The early days of the coronavirus pandemic were a confusing time.
There was a lot of conflicting information flying around
and it was hard to know what to believe about how the virus behaved and the best practices to stay safe.
Since then, things have stabilized somewhat and the official advice from public health organizations hasn’t changed much:
wash your hands, avoid crowded indoor spaces, wear a mask, and practice social distancing.
A lot of these precautions are based on the belief that the virus isn’t airborne,
but some researchers are now challenging this notion.
So, what is at the heart of this debate, and how does it affect you?
Airborne can be something of a confusing label.
Right now, it’s widely accepted that the virus is carried by the droplets that we expel when we talk or cough.
These droplets do travel through the air, but aren’t considered “airborne” because they typically fall out of the air immediately
and land within about two meters.
Hence the recommended social distancing guidelines.
But smaller than droplets are aerosols — tiny particles that, as a rule of thumb, are under 5 microns in size.
For reference, that’s smaller than a single red blood cell, which are typically about 6 to 8 microns in diameter.
These tiny specks can be suspended in air for much longer by air currents, so aerosols are airborne.
Since the 1930’s, the consensus was that aerosols were not a major transmitter of respiratory viruses like influenza.
When the novel coronavirus emerged it was categorized as a respiratory virus too,
but oddly its symptoms are so varied it behaves in some ways like a vascular disease,
and scientists still aren’t clear exactly how this new virus operates.
If the virus was really just carried by droplets, there are some instances of infection that some scientists say shouldn’t have been possible.
Proponents of the aerosol transmission possibility point to a choir practice in Washington state
that led to 33 members of a 61 person group to contract the virus.
They claim it supports their notion that aerosols, poor ventilation, and long exposure time were to blame.
Other investigators couldn’t rule out droplets or infected surfaces as culprits, though.
You may be wondering why the World Health Organization won’t say definitively if the virus is airborne or not.
They maintain there’s just not enough proof yet.
One problem is that devices that sample for aerosols can damage a virus’s protective lipid envelope,
resulting in an undercount of how many viral particles are actually present in the sample.
We don’t know how long the virus can stay suspended in air and remain infectious,
though one study reports that can be as long as 16 hours.
We also don’t know how much of a viral load is needed to cause infection.
If it turns out a relatively small number of viruses are dangerous, then aerosols would represent more of a threat.
Still, there’s enough concern that almost 240 clinicians, infectious-disease physicians, epidemiologists, engineers, and aerosol scientists
published an open letter to the World Health Organization pushing them to reconsider their position
and their advice on how to combat transmission.
The authors argue the WHO’s standard of proof is too high,
even though they claim more evidence exists of airborne transmission than passing through droplets or surfaces.
The WHO has since changed their stance somewhat and now says it's possible that the coronavirus is carried through aerosols,
but they’re not recommending precautions like improving ventilation or using upper-room UV light to kill it.
Part of the reason they haven’t pushed for additional precautions is because they have to consider the cost of following their guidelines.
If countries with scarce resources implement measures that are ultimately meaningless, it can keep them from focusing their efforts on effective precautions.
Then again, if the virus is really transmitted by aerosols, then insufficient measures can cost lives too.
It’s not an enviable position to be in.
But what does this all mean for you, specifically? What should you change?
Well, if you’ve been wearing a mask and avoiding spending long periods of time inside crowded and poorly ventilated buildings, you’re already on the right track.
These are already the guidelines the WHO recommends.
Even cloth masks can help break the chains of transmission.
Less so if the virus is carried by aerosols, but a well fitted mask that covers the nose and mouth can still help.
Aerosols can build up indoors and the more people there are, the more likely that someone is shedding the virus.
So again, don’t linger inside around people if you can avoid it.
Researchers are still debating whether or not the virus is airborne but it shouldn’t really change the game plan for most of us.
Continue to do your part and look out for yourself and others and we can get through this.
As events unfold, we have kept up with the scientific understanding of the novel coronavirus.
If you want to know more about this topic check out our coronavirus playlist here.
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Thanks for watching, and stay safe.