and what role they play in spreading the disease.

A Chinese study published this week in Nature followed 37 people in Wanzhou District in China who did not show any outward signs of the disease, despite testing positive when their respiratory tracts were swabbed and being kept in hospital for observation.

300x250x1

Some key findings include:

  • Levels of antibodies against COVID-19 were significantly lower in asymptomatic carriers than those with symptoms during active infection.

  • Antibody levels also dropped off far more quickly in people who never showed symptoms, and 40 per cent of them had no detectable antibodies eight weeks after recovery, compared with 13 per cent of symptomatic patients.

  • Those with asymptomatic infections tested positive for an average of five days longer than people with symptomatic infections — 19 days compared with 14 days — suggesting that they were shedding the virus longer.

Unlike nasal swab tests that can only detect an active infection, antibody tests can detect previous infections. But a new study suggests antibodies often don’t stick around for long after an infection. (Zuleika Chan)

The study also found that despite having no outward symptoms, 70 per cent had lung abnormalities detectable in X-rays at some point during infection — mostly spots called “ground-glass opacities,” which can indicate inflammation or other signs of disease.

No antibodies could mean no immunity, but not necessarily

Dr. Samir Gupta, a clinician-scientist at St. Michael’s Hospital in Toronto and assistant professor of medicine at the University of Toronto, noted in an interview with CBC News Network earlier this week that the study was very small.

Gupta, who wasn’t involved in the study, added that it wasn’t surprising that antibody levels fell a few months after infection. He said that’s normal, since it’s energy intensive for the body to maintain antibodies it doesn’t need.

What was “a little bit surprising,” he said, was the fact that 40 per cent of people with asymptomatic infections had no detectable antibodies at all.

WATCH | Dr. Samir Gupta on Alberta’s testing plans:

Dr. Samir Gupta says Alberta’s testing may help to understand how far the coronavirus spread but he’s doubtful we’ve reached herd immunity. 8:35

However, Gupta said, people have immunity to coronaviruses that cause common colds for only a few months, and that may also be the case for the coronavirus that causes COVID-19.

On the other hand, he said, “antibodies aren’t the whole story.”

There are other components of the immune system that play a role, such as memory cells. They remember a pathogen and begin releasing antibodies when they encounter it again, but they are hard to detect, Gupta said.

What this means for herd immunity and vaccines

Still, Tania Watts, a professor of immunology at the University of Toronto who was not involved in the study, expressed concern about the implications.

“This suggests that natural infection may not give long-lasting immunity, which is what people have been worried about,” she said.

Some countries such as Sweden and at least one Canadian province have previously suggested that one way to control the spread of COVID-19 is to allow most of the population to get infected in a controlled fashion to generate “herd immunity.” Once the population reaches a certain threshold of previous infection, there won’t be enough susceptible people to spread the virus, and it can’t spread exponentially as an epidemic.

A patient receives a shot in the first-stage safety study clinical trial of a potential vaccine for COVID-19 in March. A vaccine will need to produce a strong and long-lasting immune response, something that natural infection may not always do. (Ted S. Warren/The Associated Press)

But Watts said the low and short-lived levels of antibodies in asymptomatic infections in this study suggest we can’t rely on herd immunity being induced for long enough a period of time to have an impact.

That means we may need to wait for a vaccine that induces a stronger, longer-lived response than many natural infections, she said. “I think this puts even more pressure on vaccine development.”

What this means for antibody tests, ‘immunity passports’

Watts said another implication of the study is that serological (blood) or antibody tests — which have been touted as a way to get an idea of who has been previously infected, how much of the population that represents and how close that is to herd immunity — may not work as hoped.

And it throws cold water on the idea of controversial “immunity passports,” the idea of allowing more social interactions, such as work, travel and mass gatherings, for people who have previously been infected and therefore are immune and can’t spread the virus — which would be based on serological testing. 

“Until we know what part of the immune system is protective,” Watts said, “it’s difficult to be able to do a test and tell someone you’re safe or not.”

What this means for disease transmission

While it’s known that presymptomatic people can transmit COVID-19, it’s not really known whether people who remain asymptomatic through the course of the disease can.

Watts said she thinks the finding in this study that people without symptoms shed the virus longer than people with symptoms is “shocking” and suggests we need to worry about transmission from asymptomatic people.

“Until we have a vaccine, I think we should have very clear recommendations that everybody wears masks.”

She said the longer period of viral shedding is probably because a lack of symptoms indicate a weaker immune response, resulting in a longer time to clear the infection.

On the other hand, too intense an immune response is what puts patients in the ICU struggling to breathe.

The ideal is somewhere in between and what we’d like in a vaccine, Watts said.

“We really need that Goldilocks immune response.”

Let’s block ads! (Why?)

728x90x4

Source link

Continue Reading

Health

Measles case reported locally turns out to be negative: health unit

Published

 on

NEWS RELEASE
SIMCOE MUSKOKA DISTRICT HEALTH UNIT
*************************
On March 26, the Simcoe Muskoka District Health Unit (SMDHU) was notified by Public Health Ontario’s (PHO) laboratory that due to laboratory error, the case of measles that had been lab-confirmed positive on March 12, based on symptoms and a positive urine measles laboratory result by PHO’s laboratory, is in fact negative for the measles virus.

“With this new information of the negative lab result, we believe that that individual was not infected with measles and that there has not been any public exposure to measles resulting from this individual’s illness,” said Dr. Charles Gardner, medical officer of health. “We recognize that notifying the public of what we believed to be a positive measles case in our area created worry, anxiety and disruption for some, and we regret this.

“We do know that, despite best efforts, on rare occasions laboratory errors can occur. We are working closely with the PHO’s laboratory to do all that we can to ensure that such an incident does not occur again.”

Measles is a highly contagious viral infection that spreads very easily through airborne transmission. The measles virus can live in the air or on surfaces for up to two hours.

300x250x1

Symptoms of measles begin seven to 21 days after exposure and include fever, runny nose, cough, drowsiness, and red eyes. Small white spots appear on the inside of the mouth and throat but are not always present. Three to seven days after symptoms begin, a red, blotchy rash appears on the face and then progresses down the body.

The risk of transmission to those vaccinated with two doses is low, and when it does occur tends to show a reduction in the severity of these symptoms.

“Although we are relieved for the individual involved, and for all Simcoe-Muskoka residents, that this case has now been confirmed as negative, we know that measles is still active in Ontario at this time and the potential remains for new cases to arise, especially given the increase in Ontarians travelling to areas in the world that have higher numbers of measles cases,” said Dr. Gardner. “This is why we continue to advise individuals to keep up to date with their routine immunizations, including measles, mumps and rubella (MMR) vaccination.”

The risk of measles is low for people who have been fully immunized with two doses of measles vaccine or those born before 1970; however, many children have been delayed in receiving their routine childhood immunizations and people who have not had two doses of measles vaccine are at higher risk of contracting the disease.

People who do get sick usually recover without treatment, but measles can be more severe for infants, pregnant women, and those with compromised immune systems. Possible complications include middle-ear infections, pneumonia, diarrhea, or encephalitis (swelling of the brain) and occasionally death in the very young. Even individuals who are up to date with the measles vaccine should watch for symptoms of measles for 21 days after exposure.

For more information about measles, please visit smdhu.org or call Health Connection at 705-721-7520 or 1-877-721-7520, Monday to Friday between 8:30 a.m. and 4:30 p.m. to speak with a public health professional.

*************************

Adblock test (Why?)

728x90x4

Source link

Continue Reading

Health

Kate Middleton Not Alone. Cancer On Rise For People Under 50, Say Experts

Published

 on

<!–

–>

Kate Middleton revealed on Friday that her cancer was discovered after she received abdominal surgery

London:

300x250x1

When Catherine, Princess of Wales, revealed she was being treated for cancer last week, part of the shock was that an otherwise healthy 42-year-old has a disease that mostly plagues older people.

However, researchers have been increasingly sounding the alarm that more and more people under 50 are getting cancer — and no one knows why.

Across the world, the rate of under-50s diagnosed with 29 common cancers surged by nearly 80 percent between 1990 and 2019, a large study in BMJ Oncology found last year.

window._rrCode = window._rrCode || [];_rrCode.push(function() (function(v,d,o,ai)ai=d.createElement(“script”);ai.defer=true;ai.async=true;ai.src=v.location.protocol+o;d.head.appendChild(ai);)(window, document, “//a.vdo.ai/core/v-ndtv/vdo.ai.js”); );

The researchers predicted the number of new cancer cases among younger adults will rise another 30 percent by the end of this decade, with wealthy countries particularly affected.

The increase in cases — and soaring global population — means that the number of deaths among under 50s from cancer has risen by nearly 28 percent over the last 30 years.

This occurred even as the odds of people of all ages surviving cancer have roughly doubled over the last half century.

Shivan Sivakumar, a cancer researcher at the UK’s University of Birmingham, called it an “epidemic” of young adult cancer.

Since Kate Middleton revealed on Friday that her cancer was discovered after she received abdominal surgery earlier this year, Sivakumar and other doctors have spoken out about the uptick in younger cancer patients they have been seeing at their clinics.

While breast cancer remains the most common for people under 50, the researchers expressed particular concern about the rise of gastrointestinal cancers — such as of the colon, pancreas, liver and oesophagus — in younger adults.

Colon cancer is now the leading cause of cancer deaths in men under 50 in the United States, according to the American Cancer Society. For women, it is number two — behind only breast cancer.

One high profile case of colorectal cancer was “Black Panther” actor Chadwick Boseman, who died at the age of 43 in 2020.

Why is this happening?

“We just don’t have the evidence yet” to say exactly what is causing this rise, Sivakumar told AFP, adding it was likely a combination of factors.

Helen Coleman, a cancer epidemiology professor at Queen’s University Belfast who has studied early onset cancer in Northern Ireland, told AFP there were two potential explanations.

One is that people in their 40s were exposed to factors known to cause cancer — such tobacco smoke, alcohol or being obese — at an earlier age than previous generations.

She pointed out that the “obesity epidemic” did not start until the 1980s.

Sivakumar felt that at least part of the puzzle could be explained by obesity.

However, there is “another wave” of under-50 patients who are neither obese nor genetically predisposed still getting cancer, he emphasised, adding that this could not be put down to “statistical chance”.

The other theory, Coleman said, is that “something different” has been going on with her generation.

Fingers have been pointed out a range of possible culprits — including chemicals, new drugs and microplastics — but none have been proven.

Some have suggested that so-called ultra-processed foods could be to blame. “But there’s very little data to back any of that up,” Coleman said.

Another theory is that the food we eat could be changing our gut microbiome.

While there is nothing conclusive yet, Coleman said her own research suggested that cancer causes changes to the microbiome, not the other way around.

Anti-vaxx conspiracy theorists have even tried to blame Covid-19 vaccines.

This is easily disproven, because the rise in young adult cancer has taken place over decades, but the vaccines have only been around for a few years.

What can be done?

To address the rise in younger colorectal cancer, in 2021 the US lowered the recommended age for screening to 45. Other countries have yet to follow suit.

But the researchers hoped that Catherine’s experience would remind people at home that they should consult their doctor if they sense anything is wrong.

“People know their bodies really well,” Sivakumar said.

window._rrCode = window._rrCode || [];_rrCode.push(function(){ (function(d,t) var s=d.createElement(t); var s1=d.createElement(t); if (d.getElementById(‘jsw-init’)) return; s.setAttribute(‘id’,’jsw-init’); s.setAttribute(‘src’,’https://www.jiosaavn.com/embed/_s/embed.js?ver=’+Date.now()); s.onload=function()document.getElementById(‘jads’).style.display=’block’;s1.appendChild(d.createTextNode(‘JioSaavnEmbedWidget.init(a:”1″, q:”1″, embed_src:”https://www.jiosaavn.com/embed/playlist/85481065″,”dfp_medium” : “1”,partner_id: “ndtv”);’));d.body.appendChild(s1);; if (document.readyState === ‘complete’) d.body.appendChild(s); else if (document.readyState === ‘loading’) var interval = setInterval(function() if(document.readyState === ‘complete’) d.body.appendChild(s); clearInterval(interval); , 100); else window.onload = function() d.body.appendChild(s); ; )(document,’script’); });

“If you really feel that something isn’t right, don’t delay — just get yourself checked out.”

Adblock test (Why?)

728x90x4

Source link

Continue Reading

Health

Almost 3,000 students suspended in Waterloo Region over immunization issues

Published

 on

Close to 3,000 children attending elementary school across Waterloo Region were suspended from school on Wednesday morning for not having up-to-date immunization records.

The region says Waterloo Public Health suspended 2,969 students under the Immunization of School Pupils Act (ISPA).

For several months, the region has been campaigning for people to get their children’s vaccinations up to date, including sending letters home to parents on a couple of occasions, warning that students’ records needed to be up to date or they would be suspended.

300x250x1

It announced in January that 32,000 students did not have up-to-date records: 22,000 elementary students and 10,000 high school students.


The latest health and medical news
emailed to you every Sunday.

“We have made remarkable progress from the original 27,567 immunization notices we sent to parents in November and December 2023,” Dr. Hsiu-Li Wang, medical officer of health, stated.

“Since that time, we have resolved more than 24,500 outdated vaccination records, providing students with valuable protection against these serious and preventable diseases.”

The high school students still have a few weeks to get their records up to date or else face suspension.

The ISPA requires students to have proof-of-vaccination records for diphtheria, polio, tetanus, pertussis, measles, mumps, rubella, varicella (chickenpox) and meningitis, which must be on file with public health.

Public health says caregivers whose children are suspended will need to book an appointment at regionofwaterloo.ca/vaccines for clinics, which will be held in Cambridge and Waterloo on weekdays.

“Given the high number of suspensions, it may take several days before you can be seen at an appointment and return your child to school,” a release from the region warns.

“Record submission and questions must be done in person to ensure immediate resolution.”

The last time suspensions over immunizations were issued was in 2019, when 1,032 students were suspended.

Adblock test (Why?)

728x90x4

Source link

Continue Reading

Trending