The power of herd immunity
-
0:00 - 0:05One of the first patients
I had to see as a pediatrician was Sol, -
0:05 - 0:08a beautiful month-old baby
-
0:08 - 0:12who was admitted with signs
of a severe respiratory infection. -
0:12 - 0:16Until then, I had never seen
a patient worsen so fast. -
0:17 - 0:20In just two days
she was connected to a respirator -
0:20 - 0:23and on the third day she died.
-
0:23 - 0:25Sol had whooping cough.
-
0:25 - 0:30After discussing the case in the room
and after a quite distressing catharsis, -
0:30 - 0:33I remember my chief resident said to me,
-
0:33 - 0:36"Okay, take a deep breath. Wash your face.
-
0:36 - 0:39And now comes the hardest part:
-
0:39 - 0:41We have to go talk to her parents."
-
0:42 - 0:46At that time, a thousand questions
came to mind, -
0:46 - 0:50from, "How could a one-month-old
baby be so unfortunate?" -
0:51 - 0:54to, "Could we have done
something about it?" -
0:55 - 0:58Before vaccines existed,
-
0:58 - 1:03many infectious diseases
killed millions of people per year. -
1:03 - 1:07During the 1918 flu pandemic
-
1:07 - 1:1050 million people died.
-
1:10 - 1:13That's greater than Argentina's
current population. -
1:13 - 1:17Perhaps, the older ones among you
remember the polio epidemic -
1:17 - 1:20that occurred in Argentina in 1956.
-
1:20 - 1:24At that time, there was no vaccine
available against polio. -
1:24 - 1:26People didn't know what to do.
They were going crazy. -
1:26 - 1:28They would go painting trees
with caustic lime. -
1:28 - 1:30They'd put little bags of camphor
-
1:30 - 1:33in their children's underwear,
as if that could do something. -
1:34 - 1:39During the polio epidemic,
thousands of people died. -
1:39 - 1:43And thousands of people were left
with very significant neurological damage. -
1:45 - 1:47I know this because I read about it,
-
1:47 - 1:51because thanks to vaccines,
my generation was lucky -
1:51 - 1:54to not live through an epidemic
as terrible as this. -
1:54 - 1:59Vaccines are one of the great successes
of the 20th century's public health. -
1:59 - 2:01After potable water,
-
2:01 - 2:05they are the interventions
that have most reduced mortality, -
2:05 - 2:07even more than antibiotics.
-
2:08 - 2:13Vaccines eradicated terrible diseases
such as smallpox from the planet -
2:13 - 2:16and succeeded in significantly
reducing mortality -
2:16 - 2:18due to other diseases such as measles,
-
2:18 - 2:22whooping cough, polio and many more.
-
2:22 - 2:29All these diseases are considered
vaccine-preventable diseases. -
2:30 - 2:32What does this mean?
-
2:32 - 2:35That they are potentially preventable,
-
2:35 - 2:38but in order to be so,
something must be done. -
2:38 - 2:40You need to get vaccinated.
-
2:40 - 2:44I imagine that most,
if not all of us here today, -
2:44 - 2:47received a vaccine
at some point in our life. -
2:49 - 2:53Now, I'm not so sure that many of us know
-
2:53 - 2:57which vaccines or boosters
we should receive after adolescence. -
2:59 - 3:03Have you ever wondered
who we are protecting -
3:03 - 3:05when we vaccinate?
-
3:05 - 3:07What do I mean by that?
-
3:07 - 3:12Is there any other effect
beyond protecting ourselves? -
3:13 - 3:15Let me show you something.
-
3:16 - 3:18Imagine for a moment
-
3:18 - 3:20that we are in a city
-
3:20 - 3:23that has never had a case
of a particular disease, -
3:23 - 3:25such as the measles.
-
3:25 - 3:30This would mean that no one in the city
has ever had contact with the disease. -
3:30 - 3:35No one has natural defenses against,
nor been vaccinated against measles. -
3:36 - 3:40If one day, a person sick with the measles
appears in this city -
3:41 - 3:45the disease won't find much resistance
-
3:45 - 3:47and will begin spreading
from person to person, -
3:47 - 3:52and in no time it will disseminate
throughout the community. -
3:52 - 3:54After a certain time
-
3:54 - 3:57a big part of the population will be ill.
-
3:58 - 4:02This happened when there were no vaccines.
-
4:03 - 4:07Now, imagine the complete opposite case.
-
4:07 - 4:10We are in a city
-
4:10 - 4:13where more than 90 percent
of the population -
4:13 - 4:15has defenses against
the measles, which means -
4:15 - 4:19that they either had the disease,
survived, and developed natural defenses; -
4:19 - 4:23or that they had been
immunized against measles. -
4:23 - 4:25If one day,
-
4:25 - 4:29a person sick with the measles
appears in this city, -
4:29 - 4:33the disease will find much more resistance
-
4:33 - 4:36and won't be transmitted
that much from person to person. -
4:37 - 4:40The spread will probably remain contained
-
4:41 - 4:44and a measles outbreak won't happen.
-
4:45 - 4:48I would like you
to pay attention to something. -
4:49 - 4:51People who are vaccinated
-
4:51 - 4:54are not only protecting themselves,
-
4:54 - 4:58but by blocking the dissemination
of the disease -
4:58 - 5:00within the community,
-
5:00 - 5:04they are indirectly protecting
the people in this community -
5:04 - 5:06who are not vaccinated.
-
5:07 - 5:10They create a kind of protective shield
-
5:10 - 5:13which prevents them from
coming in contact with the disease, -
5:13 - 5:15so that these people are protected.
-
5:17 - 5:20This indirect protection
-
5:20 - 5:23that the unvaccinated people
within a community receive -
5:23 - 5:27simply by being surrounded
by vaccinated people, -
5:28 - 5:31is called herd immunity.
-
5:33 - 5:36Many people in the community
-
5:36 - 5:39depend almost exclusively
on this herd immunity -
5:39 - 5:42to be protected against disease.
-
5:43 - 5:47The unvaccinated people you see
in infographics are not just hypothetical. -
5:47 - 5:51Those people are our nieces
and nephews, our children, -
5:51 - 5:54who may be too young
to receive their first shots. -
5:55 - 5:57They are our parents, our siblings,
-
5:57 - 5:59our acquaintances,
-
5:59 - 6:01who may have a disease,
-
6:01 - 6:04or take medication
that lowers their defenses. -
6:06 - 6:10There are also people who are
allergic to a particular vaccine. -
6:11 - 6:14They could even be among us,
-
6:14 - 6:16any of us who got vaccinated,
-
6:16 - 6:19but the vaccine didn't produce
the expected effect, -
6:19 - 6:24because not all vaccines
are always 100 percent effective. -
6:24 - 6:29All these people depend
almost exclusively on herd immunity -
6:29 - 6:31to be protected against diseases.
-
6:32 - 6:37To achieve this effect of herd immunity,
-
6:37 - 6:42it is necessary that a large percentage
of the population be vaccinated. -
6:42 - 6:46This percentage is called the threshold.
-
6:46 - 6:49The threshold depends on many variables:
-
6:49 - 6:52It depends on the germ's characteristics,
-
6:52 - 6:56and those of the immune response
that the vaccine generates. -
6:56 - 6:58But they all have something in common.
-
6:58 - 7:04If the percentage of the population
in a vaccinated community -
7:04 - 7:07is below this threshold number,
-
7:07 - 7:11the disease will begin
to spread more freely -
7:11 - 7:16and may generate an outbreak
of this disease within the community. -
7:16 - 7:23Even diseases which were
at some point controlled may reappear. -
7:25 - 7:27This is not just a theory.
-
7:27 - 7:29This has happened,
and is still happening. -
7:31 - 7:36In 1998, a British researcher
published an article -
7:36 - 7:39in one of the most important
medical journals, -
7:39 - 7:41saying that the MMR vaccine,
-
7:41 - 7:44which is given for measles,
mumps and rubella, -
7:44 - 7:46was associated with autism.
-
7:46 - 7:48This generated an immediate impact.
-
7:49 - 7:54People began to stop getting vaccinated,
and stopped vaccinating their children. -
7:54 - 7:55And what happened?
-
7:55 - 7:58The number of people vaccinated,
-
7:58 - 8:02in many communities around the world,
fell below this threshold. -
8:02 - 8:06And there were outbreaks of measles
in many cities in the world -- -
8:06 - 8:08in the U.S., in Europe.
-
8:08 - 8:10Many people got sick.
-
8:10 - 8:13People died of measles.
-
8:14 - 8:15What happened?
-
8:15 - 8:19This article also generated a huge stir
within the medical community. -
8:20 - 8:24Dozens of researchers began to assess
if this was actually true. -
8:25 - 8:28Not only could no one find
-
8:28 - 8:34a causal association between MMR
and autism at the population level, -
8:34 - 8:39but it was also found that this article
had incorrect claims. -
8:39 - 8:41Even more, it was fraudulent.
-
8:42 - 8:45It was fraudulent.
-
8:45 - 8:52In fact, the journal publicly retracted
the article in 2010. -
8:53 - 8:57One of the main concerns and excuses
for not getting vaccinated -
8:57 - 8:59are the adverse effects.
-
9:00 - 9:05Vaccines, like other drugs,
can have potential adverse effects. -
9:06 - 9:08Most are mild and temporary.
-
9:08 - 9:14But the benefits are always greater
than possible complications. -
9:16 - 9:20When we are ill,
we want to heal fast. -
9:20 - 9:22Many of us who are here
-
9:22 - 9:26take antibiotics
when we have an infection, -
9:26 - 9:29we take anti-hypertensives
when we have high blood pressure, -
9:29 - 9:31we take cardiac medications.
-
9:31 - 9:35Why? Because we are sick
and we want to heal fast. -
9:35 - 9:37And we don't question it much.
-
9:37 - 9:41Why is it so difficult
to think of preventing diseases, -
9:42 - 9:45by taking care of ourselves
when we are healthy? -
9:45 - 9:48We take care of ourselves a lot
when affected by an illness, -
9:48 - 9:51or in situations of imminent danger.
-
9:52 - 9:55I imagine most of us here,
-
9:55 - 9:59remember the influenza-A pandemic
-
9:59 - 10:02which broke out in 2009
in Argentina and worldwide. -
10:02 - 10:06When the first cases
began to come to light, -
10:06 - 10:09we, here in Argentina,
were entering the winter season. -
10:10 - 10:12We knew absolutely nothing.
-
10:12 - 10:14Everything was a mess.
-
10:14 - 10:19People wore masks on the street,
ran into pharmacies to buy alcohol gel. -
10:19 - 10:22People would line up
in pharmacies to get a vaccine, -
10:22 - 10:25without even knowing
if it was the right vaccine -
10:25 - 10:27that would protect them
against this new virus. -
10:27 - 10:30We knew absolutely nothing.
-
10:30 - 10:34At that time, in addition to doing
my fellowship at the Infant Foundation, -
10:35 - 10:39I worked as a home pediatrician
for a prepaid medicine company. -
10:40 - 10:43I remember that I started
my shift at 8 a.m., -
10:43 - 10:47and by 8, I already had a list
of 50 scheduled visits. -
10:47 - 10:50It was chaos;
people didn't know what to do. -
10:51 - 10:55I remember the types of patients
that I was examining. -
10:56 - 11:00The patients were a little older than
what we were used to seeing in winter, -
11:00 - 11:02with longer fevers.
-
11:02 - 11:06And I mentioned that
to my fellowship mentor, -
11:06 - 11:10and he, for his part, had heard
the same from a colleague, -
11:10 - 11:12about the large number
of pregnant women -
11:12 - 11:14and young adults
-
11:14 - 11:16being hospitalized in intensive care,
-
11:16 - 11:19with hard-to-manage clinical profiles.
-
11:21 - 11:27At that time, we set out to understand
what was happening. -
11:27 - 11:30First thing Monday morning,
we took the car -
11:30 - 11:33and went to a hospital
in Buenos Aires Province, -
11:33 - 11:39that served as a referral hospital
for cases of the new influenza virus. -
11:39 - 11:42We arrived at the hospital;
it was crowded. -
11:42 - 11:45All health staff were dressed
in NASA-like bio-safety suits. -
11:45 - 11:48We all had face masks in our pockets.
-
11:48 - 11:50I, being a hypochondriac,
didn't breathe for two hours. -
11:50 - 11:54But we could see what was happening.
-
11:54 - 11:57Immediately, we started
reaching out to pediatricians -
11:57 - 12:01from six hospitals in the city
and in Buenos Aires Province. -
12:01 - 12:05Our main goal was to find out
-
12:05 - 12:09how this new virus behaved
in contact with our children, -
12:09 - 12:11in the shortest time possible.
-
12:11 - 12:14A marathon work.
-
12:14 - 12:17In less than three months,
-
12:17 - 12:23we could see what effect
this new H1N1 virus had -
12:23 - 12:29on the 251 children
hospitalized by this virus. -
12:30 - 12:34We could see which children
got more seriously ill: -
12:34 - 12:37children under four, especially those
less than one year old; -
12:37 - 12:40patients with neurological diseases;
-
12:40 - 12:43and young children
with chronic pulmonary diseases. -
12:43 - 12:48Identifying these at-risk groups
was important -
12:48 - 12:51to include them as priority groups
-
12:51 - 12:54in the recommendations
for getting the influenza vaccine, -
12:54 - 12:56not only here in Argentina,
-
12:56 - 13:00but also in other countries
which the pandemic not yet reached. -
13:01 - 13:02A year later,
-
13:02 - 13:08when a vaccine against the pandemic
H1N1 virus became available, -
13:08 - 13:10we wanted to see what happened.
-
13:10 - 13:13After a huge vaccination campaign
-
13:13 - 13:18aimed at protecting at-risk groups,
-
13:18 - 13:25these hospitals, with 93 percent
of the at-risk groups vaccinated, -
13:25 - 13:29had not hospitalized a single patient
-
13:29 - 13:31for the pandemic H1N1 virus.
-
13:31 - 13:34(Applause)
-
13:36 - 13:40In 2009: 251.
-
13:41 - 13:44In 2010: zero.
-
13:44 - 13:49Vaccination is an act
of individual responsibility, -
13:49 - 13:53but it has a huge collective impact.
-
13:55 - 13:59If I get vaccinated,
not only am I protecting myself, -
13:59 - 14:03but I am also protecting others.
-
14:04 - 14:06Sol had whooping cough.
-
14:08 - 14:10Sol was very young,
-
14:10 - 14:14and she hadn't yet received
her first vaccine against whooping cough. -
14:15 - 14:19I still wonder what would have happened
-
14:19 - 14:25if everyone around Sol
had been vaccinated. -
14:26 - 14:28(Applause)
- Title:
- The power of herd immunity
- Speaker:
- Romina Libster
- Description:
-
How do vaccines prevent disease — even among people too young to get vaccinated? It's a concept called "herd immunity," and it relies on a critical mass of people getting their shots to break the chain of infection. Health researcher Romina Libster shows how herd immunity contained a deadly outbreak of H1N1 in her hometown. (In Spanish with subtitles.)
- Video Language:
- Spanish
- Team:
- closed TED
- Project:
- TEDTalks
- Duration:
- 14:41
Helene Batt edited English subtitles for El poder de la inmunidad colectiva | ||
Cynthia Betubiza edited English subtitles for El poder de la inmunidad colectiva | ||
Morton Bast edited English subtitles for El poder de la inmunidad colectiva | ||
Morton Bast edited English subtitles for El poder de la inmunidad colectiva | ||
Morton Bast edited English subtitles for El poder de la inmunidad colectiva | ||
Morton Bast edited English subtitles for El poder de la inmunidad colectiva | ||
Morton Bast edited English subtitles for El poder de la inmunidad colectiva | ||
Camille Martínez edited English subtitles for El poder de la inmunidad colectiva |