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Saturday, February 7, 2015

Why can't we cure the common cold?

When people find out I'm in med school there are a few stock reactions that happen every time.

The first: Oh! Wow, so, are you smart?
The second: Oh! Wow, do you know why I'm constantly (insert over personal medical problem here)
The third: Oh! Wow, have you cured the common cold yet?

The third is often wrought from people who think they're funny, and due to my great appreciation for dad humor, I happen to agree with. But! I happen to think that it's a pretty interesting topic and actively fight the urge to refute people's claims of "How advanced can medicine be if we can't even treat the sniffles?" on facebook. I don't want to be THAT girl.

As most of you who have had a biology or human science class will know the common cold is a virus and we can't treat viruses with antibiotics, voila, finished! Just kidding! There's a lot more to it than that-- and that my friends is why we pay doctors to help us and not 14 year olds in freshman biology.

You might be wondering how we can prevent a virus like Polio or HPV through vaccines but other virus borne illnesses -- HIV, Ebola, or the sniffles go un-vaccinated. Well, that's because all viruses do not share the same morphology or virulence pattern. Unlike us homo-sapiens, viruses have a much wider range of diversity than we see amongst ourselves because they are not all wrought of the same species. They're also not living so I don't think species is the correct word but it makes the point. Viruses are sneaky because they're these little guys who are comprised of a shell and some form of genetic material and they get into their hosts' bodies, replicate with their hosts replication machinery, and either take over that cell or kill it. Rude! There are some other options but for the sake of everyone who hates delving into the depths of immunobiology (myself included), I'll only discuss the big players.

The big idea or "thesis" if I were in AP English again is: Viruses are really tricky for two reasons: the first- they often integrate themselves into our DNA and the second- they mutate and change enough of their genetic material to be invisible to our medicine.

Aside from dodging our drugs viruses are also really hard to make drugs for in the first place. Unlike bacteria who travel with all of the tools required for life viruses are like that weird friend who crashes on your couch for a month. They bring what they have to and will use whatever you've got to fill in the gaps. Because of this we have a ton of options of where to hit bacteria; their replication machinery, their genome, their cellular structures, all over the place. On top of that, bacterial structures are fairly unique to ours and their membranes are chemically distinct. On the other hand, a virus can survive with its genetic material and its little envelope to hold it. Sure, we can target those things but as mentioned before as soon as viruses get into our system they get into our cells and integrate with our stuff, effectively playing a really annoying game of hide and seek. Even if they aren't integrated into our cells a virus is much less likely to be eliminated by simply disrupting its membrane like bacteria- they're much more resilient.Vaccines work in the same way our immune system does: by building antibodies against the viral components so that our immune system can recognize them and kill them. Vaccines are nice because it takes away the lag phase where our bodies have to recognize the virus as foreign, generate the antibodies, and attack them. The virus has already been recognized and the antibodies are ready to go. Thus no lag phase, thus we don't get sick.

So, why can't we replicate what we've done with vaccines for the common cold? It all comes down to the fact that there are a lot of viruses that cause the common cold and they replicate and mutate incredibly fast.We can make vaccines for any given virus but by the time it is available the virus will have mutated to a form that won't be recognized by our vaccination produced antibodies. I imagine viruses as con-artists; the second you get a handle on what they are they've already changed and now you've got to start over. That's why the flu vaccine isn't 100% effective, it isn't the current strain. They make the vaccinations with the previous year's strain and hope the virus doesn't mutate completely beyond recognition.

Whether or not there is a possible cure for the common cold comes down to logistics- it just is not currently feasible to create a new drug that targets a virus that will be different in a week. If someone REALLY wanted to, I bet they could but the chance that anyone will then have that strain is pretty low. We can treat the symptoms but at the end of the day we still have to let our immune systems do their jobs and that takes a little bit of time.

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