(bright music)
- I would like to speak to you today about vaccines,
both as one who has studied and taught immunology
for most of my adult life.
And as a citizen of the world.
My interest in vaccine acceptance was peaked
when I found that some of my daughter's friends
were reluctant to vaccinate their children.
In fact, one of them contracted measles
on her honeymoon in Italy
having not previously been vaccinated.
At the same time the Los Angeles Times
published an online database
showing the percentage of students with measles, mumps,
and rubella vaccination at each elementary school
in the Los Angeles Area.
And I found that the school
to which my grandchildren belonged or attended,
had only a 65% prevalence of MMR vaccination.
So after several years of thinking
and writing about the problem of vaccine coverage,
I came to understand it from several points of view.
And the first is that,
we human beings are the most diseased species on earth.
And this comes not from some way of knowing
the extent of disease for every species in existence,
but rather understanding the epidemiology
and recent human history.
Our history over the last two to 3000 years
has included one epidemic after another.
Epidemics that often killed 25% or more of the population
in any given region of the world,
and lasted decades or sometimes even centuries.
But even this is a great underestimate
of the effects of epidemic disease on human history.
Since the dawn of history,
we have been continually plagued
by what Jared diamond called "Crowd Epidemic Diseases".
Until the latter part of the 20th century,
most families lost children to smallpox,
scarlet fever, pertussis.
There were birth defects caused by rubella.
Occasionally children died from measles
and other parts of the world malaria still kills
about 400,000 people per year, mostly children.
This sort of epidemic disease was continuous
for at least two millennia.
Many more people died of these diseases
than all the wars combined.
And the question is why.
We're exceptionally intelligent as human beings,
but why are we as a species exceptional
with respect to the loss of life due to infectious disease?
And the answer is in a very short span of time,
we human beings completely changed our ecology.
We evolved as small dispersed communities
of hunter gatherers,
consisting of a few hundred individuals.
But with time, we domesticated plants and animals,
and eventually people became situated
and lived in permanent communities of much higher density.
At the same time,
we sampled all of the infectious agents to be found
in cows and sheep and horses and goats and birds.
Meaning we captured many infectious diseases
from these animals.
Infectious diseases that were not evolved
or if you will tune to human beings.
So how does this affect infectious diseases
in the modern world?
So this is a short version of what we call
human disease ecology.
And the first point is that pathogens found
in low density populations
are long-lasting and exhibit low or infrequent tolerance.
That is they exhibit low disease.
You can imagine that this is
because a pathogen that is too virulent
would kill its host before it can be transmitted
to the next host.
And in low density populations,
it takes a long time for diseases to be transferred
from one person to another.
Conversely, in high density populations,
pathogens are able to be transmitted rapidly
from host to host.
And so there's no selection pressure to keep hosts mobile
or even alive.
And one metaphor for this could be a forest
and the possibility of a forest fire.
So, if we consider an isolated stand of trees
in a green meadow,
this would pose no danger of a raging fire.
Just as an isolated band of hunter gatherers
posed no danger for a large scale epidemic.
Whereas for a dense interconnected forest,
one spark can ignite a holocaust,
causing widespread damage that lasts a long, long time.
Another point is that zoonoses
are infectious agents that jump from one species to another.
And as their virulence is unpredictable
because they haven't co-evolved with their host,
zoonoses are very dangerous.
And examples being Ebola virus, Lassa fever, Hunter virus.
They jump into the human population.
Oftentimes they only infect a few hundred people
or a few dozen people.
And then they fade out of the population.
And this was the case for Ebola virus until about 2014,
where it evolved to be more infectious.
And so now it can cause epidemics.
And the concept is that we human beings
are not only culturally connected or genetically connected.
Human beings worldwide are biologically connected,
in the present, through our exchange of infectious agents
and our common susceptibility to disease.
We are more than simply individuals
coexisting on the same planet.
We are all hosts within a disease network
of microbes and viruses.
For example, as long as one person on earth
harbored variola virus,
which is the cause of smallpox,
billions of people,
the entire population of the world was at risk.
Infectious diseases show the real world consequences
of individual actions on the community of humankind.
So, let's visualize this schematically.
This is what the world looks like
presently in the COVID-19 pandemic.
Most people have not encountered the virus.
Of the, almost 8 billion people on earth,
most have not contracted the disease.
There are people, the ones in red, that are infectious.
And then there are a few people who have had the disease
and we hope they are immune.
We don't know that yet
but we're hoping that this is the case.
Now, one way that this could end
would be after a decades-long pandemic,
in which you might argue that you could encounter
herd immunity, that is,
most people have had the disease
and they are now immune and the disease starts to die out.
Of course, it doesn't die out completely
because there's always an influx of susceptible new hosts
in the form of newborn children.
And so this is how diseases typically go
from being epidemic diseases,
to being childhood diseases.
Where most everyone gets the disease as a child
and either dies or becomes immune.
Now just yesterday,
the Director General of the World Health Organization
was quoted as saying,
"Never in the history of public health,
has herd immunity been used as a strategy
for responding to an outbreak."
So, rather than waiting for a decades-long epidemic
for this to decrease,
we need a vaccine and we need an effective vaccine.
So let me just go over very quickly
what the types of vaccines there are
and what types are being developed for COVID-19.
The three types of vaccines
that are currently licensed in the United States
are whole inactivated virus,
live attenuated virus,
and subunit vaccines.
The whole inactivated virus is similar to that
that was developed by Salk for the polio virus.
And it is a virus that is grown.
It's the wild type virus,
but it's inactivated chemically usually with formalin.
On the other hand,
a live attenuated virus is an actual live growing virus
but it's been selected so that it doesn't cause disease.
And examples of that are the MMR virus,
the sabin vaccine, vaccine for shingles virus,
vaccines like that.
And the third type is the subunit vaccine
in which you make a protein that comes from the virus,
usually by recombinant DNA techniques.
And you add to that something called an adjuvant.
Now, what's been occurring over the last few years,
and now it's been accelerated at warp speed we're told,
are the development of new types of vaccines.
One of them is to use recombinant viral vectors.
These are vaccines in which a innocuous virus,
perhaps adenovirus has been genetically modified
to encode one little part of the SARS-CoV-2 virus.
And so, an individual would be infected with the adenovirus
and make an immune response that would include
an immune response to this portion of the COVID-19
or the SARS-CoV-2 virus.
Another is to use DNA or RNA directly that's encapsulated
usually with lipid nanoparticle.
This type of a vaccine then turns your own cells
into a factory for producing viral products,
and then your immune system responds.
What all of these vaccines have in common
is the ability to provoke an inflammatory response,
which is redness, swelling, heat, a little bit of pain.
And this is actually needed to initiate
a production of long-lasting immunity.
None of these agents are intrinsically toxic,
but the temporary discomfort that they produce
is the result of the onset of an immune response.
When your arm is sore after an influenza vaccination,
that's because your immune response is actually working.
And finally, for this, we can, again, rely on
Anthony Fauci, who said that,
"Finding an effective vaccine to prevent the infection
with SARS-CoV-2 is an urgent public health priority."
So, once we make a vaccine,
how do we know it is safe?
Well, there are a lot of means and place to ensure for this.
And the first is,
that the Food and Drug Administration analyzes
the clinical data to ensure that there is safety.
And in clinical trials for vaccines
typically include tens of thousands of patients,
half of whom get a placebo
and half of whom get the vaccine.
And both the safety and efficacy of the vaccine under study
is then analyzed.
It's only when that is determined to be safe
is it then released for general public vaccination.
Most of the time.
Most of the potential for clinical adverse effects
are found at this stage
before it ever gets to general public vaccination.
Next, the CDC, the Center for Disease Control and Prevention
and the FDA maintain a nationwide monitoring system
called the "Vaccine Adverse Event Reporting System",
which allows anyone to report an adverse reaction
either online, by fax, or by mail.
Probably the fax is a little outdated at this point,
but by online or by mail.
There's also a program that's carried on
between the CDC and US Healthcare organizations
that track the data for millions of people
who receive vaccines
and then are monitored for their health.
And finally, there's the National Vaccine
Injury Compensation Program,
which receives reports of adverse vaccine reactions,
studies each claim,
and then decides whether or not there's the possibility
that an adverse reaction occurred based on vaccination.
So for example, from 2006 to 2018,
over 3.7 billion doses of COVID vaccines
were distributed in the United States.
There were 7,400 petitions for adverse reactions
and 5,000 were compensated.
So about one in a million vaccine dose
results in a compensated adverse reaction.
For measles, mumps, and rubella,
there were about 108 million doses administered.
And from those 108 million doses,
259 adverse reactions were filed
and 128 were compensated.
Again, about one in a million doses
results in an actual adverse reaction.
So let me close by saying that
our modern interconnected densely populated world
is only possible,
because of large scale vaccine programs.
The difficulty is that as we approach herd immunity
in a region,
everyone is protected.
And thus there's a tendency to feel
that vaccination is unnecessary.
But I want to say that we remain protected
only if the vast majority of the population
realizes the importance of community participation
in our common immunity to disease.
So thank you very much for your attention.
(bright music)