When, and if, a vaccine is announced, this will not be
the end, but the beginning
A vaccine for
coronavirus will not change the world immediately
High hopes in a vaccine can lead to resistance to simple
strategies that can reduce transmission.
Carolyn Y.
Johnson/The Washington Post 6 de Agosto de 2020, 14:56
In the collective
imagination, the arrival of a coronavirus vaccine seems imminent: it is the
happy ending to Hollywood for a depressing and harrowing daily life in a
pandemic.
Public health
experts, however, discuss a new concern: that hope for a vaccine may be
becoming too high. The confident narrative of politicians and businesses that a
vaccine is imminent could give people unrealistic beliefs about how quickly the
world can return to normal and could lead to resistance to simple strategies
that can reduce transmission and save lives in the short term.
Two coronavirus
vaccines entered the final stages of human testing in the last week of July, a
record for scientific speed that led leading government health officials to use
words like "historic" and "amazing." At the U.S. Congress
in July, pharmaceutical executives predicted that vaccines could be available
as early as October, or before the end of the year.
As the plot
progresses, so do expectations: if people manage to get away with it for a few
more months, the vaccine will arrive, the pandemic will end and everyone can
throw away their masks. But the best scenarios have not materialized throughout
this pandemic, and experts – who fully believe in the power of vaccines –
predict a long way to go.
"It seems
unlikely to me that the vaccine is a switch to turn off or a button to restart,
and we go back to pre-pandemic times," said Yonatan Grad, assistant
professor of infectious diseases and immunology at Harvard University's School
of Public Health. Or, as Columbia University virologist Angela Rasmussen says,
"It's not like we're going to land in the Land of Oz."
The announcement
that a vaccine has proved safe and effective will be a beginning, not the end.
Setting in motion to make a vaccine available to the people of the United
States and the world will test and put pressure on distribution networks,
supply chains, public trust and global cooperation. It will take months or,
more likely, years to reach a number of enough people to make the world safe.
For those who
take the vaccine as soon as it is available, protection will not be immediate –
it takes weeks for the immune system to form antibody platoons. And many
vaccine-associated technologies may require a second take weeks after the first
to increase immune defenses.
Immunity may be
short-lived or partial, requiring repeated boosters that overload the delivery
of vaccines or require people to maintain social distance and wear masks, even
after receiving the vaccine. And if a vaccine works worse for some groups of
people, if sections of the population are reluctant to take it, or if there
aren't enough doses circulating, some people will continue to get sick, even
after scientists declare victory over a vaccine – which could fuel a false
sense that it doesn't work.
A proven vaccine
will profoundly change the world's relationship with the new coronavirus and
that's how many experts believe the pandemic will end. In the popular
imagination, a vaccine is seen as a magical solution. But the truth –
especially with the latest vaccines – will probably have much more nuances.
Public health experts fear this could lead to disappointment and a delicate
confidence that is essential for the effort to beat the virus to succeed.
The effort to
develop vaccines is often described as a race, with a country or a company
ahead. The metaphor of the race suggests that what matters is who arrives
first. But the first to cross the line is not necessarily the best – and it is
almost certain that it is not the end of the race, which can last for years.
"The most
realistic scenario is likely to be like what we saw with HIV/AIDS," said
Michael Kinch, an expert in drug development and research at the University of
Washington in St. Louis. "With HIV now looking back, we had a very
mediocre first generation of medicines. I'm afraid – and people don't like to
hear this, but I keep nailing it – that we have to prepare ourselves for the
idea of not having a very good vaccine. My guess is that the first generation
of vaccines can be mediocre."
Vaccination day
On 12 April 1955,
a polio vaccine proved effective and safe. The creator, Jonas Salk, became a
national hero. Church bells rang, and people took to the streets to hug, said
Howard Markel, a historian at the University of Michigan.
But there were
obstacles along the way as scientists and public health officials tried to stop
a disease that was a major threat to children. The 'Cutter incident' became an
infamous moment in medicine when one of the vaccine's suppliers failed to
complete the virus's deactivation in the injection, infecting about 40,000
children, paralyzing 51 and killing five. These infections generated their own
epidemic, paralyzing 113 more and killing five more people.
"What's
amazing is that it was just a temporary problem," Markel said. "The parents
had so much confidence in the doctors and scientists, that everything went on,
people took the injections."
The vaccination
allowed by Salk was a transformative moment, but it did not mean the end of
polio. For two years, cases in the United States dropped by 80%, but outbreaks
continued for several years, even with the introduction of the vaccine. Six
years later, an oral polio vaccine was introduced that could be given as a
sugar cube that dissolved into the children's tongue. Polio was eliminated from
the United States in 1979.
But the polio
vaccine appeared at a different time in America's history, Markel said, when
people had great confidence that scientists, medical institutions and
government could change their lives for the better. In the case of coronavirus,
a small setback – a failure to communicate about vaccines, an unpleasant side
effect, a long-awaited candidate who fails large clinical trials or a vaccine
that is only partially protective – can have rampant effects, especially when anti-vaccine
activists are already sowing mistrust.
Anthony Fauci,
director of the National Institute of Allergies and Infectious Diseases, told
Congress on July 31 that he was "cautiously optimistic" that an
ongoing clinical trial of 30,000 people in phase III will produce a safe
vaccine. But there has been little talk about how to reflect on failures, even
if they are an inevitable part of science.
"What
happens if some of them fail phase III of the trial – will people just give up?
Is it going to be like getting into Dante's hell?" said Rasmussen of
Columbia University. "I am very concerned that people are holding on to
this hope that a vaccine will solve everything, and vaccines are not perfect,
just like any therapy. They fail."
All approved
vaccines must prove to be safe and effective, but that does not mean that
performance is the same. The measles vaccine is one of the best – 98% effective
in preventing the disease. But the flu vaccine is 40% to 60% effective in most
years. And some vaccines work worse in some groups of people – in the elderly,
for example, who have less robust immune responses and need a special vaccine
in high doses against influenza, or one with an extra ingredient called
adjuvant.
U.S. regulators
will require a coronavirus vaccine to be 50% effective, and if it can simply
exceed that threshold, public awareness will be needed to help communicate the
number of people who need to receive it to establish group immunity – the
threshold from which there is enough immune population to stop the spread when
the virus is actually controlled.
"If a
vaccine is limited to complying with the guidelines, the probability is that
group immunity cannot be achieved," says Walter Orenstein, associate
director of the Emory Vaccine Center. "Reduces transmission substantially.
Decreases the risk of exposure, but does not eliminate it. But a 50% effective
vaccine is much better than a 0% effective vaccine. I would take it."
Even the word
"effective" will be examined by experts and may need to be carefully
explained. The goal is a vaccine that prevents infections at all. But that's
not the only definition of a successful vaccine, which may include shots that
reduce the severity of symptoms people experience. Ideally, a vaccine would do
both. But what happens in real life will influence decisions about who will
take the vaccine first.
"We talk
about doing something that works, and public health is very much about
citizens," said Natalie Dean, biostatistics at the University of Florida.
"Something can be done that works perfectly in the laboratory; it's
completely different to make it work in the community."
A vaccine that
primarily decreases the severity of the disease can be targeted at older people
and others at higher risk of suffering worse consequences. A vaccine that
prevents infections well but does not work so well in older people can be
directed at the younger population to try to protect the elderly.
The effectiveness
of a vaccine also influences the amount of people who need to take it to
achieve group immunity.
Paul Offit,
director of the Vaccine Education Center at Philadelphia Children's Hospital,
quickly outlined a scenario with an optimistic result: let's say a vaccine is
75% effective at preventing people from spreading the virus and transmitting
it. Vaccinating, even if only a few people, will slow the spread, with the best
results to emerge if the first doses are channeled to the right people.
However, he estimated that it would be necessary to vaccinate two-thirds of the
population to achieve group immunity.
"If we're
talking about hugging, sitting with 67,000 people at the Philadelphia Eagles
game, I imagine it might take a few years," Offit said.
"A launch,
not a bomb"
The coronavirus
quickly fell on us, altering everyday life in unimaginable ways practically
overnight. Schools are closed. The Earth has stopped vibrating so much.
Impatient for the pandemic to relieve the world of its heavy burden, all eyes
turned to the vaccine.
"I think
everyone is so sick of this pandemic and this damn virus that they really look
at the vaccine like a savior," says Mark Mulligan, director of The Langone
Vaccine Center at New York University.
Mulligan believes
that people should look at vaccines in large part the same way they viewed
deconfinement – as something that must happen gradually in order for it to be
safe, and can even reverse as you learn more. Governments and businesses are
investing billions of dollars to increase the supply of the vaccine now, but
even so, it will not be possible to vaccinate everyone in the first week or
even in the first month after the first vaccine becomes available. The world
will become safer, little by little, not at once.
"The vaccine
will be a launch, not a bomb," said Andrew Noymer, an epidemiologist at
the University of California at Irvine.
And the flaws
that have disrupted the ability to test – including the challenges posed to
distribution and ensuring that the supply chain of basic components is robust –
are a major risk.
Public
communication will have to be differentiated, with leaders giving responsible
examples. President Donald Trump, able to take advantage of daily tests with
fast response times, has only recently set an example for the precautions that
public health experts said the rest of the country should take, helping to sow
confusion with masks. Throughout the pandemic, sports stars and celebrities
seemed to have had easier access to the tests than the rest of the people. If
such inequalities happen with vaccines, it can give people false confidence
about what is safe.
"What
happens when politicians have priority [for a vaccine]... is that there is a
projection of invincibility and those who are not vaccinated let their guard
down," said Saad Omer, director of the Institute for Global Health at Yale
University. "This happened in relation to the tests and the masks. It's
not an invention, and we're not ready for it."
"There's a
very short-eyed focus on this small part of the outbreak response, development
and research," said Dean of the University of Florida. "So we neglect
what is less exciting, but probably with more impact on the immediate and that in
the long run will be really important, also as to our confidence that we will
be safe."
Carolyn Johnson
is a science journalist. Previously investigated the health business and
accessibility of health services to users.
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