mask, the difference between life and death

A new discovery by scientists suggests that, depending on how infected a person is, they will be asymptomatic, moderately ill, or severely ill.

“Dose makes poison ”is the maxim attributed to Paracelsus, a Swiss physician-philosopher since the beginning of the Renaissance. This means that any substance can be poisonous if administered in a sufficiently high concentration. Too much water can also wash off your electrolytes and can be fatal.

Seeing the coronavirus through this lens – which “dose” of virus you receive will make the difference between being asymptomatic, moderately ill or severely ill – can be helpful when thinking about protection against Covid-19 now, when temperatures drop and the number of cases increases.

SARS-CoV-2 likely behaves like other viruses

The concept that a certain dose of a pathogen – a pathogen – is required to generate an infection has been demonstrated in many viruses, such as influenza, chicken pox and others, explains Erin Bromage, associate professor of biology at the university. of Massachusetts. Dartmouth. “If you target an animal with a low enough dose, it will be able to resist without getting sick at all. But with a high dose of pathogens, an infection sets in and the animal gives in. So the dose becomes really important.”

It doesn’t take a certain number of viral particles to infect a cell – this only increases the chances of one of these particles entering the cell and infecting it, triggering the chain reaction.

Another approach is like conception: you don’t need millions of sperm to fertilize an egg – one is enough, but men produce millions to increase the chances of someone reaching the egg, piercing its protection and fertilizing.

A single viral or time-spreading dose

There is another dimension to viral dose and it has to do with time. It is not just the virus dose received at a time that matters, but also the sum of the viral doses over a period of time. “Some people speculate on this: Why are bus drivers or emergency personnel likely more vulnerable, for example? Because they are exposed to higher doses or because they are in an environment where they are exposed for a long time and receive a wider range. ? Asks Bromage.

In mid-October, the US Centers for Disease Control and Prevention (CDC) changed the definition of “close contact” to include shorter exposures totaling 15 minutes or more with an infected person.

Not only the virus is important, but the host as well

“There is a certain dangerous dose of the virus for everyone,” says Bromage. “For an immunocompromised or stressed person, less exposure to the virus than a healthy person can lead to similar results.”

The risk of infection depends on the physiology of the potential host as well as personal health habits and habits such as smoking, diet, physical activity and sleep. The worst case scenario is an elderly and sick person with long and repeated exposures. A medically vulnerable person may receive a low dose of the virus; on the contrary, a healthy person can be overwhelmed by a high dose.

A tragic example is the death of the young and apparently healthy Dr. Li Wenliang in Wuhan. On December 30, 2019, he sounded the alarm after seeing seven cases of SARS-like disease in hospital patients; four days later, he was accused by police of “seriously disrupting social order” and “spreading rumors online”. Shortly after treating his critically ill patients, Li developed symptoms of Covid-19; he died less than a month later. He was only 34 years old.

We’re still just talking about probabilities and probabilities. Pointing out the exact scenario leading to infection is much more difficult.

“We can’t study the exact viral dose that can make someone sick because it’s unethical,” says Dr. Monica Gandhi, an infectious disease physician and professor at the University of California, San Francisco (UCSF). This would mean exposing people to progressive doses of the virus to determine when infection occurs.

“I don’t think we’ll really know a value. We can have animals – there are ferret and hamster models – where you give more to the patient, it’s useful and can give us information. But unfortunately, we won’t know enough about people.”

Viral dose and viral load

“It’s an interesting dance of two sides of a coin between the dose – what’s going on – and the viral load – what’s going on,” Gandhi says. Viral pregnancy is the amount of virus in the body of an infected person; some studies, not all, have shown that the sicker a patient is with Covid-19, the higher the viral load.

“If you take a lower dose of the virus, you can calmly treat it and isolate it. You have an asymptomatic infection and are less likely to produce a high viral load, so it’s related to a milder disease,” he says. He noted that in places where universal use of a mask has been adopted – such as an Argentine cruise ship and several U.S. food processing plants – the rate of asymptomatic infections, over 80 percent, was more than double. . Rate it. the general rate of 40% per annum. that the CDC has estimated. The mask appears to reduce the dose by filtering out the viral particles.

The connection between masks and vaccines

There is, however, another fascinating and important way to think about virus dosage. If the dose is low enough, it may not cause disease, but it can also generate a vaccine-like immune response. It is an extraordinary concept of crucial importance.

In fact, Gandhi and his co-author, Dr. George Rutherford of the Department of Epidemiology and Biostatistics at UCSF, published an article in the New England Journal of Medicine in September claiming that wearing a mask, an exposed person would receive a less dose. virus that without a mask – preventing disease, but triggering the response of the body’s immune system.

In the article, they compared “chickenpox,” as a similar process was called, when people were deliberately exposed to low doses of the virus from a sick person to create immunity. This happened before the vaccine was introduced. “I gave them a little virus and they were a little sick, then they developed an immune response – and it worked perfectly.”

It could also explain why some people never have the symptoms of Covid-19 but still have antibodies to the virus. But more research will be needed to confirm this.

Because people can’t control unless we talk about how much they get from a viral dose, Gandhi reiterated what almost all health experts have said we should do to be as safe as possible: keep our physical distance. compared to those outside the home, choose outdoor and non-indoor spaces, have good hand hygiene and – please – mask upstairs! (November 2, CNN)

Source: hotnews.ro