Friday, November 12, 2021

Dying of COVID or with it? Pathologists take on conspiracy theorists

This is all very well but relies on all involved medical personnel as acting with complete propriety. Where an autopsy or a CT scan has been conducted there can be no doubt of the diagnosis.

But how often are autopsy or CT scan results available? In a busy emergency ward such procedures can easily be omitted. The cases of people dying in accidents who are said to be covid victims cast a particularly troublesome light upon the rigor of covid diagnoses. Are such diagnoses invariably accompanied by an autopsy or scan? It seems unlikely.

The authors below are talking about best practice but the issue is how often best practice is followed. There are good reasons to believe that it often is not

Conspiracy theorists claim doctors are inflating the pandemic’s death toll by putting COVID-19 on the death certificate of everyone who died with the virus. But – the theory goes – they didn’t die from COVID, they died with COVID.

But the head of pathology at the Victorian Institute of Forensic Medicine has autopsied dozens of patients with COVID-19.

And on her table, she says, the signs of the virus are clear. “Absolutely, it is very obvious. The post-mortem CT [scan] changes are striking. The appearances of their lungs in the autopsy rooms are striking.”

The claim that COVID-19 death counts are over-inflated has been a regular go-to for conspiracy theorists and lockdown opponents throughout the pandemic.

A diverse group has promoted the idea, including former US president Donald Trump.

The claims are standard boiler-plate for conspiracy theorists, who often rally around the belief that powerful people in society are trying to deceive the public for their own benefit, says Mathew Marques, who lectures in social psychology at La Trobe University.

“Rarely is there a new conspiracy theory that is surprising, when they all follow the same structure or pattern – lay beliefs about a secretive group of often powerful actors engaging in a malevolent plot against a society,” he says.

In hospitals, it is easy to work out if a person has died from COVID-19 – they wouldn’t be in an ICU ward on a ventilator otherwise. The Institute of Forensic Medicine handles harder cases: people who died suddenly in the community while they had COVID-19.

In many cases, like car accidents, the cause of death is obvious. In others, it requires a lot more work. The team runs a computerised tomography (CT) scan, and then if needed conducts an autopsy.

The most obvious signs a person has died from COVID-19 – not with it – are seen in the lungs, says forensic radiologist Dr Chris O’Donnell.

On a CT scan, the lungs are typically a dark black void – the scanner’s representation of space filled with oxygen.

In people who die of COVID-19, “that air is completely replaced by inflammatory tissue that fills up the air sacs and stops the exchange of oxygen,” says Dr O’Donnell.

“They struggle to breathe and even when they do get a breath in, none of the air they breathe can get into their blood because their lungs are blocked full of this inflammatory tissue. They die of lack of oxygen.”

In the disease’s early stages, the CT scan shows the lungs clouding over with inflammatory tissue. Radiologists refer to this as “ground glass”.

In late-stage disease, the virus has completely filled the lungs with inflammatory tissue. “We call that a white-out, when there’s no air in the lung,” Dr O’Donnell says.

These cases are clear-cut and are added to the pandemic’s official death toll. But when it is clear after autopsy that COVID-19 did not contribute to death, they are not added, Dr O’Donnell says.

“That’s our role: to look into these cases more thoroughly. We’re working to find the real truth, whether people have died of COVID or whether it’s something else.”


Duke, UNC scientists identify new antibody for COVID-19 and variants

Only in mice so far but very hopeful

A research collaboration between scientists at Duke University and the University of North Carolina at Chapel Hill has identified and tested an antibody that limits the severity of infections from a variety of coronaviruses, including those that cause COVID-19 as well as the original SARS illness.

The antibody was identified by a team at the Duke Human Vaccine Institute (DHVI) and tested in animal models at UNC Gillings School of Global Public Health. Researchers published their findings Nov. 2 in the journal Science Translational Medicine.

“This antibody has the potential to be a therapeutic for the current epidemic,” said co-senior author Barton Haynes, M.D., director of DHVI. “It could also be available for future outbreaks, if or when other coronaviruses jump from their natural animal hosts to humans.”

Haynes and colleagues at DHVI isolated the antibody by analyzing the blood from a patient who had been infected with the original SARS-CoV-1 virus, which caused the SARS outbreak in the early 2000s, and from a current COVID-19 patient.

They identified more than 1,700 antibodies, which the immune system produces to bind at specific sites on specific viruses to block the pathogen from infecting cells. When viruses mutate, many binding cites are altered or eliminated, leaving antibodies ineffectual. But there are often sites on the virus that remain unchanged despite mutations. The researchers focused on antibodies that target these sites because of their potential to be highly effective across different lineages of a virus.

Of the 1,700 antibodies from the two individuals, the Duke researchers found 50 antibodies that had the ability to bind to both the SARS-CoV-1 virus as well as SARS-CoV-2, which causes COVID-19.

Further analysis found that one of those cross-binding antibodies was especially potent – able to bind to a multitude of animal coronaviruses in addition to the two human-infecting pathogens.

“This antibody binds to the coronavirus at a location that is conserved across numerous mutations and variations,” Haynes said. “As a result, it can neutralize a wide range of coronaviruses.”

With the antibody isolated, the DHVI team turned to researchers at UNC who have expertise in animal coronaviruses. The UNC team, led by co-senior author Ralph S. Baric, Ph.D., professor of epidemiology and microbiology and immunology at UNC-Chapel Hill, tested it in mice to determine whether it could effectively block infections, or minimize the infections that occurred.

They found that it did both. When given before the animals were infected, the antibody protected mice against developing SARS, COVID-19 and its variants such as Delta, and many animal coronaviruses that have the potential to cause human pandemics.

“The findings provide a template for the rational design of universal vaccine strategies that are variant-proof and provide broad protection from known and emerging coronaviruses,” Baric said.

When given after infections, the antibody reduced severe lung symptoms compared to animals that were not treated with the antibody.

“The therapeutic activity even after mice were infected suggests that this could be a treatment deployed in the current pandemic, but also stockpiled to prevent the spread of a future outbreak or epidemic with a SARS-related virus,” said David Martinez, Ph.D., a post-doctoral researcher in the Department of Epidemiology at UNC Gillings School of Global Public Health.

“This antibody could be harnessed to prevent maybe SARS-CoV-3 or SARS-CoV-4,” Martinez said.

Journal article:


AstraZeneca’s new Covid treatment: what is it and how does it work?

Australia’s drugs regulator, the Therapeutic Goods Administration (TGA), has granted “provisional determination” to pharmaceutical company AstraZeneca for a long-acting antibody cocktail which has shown promise in preventing Covid-19 in adults.

Provisional determination is an early step in the drugs approval process and means AstraZeneca can now submit further data to the TGA from human trials about how the treatment works and its safety. Once the TGA has scrutinised the data, and if it is satisfied with it, it may grant Evusheld “provisional approval” for use in Australia in limited circumstances. Further data must be collected and given to the TGA even if this occurs.

This treatment consists of two laboratory-made antibodies, tixagevimab and cilgavimab. These antibodies bind to the spike protein of the virus, stopping the virus from entering the body’s cells and causing an infection.

Because each of the antibodies attach to different parts of the protein, using them in combination may be more effective than using either alone. It is also hoped this will offer good protection against variants, since the virus would have to mutate in multiple ways to escape both antibodies’ actions.

Evusheld is being considered for use as a Covid-19 preventive in Australians aged 18 years and older. In August, AstraZeneca released the results of a trial of the treatment involving 5,197 participants from the US, UK, Spain, France and Belgium who did not have Covid-19. Seventy-five per cent of participants had comorbidities, including medical conditions that often mean vaccination is weak or ineffective. Two-thirds of participants received Evusheld, and the rest were given a placebo.

The trial found Evusheld reduced the risk of developing symptomatic Covid-19 by 77% compared to the placebo. There were no cases of severe Covid-19 or related deaths in those given Evusheld. In the placebo group, there were three cases of severe Covid-19, which included two deaths.

The results now need to be replicated more widely in further trials, which is why regulators such as the TGA require AstraZeneca to submit ongoing data.

Is it a vaccine?

No. A vaccine trains the body’s immune system to respond to the virus if a person becomes infected in the future. Evusheld provides antibodies directly to the body via two intra-muscular injections administered consecutively. It immediately targets and neutralises the virus, preventing the virus from entering cells and causing an infection in the first place.

If approved, Evusheld will be the first long-acting antibody available for Covid-19 prevention in vulnerable populations who are unable to mount an adequate immune response to the virus from vaccination alone, for example people with cancer, and some elderly people.

Associate Prof Nada Hamad, a haematologist in Sydney, said Evusheld and similar treatments under development are designed to fill a gap left by vaccines, and by antibody treatments like Sotrovimab.

Sotrovimab is given to people already diagnosed with Covid-19 who are at high risk of developing severe disease. Sotrovimab needs to be administered early after someone is diagnosed to be effective.

“But Sotrovimab is very short-acting,” Hamad said. “It just lasts as we wait for the virus to dissipate. Once you get over the virus, the treatment doesn’t hang around in your body.

“Evusheld is a longer-acting antibody, and the hope is it will prevent the infection.”

Clinical trials to date show Evusheld may provide six to 12 months of protection from the virus. This is significantly shorter than vaccines. Even though the protection offered by vaccines does slowly wane over time, they are still effective at preventing severe disease, death and hospitalisation months down the track.

“Evusheld and similar treatments being examined should be seen as a major advancement in protecting the very vulnerable, but not a vaccine alternative,” Hamad said.

Evusheld also takes longer to administer, is more expensive, needs to be given by a trained doctor or nurse, and patients may need longer monitoring afterwards than the 15 minutes required for a vaccine. It is not something that can be quickly given in a pharmacy or hub, so it is not ideal for widespread, fast rollout, Hamad said.

Plus, further data from ongoing trials is still needed, while the efficacy and safety of the vaccines are now well known.

Evusheld has also shown promise in preventing severe disease when given early as a treatment to those infected with Covid-19, similar to Sotrovimab.




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