General Discussion
Related: Editorials & Other Articles, Issue Forums, Alliance Forums, Region ForumsYale Immunology prof answers questions, such as "Will summer save us?" Very informative...
[Here are some excerpts. There is a lot more, all of it interesting. The last paragraph that I posted suggests that social distancing over time--I would imagine a long time--makes the virus adapt to become less virulent.]
http://nautil.us/issue/84/outbreak/summer-wont-save-us-from-covid_19
What role did winter play in the spread of the pandemic?
Winter definitely plays a role because we know, by studying many other respiratory pathogens, that the winter months provide an ideal situation for viruses to transmit in the air. If you look at the influenza virus, the peak is in winter. Part of the reason for this is because we have low humidity indoors during winter, and that is an ideal condition for the virus to survive in the air. Another part is the fact that our defense against respiratory viruses declines in low-humidity settings. These things usually contribute to infection and transmission of influenza and other respiratory viruses.
Why does low humidity help the virus spread?
What happens when you cough or sneeze is that you expel the virus particle inside these droplets. When the droplet hits the air, and its very dry, it loses the water content and it becomes desiccated. Little dried particles float in the air, and they tend to persist in the air for hours. Whereas if the humidity is high, those droplets acquire water vapor from the air, and they become larger and they drop on the floor instead of infecting someone else. The low humidity basically allows these aerosolized particles to remain in the air for much longer because they dont retain the water very well.
Did another winter factor come into play?
Likely sunlight, because its important to metabolize vitamin D. In the winter, people tend to stay indoors more often and theyre not getting enough sunlight. Vitamin D is well known to boost the immune system. Thats another winter factor that might affect the persons ability to defend against the respiratory infection.
Were not even at the peak of it. We are just bracing.
Will summer save us?
No, this doesnt mean summertime will basically cure the virus. The aerosol transmission will likely reduce in the summer, but the direct transmissionas well as fomite transmission through things like skin cells and clothesis still going to happen.
What sets this virus apart from common cold coronaviruses?
Definitely this virus is more virulent, more lethal. You dont really die of the common cold, but this virus kills. The other difference is it seems we dont have any prior immune response to this version of the coronavirus, so nobody has resistance. Whereas with the common cold, most of us have been exposed multiple timeswe have antibodies and T-cell response, so the disease is much milder. This virus also has a very long incubation period. You might be infectious but you dont know, because you dont have any symptoms. That makes this virus very contagious, with the ability to spread well among humans. The key gap in the field is to try to understand what type of immune response is protective. We still dont know exactly what were even aiming for with a vaccine. We dont know which type of antibody responses confer protection versus which type will trigger worse disease. Similar for T-cell response, and so on. These are insights needed for therapy and vaccine strategies.
How does a novel coronavirus differ from viruses that have been with us for a long time?
If you look at pandemic viruses that emerge as human-to-human transmission for the first time, they tend to be quite virulent, at least the ones that we understand, we know of. When a pandemic flu, or this COVID-19, first emerge in humans and start transmitting, they tend to have quite high virulence. What happens is that the virus will eventually be selected for its ability to replicate and transmit. Those features might be in conflict with virulence because if a virus makes you so sick that youre not going out of the house and infecting other people, then the success of the virus dies right there. For viruses that have been circulating for many years, like the rhinovirus, you usually dont get so sick to a point where you stay home and dont interact with anyone. That sort of makes these viruses much more successful than if a virus were to kill you immediately. Theres a balance that the virus has to strike to become successful. Over the years, usually the virus thats circulating in humans tends to have less virulence so that people go out, infect others. Im not sure whether thats going to happen to this particular virus.
Cracklin Charlie
(12,904 posts)Thanks for posting it!
Laelth
(32,017 posts)-Laelth
duforsure
(11,885 posts)Then sued for political malpractice too. Making false claims daily lying about something like this is evil . Intentionally misleading the American people in a health crisis isn't making us great , and his followers are realizing that now. Forcing people to work while a pandemic is attacking will also get their attention how corrupt and evil he is too.
trumps stiffing America now
NNadir
(33,583 posts)Hortensis
(58,785 posts)the average annual temperature exceeds 74.something Fahrenheit. Where we are now in FL is only 70-72. But in any case, we're talking about hot climates. This virus likes the temperate climates most humans do best in also.
blitzen
(4,572 posts)Hortensis
(58,785 posts)at certain latitudes the rates of infection are consistently lower.
Chainfire
(17,757 posts)That is Summer time weather for a great part of the country, and we have not had any miraculous halting of the virus.
Igel
(35,387 posts)Think of it as a brake.
When you brake you don't suddenly stop. Most of the time you don't even stop. You slow down a bit. (Unless you're in Los Angeles, Manhatten, or I-45 in Houston, then since you never get moving fast "slow down a bit" = "stop."
So the interviewer asked if summer will stop the virus. Answer: "No." But the epidemiologist continued to say that transmission will be reduced. Then he points out ways it might still be transmitted--direct contact and fomites. (Although that last hasn't been demonstrated yet, as far as a I know). And, of course, it will still be transmitted by aerosols and droplets.
It's the same conceptual problem that many had with saying that younger people were "at lower risk." Many assumed it was all or nothing, and if they weren't "at (special) risk" it meant they were "at no risk."
Steelrolled
(2,022 posts)It is so annoying when people assume things are so black and white. So much of our medical advances (e.g. treatment of cancer) have occurred slowly, but over time it adds up. I've seen it first hand.
thesquanderer
(12,000 posts)...the article posted at https://www.democraticunderground.com/100213257153 which indicates little confidence that this particular virus will be highly impacted by increases in temp/humidity.
blitzen
(4,572 posts)the subscribers-only wall. Humidity definitely lessens transmission--it's clearly explained by the Yale prof: water vapor weighs down the virus particles and brings them to the ground.
thesquanderer
(12,000 posts)From the DU post:
Additional from the linked NYTimes article:
...
The report sent to the White House also struck a cautionary note: Given that countries currently in summer climates, such as Australia and Iran, are experiencing rapid virus spread, a decrease in cases with increases in humidity and temperature elsewhere should not be assumed, it said.
Pandemics do not behave the same way seasonal outbreaks do. For the National Academies report, researchers looked at the history of flu pandemics as an example. There have been 10 influenza pandemics in the past 250-plus years two started in the Northern Hemisphere winter, three in the spring, two in the summer and three in the fall, the report said. All had a peak second wave approximately six months after emergence of the virus in the human population, regardless of when the initial introduction occurred.
dameatball
(7,405 posts)mahatmakanejeeves
(57,727 posts)What? Evolution? Not with Pence in charge.
blitzen
(4,572 posts)Steelrolled
(2,022 posts)showed this effect for their covid-19 outbreak. In other words, transmission was lower with high heat/humidity, after trying to remove other factors such as economic status. I'll take anything we can get.
IronLionZion
(45,628 posts)that's a big seasonal factor for other viruses. Children spread the common cold very quickly.