If you’re at home social distancing, or sheltering in place like me,
you’re probably as weary of all the coronavirus news as you are tired of staying indoors.
And that’s fair. Really.
I understand why maybe you’d rather watch a video on ghost particles from Antarctica,
or making oxygen on Mars—
or, for pure escapism, binge watch Tiger King.
But I want to explore an important and pressing facet of the COVID-19 coverage: antivirals.
Something that you may have heard mentioned in conjunction with developing vaccines to fight COVID-19.
“We’re not a vaccine company. We’re a therapeutic company focused on antivirals.”
“We have to make sure that we've tested all of the antivirals that you have in your collection."
"There are a number of antiviral drugs that are being tested.“
So, what exactly are antivirals?
Simply put: antiviral drugs are medications used to treat viral infections—
as opposed to bacterial infections, which are treated using antibiotics.
Moving beyond this tautology, antivirals inhibit a virus’s ability to replicate.
This also means they are most effective when administered shortly after infection,
before the virus has infected too many of the host’s cells.
Unlike vaccines, which serve a pre-emptive line of defense
by training the body’s immune system to fight pathogens,
antivirals are by and large administered to people who are already infected with a virus.
Another key difference: antivirals are effective only during the time they are being administered.
So essentially, antivirals are an effective near-term solution to prevent viral infections from getting worse.
But they’re no magic bullet.
Nearly six decades since the first antiviral drug was approved for use,
antivirals have been approved to treat a number of human diseases, including:
herpes, chicken pox, HIV/AIDS and Hepatitis B & C—to name a few.
Okay. Now that we’ve got the basics down—what do antivirals have to do with COVID-19?
In January, China shared the genome sequence of SARS-CoV-2,
the official name of the virus that causes “coronavirus disease 2019,”
more commonly known as COVID-19.
That’s right, as of this video’s publish date, researchers have had only three months
to study the new virus’s genetic sequence.
Which means, we are still just learning about this specific coronavirus.
Fortunately, researchers can use what we know about other coronaviruses that cause human infections—
like the MERS virus and the SARS virus—to make some educated guesses about SARS-CoV-2.
You may recall that coronaviruses have a crown, or corona, of spike proteins that they use
to connect with cell receptors on the outside of host cells.
Specifically, SARS-CoV-2 uses ACE-2 as a receptor to bind to the host cell.
Researchers believe that SARS-CoV-2 follows the same process of replication as other coronaviruses.
After binding, the virus fuses with the cell and releases a copy of its RNA genome.
Then through assembly, transcription and translation, uses the host cell to make copies of itself.
These complete, infectious particles are called virions.
Finally, these virions are released to infect adjacent cells.
Now, different antiviral drugs are designed to target and inhibit different steps in this process of viral replication.
Some target receptors early in the process to stop fusion to the host cell.
Others stop replication of the genome.
And others disrupt the assembly of new copies, or stop the release of new virions.
As of this video’s publish date,
the total number of confirmed cases of COVID-19 has exceeded 1.5 million worldwide,
and that total is projected to continue growing.
And with experts saying that it will take more than a year for a vaccine to be ready for the public,
researchers around the world are racing for a near-term solution in the form of an effective antiviral treatment.
Instead of developing new drugs to treat COVID-19—
which would likely take about a decade to reach the public—many are looking to repurpose antivirals
that have already gone through rigorous trial and approval processes to treat other diseases.
Two examples: the antimalarial chloroquine,
and its derivative hydroxychloroquine, which is also used to treat rheumatoid arthritis.
Both have been mentioned repeatedly in the U.S. Coronavirus Task Force briefings.
Now, just to be clear, there’s currently no definitive evidence that either of these antivirals
are effective treatments for COVID-19.
Researchers still need to fully evaluate the efficacy of these drugs against COVID-19.
But some researchers think these drugs could potentially stop SARS-CoV-2
by disrupting binding and interfering with the process of depositing its genome into the host cell—
stopping the virus early in the process of replication.
Chloroquine and hydroxychloroquine also calm immune response,
potentially inhibiting a dangerous overreaction from the immune system.
Part of what kills people with this virus is the immune response that follows the infection.
It ends up causing severe inflammation in the lungs or throughout the whole body, causing multi-organ failure.
Dr. Otto Yang and his team are looking at another antiviral that you may have also recently heard of.
At UCLA, we have an ongoing study of remdesivir, which is the antiviral drug that's gotten a lot of press.
Remdesivir is an experimental antiviral initially developed to treat Ebola,
that inhibits viral replication by disrupting RNA transcription.
But there’s a chance that it might also suppress the immune reaction and inflammatory response
that has been a known cause of death for COVID-19.
We are setting up trials of things to dampen down that immune response,
and see if it can help prevent that damage and reduce mortality.
Although it is a double-edged sword because the immune system is there to fight the virus,
so you don't want to dampen it and then lose your ability to fight the virus.
There’s also Favilavir, a drug that’s used in Japan and China to treat influenza
and is currently being touted as “the first approved coronavirus drug.”
Now, it’s important to keep in mind that while China has approved it as a treatment for COVID-19,
it’s hard to even verify what clinical trials were done in China to vet the drug.
The reality is there’s currently no definitive evidence that any of these antivirals
are effective treatments for COVID-19.
Which is why, as of this video’s publishing,
there are no FDA-approved drugs specifically for the treatment of patients with COVID-19.
The FDA has approved emergency use of chloroquine and hydroxychloroquine for the treatment of COVID-19.
But in the same statement, released on March 28th,
the FDA reiterates that “Chloroquine phosphate and hydroxychloroquine sulfate
are not FDA-approved for treatment of COVID-19.
So, it’s a little unclear when and how these drugs can be administered.
Which may make it difficult for patients to understand what therapies are available to them.
The bottom line is, while researchers are excited about repurposing antivirals to fight COVID-19,
they need more time to ensure that the drugs work against the novel coronavirus,
and to confirm what dosing is most effective and safe for public consumption.
So, we’re all probably stuck social distancing for a little while longer.
That said, this pandemic has motivated and united the medical community
to find an effective near-term treatment.
And many governments and companies around the world are fast-tracking testing,
trials, and approvals to find one.
And you can be sure that we’ll be all over it when a safe and effective antiviral treatment—or vaccine—is found.
If you want to learn more about COVID-19, check out our video here.
And if there’s another aspect of COVID-19 that you want to see us cover, let us know in the comments below.
And make sure to subscribe to Seeker for all your viral news.
Thanks for watching, and I’ll see you next time.