New Coronavirus information

 New sooner have I posted about the Coronavirus then a couple of new things come up.

Yesterday I came across a really great paper, Beyond Six Feet: A Guideline to Limit Indoor Airborne Transmission of COVID-19.  It's related to a tool for figuring out risks of indoor aerosol transmission but the information in that paper was what was really interesting to me.  I'd thought that aerosols were only generated by our lungs' alveoli but apparently they can be generated by vocal cords too when you use them to speak, sing, etc.  I suppose the bit I had read earlier was making the simplifying assumption that people are silently sitting still or something.  Anyways, I'd been really interested in how much of what size of aerosol or droplet was generated by what sort of vocalization and what should this paper have but the graph I'd always wanted.

    I'd previously been told that 2.5 micron aerosols are most common which looks to be approximately true for nose breathing but really leaves out the breadth of sizes that are generated.  That's important because there's a big difference between how well masks block 3 micron particles versus how they block .3 micron particles - the later are much harder to stop.  Singing in particular looks pretty bad here even if people are wearing masks.

    The other thing is that there's a new variety of the virus that's been spreading in England and has me really concerned. It involves several mutations including some to the spike and seems to be spreading from person to person faster than normal SARS-CoV-2, making it a new strain rather than just a variety.  There are three pieces of evidence right now that this is a different strain.  First, the prevalence of this strain has been going up in England at a constant rate week by week making it seem like it has a reproductive advantage.

    Second, the number of cases in areas where this strain is active are seeing much larger growth in the number of cases than other areas.

Finally, and I don't have a fancy graph for this one, it looks like the new virus strain might have a "decrease of ct value of around 2" and genomic analysis says "0.5 increase in median log10 inferred viral load" from the same meeting minutes.  Which would suggest people infected with the new strain might have 3 or 4 times as many virus particles in their phlegm than the previous strain.  In theory, that would mean that you would have to spend one third as much time with an infected individual to get an infectious dose yourself.  

If this new strain is really as infectious as the evidence is suggesting right now, and I think with three points of evidence it probably is, then we shouldn't expect existing measures that are barely keeping the virus in check to be sufficient.  Most of Europe has already banned flights from the UK which to me is the obviously right move in response to this.  Travel restrictions have a bad reputation but that seems to have been the result of a game of telephone simplifying the situation and for human to human transmissible viruses without a known cure that isn't the situation.

Thankfully there's every reason to think our existing vaccines will be effective against the new strain.  The Covid spike protein has about 20 sites which our immune system targets with antibodies.  For one of these twenty it might be that that particular antibody will be less effective, or possibly totally ineffective or just as effective - we don't know right now.  But for the other antibodies targeting the other site our immune response will be just as good.  

So lets make sure to vaccinate as many people as possible.