The “dose” of coronavirus that a person receives may determine how ill they are.Masks may help

SARS-CoV-2 may behave like any other virus

The notion that a specific dose of pathogen (the cause of the disease) is needed to cause an infection has been shown to apply to many viruses, including influenza and poxviruses, said Associate Erin Bromaji. Explained Professor of Biology at the University of Massachusetts Dartmouth.

“If you hit an animal at a low enough dose, they can dodge it without developing any disease. Once you get the magical number of infections, the infection is established and the animal succumbs. It’s a disease caused by that particular pathogen, but when infected in excess of the infection, in most cases high doses of the pathogen (for example, high doses of the virus) lead to more serious consequences, which is really important. ” He called the relationship “dose-dependent.”

It is not because a certain number of virus particles are needed to infect cells. One of the viral particles is more likely to invade and infect cells, causing a chain reaction.

From another point of view, it’s like conception. You don’t need millions of sperms to fertilize an egg. Only one is needed, but men make millions of sperms that increase their chances of reaching an egg and overcome their defenses. And fertilize it.

Take the dose of the virus at once or spread over time

There is another aspect of virus dosage, which is time-related. What matters is not the amount of virus that is readily available at any given time. It may also be the sum of the viral loads acquired over a particular period of time.

“Some people speculate about it. For example, bus drivers and people working in emergency rooms have worse results because they are exposed to higher doses or because they are in the environment. Why are they likely to bring about? Are they exposed to it over a long period of time and put a larger band of it inside them? “Bromage asked.

It’s not just about viruses, it’s about hosts

The virus itself is not the only organism that plays a role-it also has to do with individuals.

“Each person needs a different amount of virus,” Bromage said. “For example, people who are immunosuppressed or stressed need less. [virus] Challenge yourself to get the same results as someone in good health. ”

All in all, the likelihood of infection depends on the physiology of the potential host, as well as personal behavior and health habits such as smoking, diet, physical activity, and sleep. Elderly or unhealthy hosts facing large-scale recurrent exposure are clearly the worst scenarios. However, medically vulnerable people can get sick even at low doses of the virus. Conversely, healthy people can be overwhelmed at high enough doses.

Still, we’re just talking about odds and possibilities. Identifying the exact scenario that leads to infection is much more difficult.

“It’s completely unethical, so we can’t study the exact viral load that makes someone sick,” said Dr. Monica Gandhi, an infectious disease doctor and professor of medicine at the University of California, San Francisco. This is because it means deliberately exposing people to high doses of the virus to determine when the infection will occur.

“I don’t think we’ll actually reach that value. It’s possible with animals. There are ferret and hamster models. Currently, with two animal models, the more you give, the more you get sick. It helps when it comes in, and it may give us meaning, but unfortunately humans don’t know how long it will take, “she said.

Viral load and viral load

“There is an interesting double-sided dance of coins that comes out during the virus [dose] -What goes in-and viral load-what comes out, “Gandhi said. The viral load is the amount of virus that an infected person has in his body. Some, but not all, studies have shown that patients are ill. Covid-19 has a high viral load.

“If the viral load is low, you can calmly treat and close the wall. This asymptomatic infection is less likely to be viral. The viral load is low, so it is less severe. It is not related to the disease. ”

She has more than 80% asymptomatic infection rates at more than twice the estimated asymptomatic infections of the CDC in places and situations where universal masking is used, such as on Argentine cruise ships and several US food processing plants. I said there is. Percentage of about 40%. The mask appears to reduce the dose by filtering some of the virus particles.

Relationship between mask and vaccine

However, there is another attractive and important way to think about the administration of the virus. If the dose is low enough, it may not cause illness, but it can cause an immune response, similar to a vaccine. This is a very important concept to note.

In her article, she and Rutherford described “variolation,” a similar process called when people were deliberately exposed to smallpox substances from sick people to create immunity. I drew a comparison. This was before the introduction of the smallpox vaccine.

“We’re going to give them just a little virus, and they’ll get a little sick and then they’ll develop an immune response-and it worked perfectly,” she said. It was.

It may also help explain why some people never develop the symptoms of Covid-19, but still have antibodies to the virus. However, further investigation is needed to confirm that.

Gandhi says almost all public health professionals should be as safe as possible because people have no control over how much they take, let alone the dose of the virus. I repeated that. Choose an outdoor space over indoors, practice hand hygiene, and wear a mask.