Hi, my name is Don Sheppard I'm the director of the McGill Interdisciplinary
Initiative in Infection and Immunity and I'm recording
this from my office here at the McGill University Health Centre where I've just
completed a week on the COVID wards and I'm pleased to report that indeed as you
read in the news our case numbers are dropping and the amount of disease we're
seeing is going down so that has put us in kind of a limbo state and that's what
I want to talk about today how do we coexist with COVID in this new period
where the rates of disease in the community are going down but we don't
have a vaccine so we're kind of coexisting with the virus and trying to
figure out how to manage risk and so as you go back to work as the restrictions
are lifted it's important to think about how are you personally going to manage
risk and when you manage risk I think there's a few things we can think about
so I'm going to divide it into three big topics the first is your encounter risk
so obviously the less virus that's circulating in the community the less
risk you have but there's some caveats there even though there may be a low
number of cases today we know that the cases are actually only telling us what
happened in terms of transmission a few days ago to a week ago and we saw this
during March break when it wasn't which countries you went to that had corona
virus that were the problem it's which countries you went to that the week
later had coronavirus because people were transmitting before they were
symptomatic so you do have to view this with caution and we've seen in Germany
and South Korea that there are these micro outbreaks that actually will
continue to happen and we need to be vigilant about those so you need to pay
attention to that you need to listen to Public Health tracing and make sure that
you're aware of where you are so that if there are micro outbreaks we can deal
with them and most importantly if you are symptomatic you need to stay out of
your workplace you need to stay home and you need to get tested because if you
don't get tested we can't identify this micro outbreak we can't find your
contacts and we can't extinguish that particular little micro outbreak so
that's kind of the exposure your chance of actually meeting up with someone who
has virus then the next big thing is of course transmission and it seems silly
to talk about transmission we all know how this virus is transmitted
predominantly through the air and obviously if you're standing next to
someone who has coronavirus make off in your face you have a high risk of
getting Corona but that's not our reality right now a
reality right now is figure out how we work with people who are appear and feel
healthy but maybe asymptomatic transmitters either because they're
never going to develop symptoms or they're in the pre-symptomatic phase so
let's say you're in your work environment or your day-to-day life and
you do encounter unknowingly someone with coronavirus how do we know whether
they're going to transmit to you and there's actually a very simple kind of
formula that you can think about and that is the amount of time and the
exposure why do I say that because it's not one single virus particle that's
going to infect you you need many virus particles your innate immune system the
defenses that your body has against all viruses whether you're immune to them or
not can eliminate a lot of the viruses that you're exposed to and we think the
infectious dose of corona virus may be as high as several million intact viral
particles that you have to inhale before you're going to get sick so if you think
about this what does that mean that means that when you're walking past
somebody in the corridor if they don't cough directly on you you're not likely
to get exposed to enough particles to get sick but flip that around the other
way if you are in an enclosed space and you
are with somebody for a long period of time even if they're not generating a
lot of virus particles when they talk when they laugh when they breathe if
you're in that enclosed space as they are generating those particles they can
build up in the air and you can breathe in a low dose over time to become
infected so that's why outdoors is safer than indoors because those particles can
be diluted that's why mass and other barrier
precautions are helpful because of course they block the transmission of
the virus so what can you do then if you think about these principles to protect
yourself well obviously the first thing you can do is limit your exposure time
the less time you're around somebody the less chance of risk and similarly short
exposures we know are very low risk so you can relax a little bit about
crossing someone in an elevator crossing somebody in a hallway because the
chances that they can transmit the virus to you in that very short period are
actually fairly low unless they're really sick and there's a
serious direct exposure you can also look at your environment so we obviously
can't move all of our work outdoors but whatever work we can do we should think
about working and moving outdoors we can't actually move air indoors in
buildings but we can open windows what we shouldn't do though is use fans
because fans can disperse the virus further than they would go normally
similarly you want to distance yourself from people of course because when they
cough and breathe the particles can only go a certain during a distance and the
further you are away the less particles are gonna reach you and when I talk
about outdoor indoor don't just think about the actual work you're doing but
think about your lunch brings your coffee breaks and the time that you are
waiting for things to happen at work you can go outside if you're gonna have a
coffee break with someone go outside two meters away and at that point your risk
is very low and if you have to be in the same space with somebody that's where
barrier precautions come in whether it's masks which we think if they're on a
sick person can reduce transmission up to 85% or if they're on you where most
of us still think that they can reduce the chance that you inhale biros
particles somewhat and lastly of course major barrier precautions plexiglass or
whatever when you have a fixed interval that you cannot avoid in a prolonged
exposure there's a virus of course does not go through plastic so these are just
a few thoughts and tips but remember of course as we learn more about the virus
the situation continues to change and these guidances from public health and
other agencies may of course change over time so you need to be aware of what's
going on listening to new guidances and be ready to change so I hope these are
useful and I want you to go have a great day and of course above all else stay
safe