What research says about the amount of coronavirus you were initially exposed to

Does the initial amount of coronavirus you are exposed to matter?

Let us ask this question another way: Say that two similar people are exposed to different amounts of coronavirus particles. Is one of them probably sicker from the next COVID-19 disease than the other?

If you were a scientist, how would you study this?

What you want to do is carry out an experiment with a whole bunch of people, and expose some to small amounts of the coronavirus, some to medium amounts, and some to high amounts, without them or the doctors knowing who to prevent. bias. Then you should check in regularly. You would see which groups are sick, and follow who died.

The problem is that doing this experiment is clearly immoral. So we should instead do our best by studying this subject in other ways.

We can start by looking at similar diseases. Believe it or not, we actually did that challenging study that I described above with H1N1 on a small number of people – another indication that H1N1 is significantly safer than the coronavirus. And researchers found that, yes, giving patients more disease meant they were more likely to have symptoms and more likely to be contagious.

Of course, the research that is not ethical for humans is often done on animals. In a paper published by the Infectious Diseases Society of America, hamsters were given COVID-19, then placed in a cage. A second group of healthy hamsters was placed in a cage next to them, with a fan blowing air from the infected hamsters to the healthy hamsters. Not surprisingly, 66% of healthy hamsters became infected.

The study then compared what happened when a standard surgical mask was placed in the cage. Only 25% of the healthy hamsters were infected.

But that’s not all. The infected hamsters in the cages blocked by a mask were less sick than those who were originally infected in essence in every way: Fewer of their cells were on virus, their airways were clearer, and they showed fewer and milder symptoms. to look. This result seems to indicate that the lower initial dose as a result of masking resulted in healthier hamsters.

The severity of the original SARS disease in 2003 was also shown to be dependent on the initial viral dose, at least in mice. From these data, together with information about who was infected in a Chinese apartment building with aberrant airflow, a modeling study estimates that people needed 43 plaque-forming units – a measure of disease quantity – to have a 10% chance of measurable disease, and 280 to have a 50% chance of measurable disease.

Of course, H1N1 flu, the Spanish flu and the original SARS do not necessarily behave the same as this coronavirus, and what happens in hamsters and mice does not necessarily happen in humans. So if this dosage theory were true, we would like to see hints of differences as it relates to this coronavirus and humans.

It turns out we do. In cases where we can place similar populations that probably received different initial doses of the virus, we have generally seen different outcomes in their disease.

The first such study is probably from Gangelt, the small German town in which an indoor festival led to a major outbreak of coronavirus. Researchers found that those who went to the festival and caught the large dose in a superspreading event had a longer list of symptoms than those who were not at the festival and caught the disease second hand.

Or take this group of more than 500 Swiss soldiers on one base. They had three firms of roughly similar demographics and an average age of 20. Two of the firms found cases of coronavirus before the military decided to introduce social distance and hygiene guidelines. Despite these new restrictions, the third company eventually saw some members catch the coronavirus, but much less than the original two infected companies: 15% of the third company tested positive in serological tests, compared to 62% of the originally infected companies.

Here’s the thing: Zero of the infected young patients in the third company showed symptoms. Meanwhile, 102 in the companies infected before the Social Distance Guidelines were symptoms. It seemed that the social distancing guidelines not only spread the disease but also prevented the severity of diseases.

Another study looked at three coronavirus clusters in Madrid, all with similar mean ages between 63 and 66 years old. Approximately the same two-thirds of each group had comorbidities. But the first group followed the strict isolation and social distance protocols set up in Spain, the second group often did not follow the protocols, and the third group met before Spain shut everything down and therefore had no distancing protocols. You can probably guess the trend here: The old people who remained socially aloof had less serious illness, even when they became infected.

We can also compare how sick passengers got on different cruise ships. For example, on the Diamond Princess, when we knew almost nothing about the disease, 18% of infected passengers were asymptomatic. On an Argentine cruise ship in which masks were distributed after the first passenger became ill, 81% of infected people were asymptomatic.

More evidence from America? Ninety-five percent of cases of two meat processing plants – in Oregon and in Arkansas – were asymptomatic, much higher than you would expect. Both outbreaks occurred at facilities where masks were required.

There is looser evidence where you can indicate if you want to believe in this theory. One study found that although high-masked countries had lower infection rates than other countries, high-masked countries had even lower death rates. This theory may also help explain the army’s expected death toll in the recent coronavirus outbreak in the United States. Of course, there are overwhelming factors in abundance – not least is our improved knowledge in the treatment of COVID-19 and the fact that more people will die from that spike in the coming days.

A large study published this week found that patients with higher levels of virus in their system often die in hospital, although this does not necessarily mean that they had higher amounts of virus in their initial infection.

None of this evidence is perfect, and it all depends on comparisons that are not one-on-one. You can poke holes in all of these studies, and the sample sizes are often not large. We do not know how the demographics of festival goers in Gangelt compare to non-festival goers, there are many differences between the Japanese cruise ship and the Argentine, and so on.

And we must further note that getting a small dose of the virus is not a get-out-of-jail-free card. Even in groups where you would expect fewer doses of disease, some people get seriously ill – just not that much.

But if you have so many studies pointing to this idea, about various diseases, types and human scenarios, there is reason to take it seriously. Further research would be nice, but we have significant evidence pointing in that direction.

If, as I believe, lower initial doses means a higher chance of preventing serious illness, that would have several important implications for our society.

• It would mean that masks are at least somewhat protective for the wearer. The refrain of “my mask protects you, your mask protects me” is true, fun and community-oriented. It also does not appeal to jerkers who actually only take care of themselves. Masks clearly reduce viral throughput at least somewhat, and thus wearing can reduce the chance of serious illness for the wearer. As a result, more people would wear masks.

• It would have major implications for professionals dealing with COVID-19 patients. If you ran a hospital, a COVID-19 hospital ward with multiple patients in one room could lead to riskier outcomes for physicians and patients than individual rooms.

• If you are a person with a sick family member, it means that there is a protective value when quarantining at home. Sure, you may have driven your sick mate to get the COVID-19 test, but avoiding prolonged and repeated exposure indoors outside of that car ride can still make a difference in the severity of secondary infections. The guest room calls.

• It would further emphasize the emphasis on the exposure of all this. A quick shopping trip at a store with an infected employee is much less dangerous than an eight-hour workday shared with the same employee. Preventing the latter scenario is important.

• It means further emphasizing outdoor activities and indoor ventilation. With those in play, the virus can hang around for less time in midair than in closed environments.

• It reduces our emphasis on ending surface transportation. The amount of virus that lives on a surface is likely to be small and will not be transferred in high percentages to the respiratory area of ​​an unsurprising person who prevents leaking surfaces throughout their life.

In short, knowing this hypothesis gives us a greater understanding of how we should prioritize our day-to-day actions when navigating the pandemic.

If possible, you do not want to encounter the coronavirus. But if you do, try to make it a small dose.

Andy Larsen is a Salt Lake Tribune sports reporter covering the Utah Jazz. During this crisis, he was instructed to dig into the figures around the coronavirus. You can reach Andy at [email protected] or on Twitter at @andyblarsen.