Thread by @Craig_A_Spencer

🖍️ & 🥃 Episode 4: PATHOPHYSIOLOGY

Today we tackle 'pathophysiology', or the abnormal changes that occur in the body due to #COVID19.

If you're looking for information on #COVID19 testing or transmission, check 👇or my Twitter page.

Otherwise, let's go!
bit.ly/35uROzj

So the first question is: What is this coronavirus?

The scientific name of the virus is SARS-CoV-2.

It belongs to the coronavirus family which includes viruses that cause MERS, SARS, and the common cold. This particular coronavirus spreads primarily via droplets and surfaces.

After the virus gets into our system via our nose, eyes, or mouth, it attaches to a receptor in the nasal passages & throat.

Here the virus uses 'spike proteins' to inject its genetic material into a host cell.

And then it takes over! AMAZING explainer👇
nyti.ms/3c03vAi

In this way, the virus replicates and slowly makes it way down towards the lungs.

When in the lungs, it can wreak havoc by causing massive inflammation.

This creates some of the biggest problems we see in #COVID19 patients - difficulty breathing & ARDS (more on this later).

This is because the virus uses our own proteins to create countless copies of virus particles, which ultimately get released to infect more cells.

These infected cells then alert our immune system by presenting parts of the virus to white blood cells, our natural defense force!

A lot of the problems we see from COVID19 are due to this inflammation, not necessarily the virus itself.

The immune system can get really eager when dealing with infections, and can go 'overboard' - that is why sometimes we feel sore, body aches, and just overall sick.

The immune system releases molecules called cytokines to mediate this inflammation.

Moderate levels of cytokines target the infection while not hurting our own cells.

However, too many cytokines (a cytokine storm) can cause a lot of collateral damage to our organs.

When the immune system tries to clear out the infection from lung cells, the inflammation can cause fluid to build up in the lungs, making it harder for them to exchange oxygen.

This is what causes the low oxygen and breathing problems with COVID19. It also causes ARDS...

Acute respiratory distress syndrome (ARDS) is one of the serious complications seen in many patients with #COVID19.

It occurs when fluid and inflammatory products fill up the lung sacs. They no longer function well enough, and often these patients need to be put on a ventilator.

Now, there's a lot of uncertainty over why people seem to respond so differently to the virus.

What we DO know is that people who are older and have heart, kidney, and lung disease, diabetes, hypertension, cancer, and obesity are at higher risk of severe illness and death.

People with immune system complications (i.e. autoimmune conditions or immunosuppressed) are considered high-risk & should be extra-careful with protective measures.

This is because their immune systems don't function as expected, and can have unexpected responses to the virus.

ROLE OF GENETICS:

It's likely that genetics can affect individual responses to COVID-19, but we're not sure right now.

Fortunately a COVID-19 Host Genetics Initiative is currently performing genetic studies & released a preliminary report as proof of principle. (covid19hg)

So what about kids? Indeed, kids aren't getting as sick with COVID.

We're not sure why, but there's 3 possibilities:

1) The virus receptor levels (ACE2) are lower in kids

2) Kids' immune systems are not as strong

3) The virus competes against other viruses in kids' lungs

Interestingly, males seem to be more severely affected than females.

And we don't know why.

The amount of protein used by the virus to infect the lungs is higher in males than in females.

So maybe males may have a harder time getting rid of the virus from the body (?)

BLOOD CLOTS:

We are seeing that COVID patients develop blood clots. What are these clots exactly? All healthy people constantly form and dissolve tiny clots throughout the body. When clots persist and travel to various organs, these organs don't get enough blood to stay healthy.

In general, the virus seems to cause damage to blood vessels, which causes more clots to form.

Being stuck in an ICU can also increase clotting risk, as stagnant blood is more likely to form clots.

And it seems that standard anti-clot therapy doesn't really help as much.

Some clots can travel to the brain. These can stop blood flow to parts of the brain & cause severe strokes.

Typically, strokes occur in ages >60.

But in COVID patients, these are also occurring in people ages 30-50s.

We're still trying to understand exactly why clots form.

And lastly, MUTATION!

The coronavirus IS mutating. All viruses do. Mutations occur naturally during replication, and some mutations may help the virus sneak past our immune system.

However, we're still unsure whether mutations are affecting treatment options or illness severity

Again, this @nytimes article with illustrations is an awesome piece on how coronavirus mutates and spreads:

nytimes.com/interactive/20…

And there it is!

For our next episode, we’ll tackle treatments!

This thread (and future ones) + all supporting articles & research can be found at: bit.ly/3bRycHQ

As always, a huge thanks to @TylerWen & @saurabhsudesh for helping put this together! Give 'em a follow!

Thanks to everyone who asked questions on pathophysiology: @pedlup13 @sarahbee_34 @selznicksakki @donaldverger @litwife @cindyvebu
@mguru2020 @giantbunnylove @nsalas_t @rattyhattreout
@berry89508197 @kurtdonovan6 @romanscollins @selznicksakki @nimbusnugget @loridow71 @ceartas4

@cr3ativ2 @kaythomaswrites @emmah7 @litwife @cindyvebu @litwife @SamDR

And as a reminder, the goal is to share something like this every night for a week at ~9pm to address big questions around testing, treatments, vaccines, pathophysiology and more!

Powered by 🖍️ & 🥃.

Be safe!