So, that would suggest that the
vaccine efficacy was excellent.
What is vaccine efficacy?
It is, the degree to which a vaccine prevents
disease and potentially also transmission,
so, preventing infectivity is important,
under ideal or controlled circumstances.
Typically, one creates an estimate
of the efficacy of any intervention,
whether it's in this case a vaccine
or medication or something similar,
by comparing that that test
group, the vaccinated group,
with a placebo group,
so, efficacy is how well it prevents disease
and potentially transmission disease.
That's what's predicted in a
or a can a clinical study in
which everything is controlled.
What about real world or population level
This is what is known as
the effectiveness estimate.
This is how well in this case the vaccine
actually performs in the real world.
As you would imagine,
that the real world numbers are going to be
than the carefully controlled efficacy numbers.
But that's okay, as long as
the effectiveness is adequate.
What one is really looking for of course,
how effective is the intervention
the vaccine against infection?
does it do its job in the real world setting
and this is the number the
effectiveness against infection,
that the FDA signed, an a hoped for value
As it turns out that that target
was exceeded significantly,
by most vaccine products currently available,
in the United States and Europe
and even parts of India and Africa.
So, most vaccines are up to 90%
effective against symptomatic infection,
so, that is fantastic.
And of course, on a personal level
one wants a product a vaccine which
will protect one from infection period.
However, in terms of major use of resources,
the absolute morbidity, the challenge
that all countries have faced,
in the COVID-19 pandemic,
has been the burden on health care infrastructure,
so, what one really wants
to prevent that challenge,
is, effectiveness against severe disease.
How well does the vaccine do against a disease,
which requires, the patient to be hospitalized
and to consume health care resources
and of course, this is the most important
not just to prevent death, which is ideal,
but also prevent use of the healthcare system.
And again, major vaccines,
certainly the messenger RNA vaccines
and several of the adenovirus vector vaccines,
are near or at 100% effectiveness
against severe disease, that's fantastic.
Okay, let's fast forward into
the real world, one more step
and that is knowing that as we attempt
to control, the SARS-Coronavirus II
in nature, nature abhors
a vacuum and new variants,
mutations are occurring all the time.
How well do the vaccines do,
in effectiveness against the new virus variants?
Most of the vaccines do
better against severe disease,
even against the variants,
but all of them have at least some protection,
even as low as 50% against
the new variants of concern.
As we speak, however, surveillance
on goes all across the world
and new vaccines are still in development,
so, any slide regarding this
is likely going to be dated,
by the time you're watching it.
Now, vaccines are fantastic, but
they are also an intervention,
a medical science intervention
and so there will be side effects,
most of which are minor.
So, the minor side effects identified
with the vaccines noted so far,
are, a flu-like illness, soreness
at the injection site of course,
which, will last a couple days to a week
and accompanied sometimes by malaise,
low-grade fevers, some sore muscles
and that basically reflects a
very excellent immune response,
by the vaccine recipients.
Thankfully, major side effects
and certainly fatal side effects
have been incredibly rare,
that's a wonderful thing and that
of course then drives the question,
was that incredibly rare, “I
hadn't seen it before side effect,”
in my single vaccine
recipient, due to the vaccine,
or was it something related to health issues,
pre-existing in the vaccine recipient
and in many cases it's very difficult to tell,
as proof of causality is difficult to achieve.
So, as an example there have been
evidence episodes of myocarditis,
in vaccine recipients of one
of the messenger RNA vaccines,
in vaccine recipients of one
of the messenger RNA vaccines,
Pfizer or Moderna, mostly young men
and those incidence, numbers of myocarditis,
in those individuals have exceeded
the rate normally witnessed,
in a non-vaccine, non-covid pandemic time.
So, that would suggest that
there is some association,
why we don't know, but some association,
with messenger RNA vaccination and
myocarditis, in certain individuals.
So, what are the side
effects that we've witnessed,
anaphylaxis, of course, would
be a severe side effect,
anaphylaxis is possible with any vaccine.
Fortunately, for the messenger RNA vaccines,
in which some episodes have been reported,
this is an incredibly low incident,
so just 3 to 5 per million vaccine recipients,
mostly in women who had pre-existing
severe environmental allergies
or allergies to food or other products.
The incidence of thrombosis and thrombocytopenia
and specifically, a
vaccine-induced immune thrombocytopenia,
has been demonstrated in patients who received
of the adenovirus vectored
vaccines mostly AstraZeneca
and Johnson and Johnson.
These individuals, have had some
significant effects of this thrombosis,
including cerebral venous thrombosis
and splanchnic vein thrombosis,
are the two most common, thrombotic
illnesses witnessed in these individuals.
With the AstraZeneca vaccine, out
of 34 million doses administered,
you can see the numbers there, just 169
episodes of cerebral venous thrombosis
and 53 episodes of splanchnic vein
thrombosis, have been demonstrated
and confirmed with 18 deaths and based on
although it is an incredibly rare
risk, but the risk is felt to be real.
So, in many countries, AstraZeneca,
is not given to vaccine recipients,
who are under age 60,
because these cerebral venous
and splanchnic venous thrombotic events,
all occurred in young adults.
In the Johnson and Johnson vaccine,
out of 20 million doses administered,
25 cases and 9 deaths respectively,
with vaccine associated
So, if we then try and compare
the risk of vaccine effects,
whether they're minor or major or severe or
to other adverse effects, these are
great these are great talking points,
if one is having this
conversation with one's patients,
the lifetime chance of dying
in a motor vehicle accident,
1 in 103 that's huge.
The lifetime chance of getting struck by
lightning 1 in 15,300 and 10% of those die.
So, one is absolutely going to be
encountering a lot of vaccine hesitancy,
due to the side effects, but the risks of
death from COVID-19 itself, are far greater,
than any theoretical risk from vaccine
and one can also use these lifetime risks