I'm very pleased to say that with me
today is dr. Elisabetta Grappelli she's
a lecturer in global health at st.
George's University of London she's an
expert on the spread of viruses and
social distancing measures and I'm also
joined from the University of Cambridge
by the virologist and presenter of the
naked scientist podcast dr. Chris Smith
welcome to you both maybe I could start
with you dr. Chris Smith on masks
because there's a lot of talk at the
moment about masks and here is one from
Terence in Newport in Wales can I make a
mask at home and what would be the best
material and once used would the fire s
be destroyed by cleaning or heating it
hello Terence to be honest with you the
current evidence we have and the
guidance the public health England are
sticking to is that these masks are not
going to be helpful in in the hospital
setting used appropriately the right
sort of mask in the right sort of
setting with the right sorts of
additional protection including
protection for your eyes they can save
lives they can be very helpful but for
general public walking around in the
supermarket for example getting your
shopping they're probably not going to
do you any good
the only possible exception to this is
if you wear a mask and you're highly
symptomatic and you're coughing and
spluttering they might cut down the
creation of what we call an aerosol the
release of virus particles into the air
around you that might then go on to
infect other people they might reduce
that a bit but the kinds of masks
available to the general public and the
materials they're made of don't actually
cut down as far as we can tell the
transmission any better than just
adopting the other social distancing and
hygiene measures that the government are
urging you to use because there's a
debate now isn't there in the United
States the mayors in Los Angeles and in
New York as saying we're anything to cut
down as you say the aerosol effect yeah
there's not really any compelling
evidence behind this what we do know
about these masks is that usually people
don't fit them properly and they don't
form an airtight seal around your mouth
and in fact I was watching a television
program the other night some people in
Italy and from the camera angle I could
see the individuals mouth round the side
of the mask now if I could see it from a
television camera that means the virus
which is one ten thousandth of a
millimeter across that's a gaping great
hole for the virus to sneak in through
no problem there so people end up with
air leaking all around them
also if you've got something on your
face it tends to encourage you to touch
your face more often not less often and
that means if you've touched a surface
that has the virus on it there's a
chance that you could then transfer the
virus to the mask and with prolonged
wearing they tend to get damp and that
dampness actually encourages virus
particles to go through the mask so you
could actually increase the chances of
picking up the virus so it's better to
just follow the guidance we think at the
moment that the government's giving out
which is stay away from people because
people are the only source you've got to
catch this virus man infected person
that's the only source wash your hands
in case you've touched the surface that
might have viruses on it and stay at
home good advice
sadly the death rate is rising
Elisabetta here's a question some have
asked from Eileen O'Toole when a person
dies of the virus does the virus die too
the short answer is yes it will but
unfortunately not exactly at the same
time as the person so that the virus we
know can the survive on surfaces and so
it will be able to survive as you know
into tiny in the hours they were after a
person who has unfortunately died and so
it's crucial that a you know appropriate
PPE is actually used to prepare the body
for for for funeral info burials and
also it's absolutely crucial and there
are recommendations obviously about
maintaining social distancing during the
funeral itself and is this why we're
having such tight regulations around
funerals absolutely and I am I am from
Italy where funerals are a big event
with lots of people and those have been
particularly you know spelt out in the
legislations about it only two or three
close family members that could be
allowed to participate at a funeral okay
here's one Chris from John killin in
Bedford Bedfordshire who is being tested
everyone with symptoms or are they
testing to see who has it okay the
government have drawn up a specific case
definition if you've got the symptoms
and those include a fever which is more
than 37 and about half those and
some degrees and you have a new cough
that's how we're defining someone who's
potentially infected at the moment if
you have those symptoms and you've come
into hospital and we need to bring you
into hospital for treatment then we
would do a test on you at that stage
because we need to know what you've got
wrong with you and what you've got wrong
with you determines how you get treated
and we're in the hospital you'll put
because one of the most important
priorities is to do infection control
and we cohort patients what that means
is we put people together who've either
not got the virus or have got the virus
because in that way we're not spreading
the infection to uninfected at-risk
people so that's one group the other
group that can get tested under Matt
Hancock's number one pillar these are
health care workers because we know that
a significant number of people are
currently at home who could be at the
front line and this is because a member
of their family or they themselves have
some of these symptoms but because these
symptoms are so common and they're
shared with many other respiratory
infections it could well be that they
don't have corona virus they have
something else much more trivial and
they don't need to worry so testing them
will enable us to return more members of
staff to the frontline as the number of
tests increases towards the goal of
public health England think we need
about 25,000 tests to be done per day in
order to meet the needs of doing our
health care how we're going to move
patients around test out healthcare
workers then once we get to that stage
other pillars of the testing algorithm
will kick in and that means we'll be
able to test more people potentially
also test people for long-term immunity
but at the moment it's all about who's
got the virus right now so we can sort
out who's infectious and who's not
Elisabetta the health sector II said
yesterday they'd supplied forty five
million pieces of PPE masks gloves gowns
to the NHS in one day so sandy Goldsmith
from Instron can ask what happens to all
that used PPE is it being recycled is it
burned is it laundered what happens to
it unfortunately if the PPE has been
used in in a healthcare environment
especially in the context or the
infectious diseases that large amount of
PPE is gonna have to be disposed the
safe
and appropriately and the usual channels
are to dispose of this of this waste
there is absolutely not recycling it but
it's actually incineration I know it's a
large amount but it's it's the only way
that actually make sure that we are safe
because reusing increases their chances
of you know I'm transmitting infection
Chris I don't know if you go for a Boris
run everyday I know I do it's the only
way I can get by but Fiona Marlow asks
from Weymouth in Dorset when I walk for
my daily exercise there are lots of
runners like Christian and cyclists who
pass me breathing heavily am I at risk
of contracting the virus well if you get
close to another person and you share
air with that person for an appreciable
at the time and they've got something
that they could infect you with yes
there's a slim chance you could catch
something but you've got to remember out
in the fresh air a there's a huge
dilution effect anyway and B if that
person's feeling like they've got
coronavirus the chances are they're
probably not going to be pounding the
pavement they're going to be doing what
Boris is doing and they're going to
actually be in bed because that's where
we're told use at the moment we're told
chances are they're not going to be that
infectious when they're out and yes I
know what you're going to say I'm going
to say ah but people might get
symptomatic after they've already got
the infection and after they're already
shedding virus that may be true up to a
point but what we do know is that the
longer the infection goes on so the
maximum peak of the symptoms the
infectivity rises so therefore someone
who's not feeling very unwell
is they may well have virus recoverable
but they're probably not that infectious
so the chances of you encountering a
runner who breathed enough virus on you
for you to pick it up in the fresh open
air a very very slight so I wouldn't
worry about it I would I would
concentrate more on the enormous benefit
you're doing to your health through
getting some fresh air sunshine and
exercise and the advice to runners would
be be polite try and stay two metres
away yeah that's right exactly
okay here's one from Tim sands in
ross-on-wye on in Herefordshire
Elisabetta who says if the number of
tests being conducted rises logically
will the number of confirmed cases rise
equally what
why is so much important given to the
data I think yes we've just heard that
there is the possibility of of
asymptomatic patients and therefore
testing in a surveillance er setting so
without asking if people have symptoms
or not will actually be able to give us
that numbers about who is got the virus
even if they're there well but also
testing generally not only the people
who are presenting coming with us most
severe symptoms are requiring
hospitalizations or the healthcare
workers but also testing more widely in
the community will allow other to
discriminate to identify who has the
corona virus and who hasn't and
therefore not only we will have a much
more accurate idea of picture of how
much virus is circulating but there is
the potential there that we could start
targeting for example self-isolation to
only the people who we know are infected
so increasing a number of tests would be
you know the one set to determine if you
have an ongoing infections it's
extremely involved I'm interested just
maybe you could both give me an answer
and they said do you think antibody
testing is more important than antigen
or is it more important to isolate
people who are sick is that is that the
most important as far as you're both
concerned Chris well III think there are
two slightly different things that
answer to slightly different questions
at the moment antibody testing isn't
very useful and that's because very few
people have actually had the virus in
the grand scheme of things so far
because you make antibodies and you make
antibodies in appreciable amounts about
three or four weeks after you've cleared
the virus so actually at the moment as
we haven't had a very large number of
people who've actively been infected we
wouldn't be testing very many people and
returning positive so antibody tests
we've actually got time to wait a little
while before they become useful and they
will be very useful we're definitely
going to want them but what we need to
focus on right now is telling people
whether or not they really have this
virus and the people we need to
prioritize are the health care workers
because something like one in four
doctors and about one in five nurses are
currently affected they can't actually
get to their jobs or go to their jobs
because their self-quarantine
because they might have this infection
they probably don't have this infection
they probably have something else
because at the time they would have been
catching it we know that from the tests
we're doing in our laboratory only a few
probably about 10 percent of the tests
we were doing were actually positive for
coronavirus in the last week or so
that's really changed though in the last
week we've gone from small numbers of
tests positive - maybe now half the
tests we're doing returning positives so
the numbers in the community really have
lept up but that's why it's now getting
really valuable to be able to test
people who have the symptoms to see who
really does and who doesn't have it
because that will inform who can come to
work or not and look after the people
who really do have it okay it is better
do they fumigate the roads in Italy okay
because this next question sort of lost
on me I wasn't aware any company was
doing that but KP from London oh I'm
being told that China do this
KP from London says my question is why
aren't the government fumigating roads
with disinfectant sprays like other
countries are doing to prevent the
spread of the corona virus I think when
there is a large circulation of virus
and wild in the in the community
potentially it is the scene as a good
public health measure any intervention I
would have thought however they're
actually social distancing as self
isolation and cleaning those surfaces
where we do actually come in contact
because we touch them with our hands
like handles or you know if we have to
on public transports for examples or
Charlie said supermarkets doors actually
are the surfaces we need to specifically
look at I'm not sure how much actually
disinfecting an entire Road on the
tarmac but I do have to admit that I
tend to look at viruses from the
molecular point of view not when they
are on tarmac okay all right then here's
one Chris I would choose it it's puzzled
me actually from Edward picton how long
is the average time
from contracting Kovack Kovach 19 to
death actually occurring and therein
lies the rub with why this is proving
such a challenge to tackle because it's
a long time unlike the flu where you get
symptoms almost from one day after you
get the virus and then within five days
you're done and dusted the whole thing's
over
this thing it's only just getting going
by five days so the average incubation
time before people even have any
symptoms is five days it may be as long
as eleven days we're using 14 days as a
safety factor and then having actually
started to get symptoms people then
usually go along for about a week or so
feeling none specifically unwell maybe
their cough gets a bit worse they have
fevers and they feel not very well at
all at that point they either recover or
they then spend another week getting
worse at which point they may present to
medical services and then often it takes
another week before people get really
really unwell so the entire illness can
be very long and drawn-out or maybe
three weeks or so and we think there are
two phases to this we think that the
initial phase that first week or so is
the virus attacking your tissues and
teaching your immune system what it
looks like and we think the next phase
of the illness when people get very
severely unwell and may need to go into
hospital and may need to end up in
intensive care and may pass away that
seems to be an immune reaction to the
virus and that is your own body damaging
your own tissues and this is why we need
to learn a lot more about how this virus
makes us unwell because we need to know
how to intervene meaningfully and with
what sorts of drugs or what sorts of
treatments at what points in their
illness so so to put this very crudely
there are some bodies that overreact to
it a smaller percent a small percentage
because the vast majority of is recover
but some people just what every produce
a response within within the lungs and
within within the throat that's the
theory we don't know at the moment but
there are some tantalizing theories as
to why this might be happening one
suggestion is that because the corona
virus that we're seeing now is a member
of a big family of corona viruses it
could be that other members of the
corona virus which circulate and have
done for many years in humans and cause
common cold type symptoms if you've
caught one or more of those in the past
you may have educated your immune system
to
make certain places of antibodies which
when you encounter this new coronavirus
they stick to it they don't destroy it
or deactivate it they just make it
stickier so it's actually even more
attractive to your tissues and it finds
it easier to spread and make you unwell
and it may be that they're for people
who are older are more likely to have
encounter these are corona viruses and
that's why they are more likely to get
illah in addition to having other kinds
of pre-existing health problems younger
people on the other hand who haven't had
enough time in their life yet to
encounter so many of these other corona
viruses wouldn't have that and that
would explain why we get this age
dependent effect it's just a theory
there's no evidence to back it up apart
from anecdotal evidence at the moment
but it does sound reasonable it's
biologically plausible that could be
what's going on that's an interesting
segue Elisabetta took this next question
from Marian elder in Surrey who says
there was a report a few days ago that
having a flu jab may offer a degree of
immunity is there any evidence of this
and the likelihood of research into it
the flu virus and the corona viruses are
completely different viruses and there
is no cross protection that the flu jab
that can give against the corona virus
this doesn't mean however you know
absolutely do keep for getting the flu
jab especially in the current climate
because we can at least prevent
ourselves to become infected with the
flu and then we can concentrate our
resources on actually tackling the
corona virus but no I mean that I am not
familiar with the report itself but
there is no cross bridging protection
there which probably answers this next
question from less finding Colchester
maybe you could pick this up as well
Elisabetta I had the anti pneumonia
injection as soon as I turned 70 so I
wonder if it will still protect me from
the worst of the Kovach 19 effects so it
would not protect at all again directly
could be 19 the corona virus however
when it comes to potentially other
infection that can occur as the corona
virus enters as we cope with 19 since
some progress having had a jab against
some bacterial infection is a good thing
so again keep getting the job so that
you that are offered to you that are
available to you but unfortunately we do
not have a job now that allows us to
protect against these coronavirus but
lots of people are working on it and it
will come good here is the million
dollar question Chris from Karen glaive
ian harford sure can you catch this
virus again if you've already had it I'm
doubtful there have been some reports
circulating of people testing positive
or then testing negative and then
testing positive again I don't think
that that's people reacquiring the virus
some people have speculated that's the
case I think that's very unlikely I
think what's much more likely to be
happening is that the test is just not
very good we know that the test we're
all using do miss cases and that's
because this virus is very good at
growing in lung tissue it's much less
good at growing in nose and throat
tissue so when we take a swab from the
back of the throat we're often detecting
just trace amounts of virus very low
levels so it's possible to just swap the
wrong bit of the nose or throat you
might not pick up a threshold amount of
a detectable amount in other words a
virus there which is why when a person
is in the recovery phase and the amount
of virus and their body is dropping you
might pick it up one day test them again
oh it's negative now and then if you
look again you might find it again
you'll be very unlikely having developed
a strong immune response to clear it
from your body that you'd then catch it
again so soon so I think there's a
probably spurious reports probably the
immunity you make is going to be at
least for the short term robust and
resilient and you won't catch it again
just just on those tests that you say
you've seen where people think they've
had it again I mean it what's the false
negative statistic on that how many
people are we talking about well I can
actually speak from experience here
because we have had samples in our
laboratory where we have tested people
we have tested them and said they were
negative we then got further samples
about a week later from deep down in the
lungs in these people because by then
they had regrettably ended up in
intensive care and at that point we were
testing them as positive we then went
back and looked at using a different
test at the samples in the nose and
throat and we got a weak positive
showing that actually they had the virus
all along it's just that the test we're
using does miss results sometimes and
that's not nothing to do with our tests
nothing to do with the fact that we're
not doing our job properly nothing like
that it's purely because all
have gray areas where they miss some
cases and in this case if you're if
you're falling down the cracks between
the flagstones that can happen and
that's why it's so important that when
we use a test we use a very good test
which doesn't do that as often or does
that as least often as possible
Elisabetta michael robbins in richmond
us a fairly legitimate question why are
we not testing or quarantine people
arriving on flights from abroad I think
actually we recommendation from the UK
government and the FCO is actually
anybody who has to travel back
especially their British citizens that
need to be repatriated do have to self
isolated foot for seven days and in
terms of testing again it goes back to
what Chris has explained so at the
moment we are testing symptomatic
patients who needs admission at hospital
and also health care workers those have
been given the priorities or so if
people have been allowed to travel it's
very likely most likely that today do
not have any symptoms and and they are
well and so just as precautions they
absolutely need to sell to isolate but
the testing it's probably not a priority
right now this next question interest me
Chris because I think there'd be a lot
of people who might have had an instance
like this it comes from rosemary Wallace
in Welwyn Garden City Welling garden
city I should say after seven days of
quarantine with no testing what happens
if you get another period of raised
temperature my husband is worried about
his job in a shop so clearly someone
there is self isolated for seven days
and then wants to get back to work but
maybe still has a temperature hi rose
right the bottom line here is and
actually I can recommend the
government's NHS web page is very very
good illness and explains it very
clearly so thumbs up to them for that
what they say is if you fit the case
definition so you have a new cough and
you have a fever 37.8 and above etc and
this goes on for you know it's not just
a one-off thing it's a new cough it's a
persistent cough then you should self
isolate now at the end of that period of
isolation if your cough is still there
it's not a problem but if your because
coughs often persist for a while
afterwards but if you're still having
temperatures like viruses at the moment
and I
is gonna be okay then actually you
should at that stage not the isolate
yourself you should regard yourself as
potentially still symptomatic then the
next question becomes okay I recover now
I feel better what do I do if it happens
again well the thing is we don't know at
the moment whether that episode was
coronavirus or just one of the other
very common respiratory infections that
are going around at the moment that
caused the temperature in a cough so
you're back to square one and you need
to realize let yourself for another
period of seven days or until your fever
has gone away I've learned so much we're
out of questions we will have many more
I know because there are hundreds of
questions coming in to us at the BBC but
doctor Chris Smith and dr. Elizabeth
Elisabetta Grappelli thank you so much
indeed thank you I'm finished thank you
both
[Music]
you
[Music]