NEW YORK, USA
Two years into the COVID-19
pandemic, most of the world has seen a dramatic improvement in infections,
hospitalizations and death rates in recent weeks, signaling the crisis appears
to be winding down. But how will it end? Past epidemics may provide clues.FILE - Dr. Joseph Ballinger giving Marjorie Hill, a nurse at Montefiore Hospital in New York, the first Asian flu vaccine shot to be administered in New York on Aug. 16, 1957
The ends of epidemics are not
as thoroughly researched as their beginnings. But there are recurring themes
that could offer lessons for the months ahead, said Erica Charters of the
University of Oxford, who studies the issue.
“One thing we have learned is
it’s a long, drawn-out process” that includes different types of endings that
may not all occur at the same time, she said. That includes a “medical end,”
when disease recedes, the “political end,” when government prevention measures
cease, and the “social end,” when people move on.
The COVID-19 global pandemic
has waxed and waned differently in different parts of the world. But in the
United States, at least, there is reason to believe the end is near.
About 65% of Americans are
fully vaccinated, and about 29% are both vaccinated and boosted. Cases have
been falling for nearly two months, with the U.S. daily average dropping about
40% in the last week alone. Hospitalizations also have plummeted, down nearly
30%. Mask mandates are vanishing — even federal health officials have stopped
wearing them — and President Joe Biden has said it’s time for people to return
to offices and many aspects of pre-pandemic life.
But this pandemic has been
full of surprises, lasting more than two years and causing nearly 1 million
deaths in the U.S. and more than 6 million around the world. Its severity has
been surprising, in part because many people drew the wrong lesson from a
2009-2010 flu pandemic that turned out to be nowhere as deadly as initially
feared.
“We got all worried but then
nothing happened (in 2009), and I think that was what the expectation was” when
COVID-19 first emerged, said Kristin Heitman, a Maryland-based researcher who
collaborated with Charters.
That said, some experts
offered takeaways from past epidemics that may inform how the end of the
COVID-19 pandemic may play out.
FLU
Before COVID-19, influenza was
considered the most deadly pandemic agent. A 1918-1919 flu pandemic killed 50
million people around the world, including 675,000 in the U.S., historians
estimate. Another flu pandemic in 1957-1958 killed an estimated 116,000
Americans, and another in 1968 killed 100,000 more.
A new flu in 2009 caused
another pandemic, but one that turned out not to be particularly dangerous to
the elderly — the group that tends to die the most from flu and its
complications. Ultimately, fewer than 13,000 U.S. deaths were attributed to
that pandemic.
The World Health Organization
in August 2010 declared the flu had moved into a post-pandemic period, with
cases and outbreaks moving into customary seasonal patterns.
In each case, the pandemics
waned as time passed and the general population built immunity. They became the
seasonal flu of subsequent years. That kind of pattern is probably what will
happen with the coronavirus, too, experts say.
“It becomes normal,” said
Matthew Ferrari, director of Penn State’s Center for Infectious Disease
Dynamics. “There’s a regular, undulating pattern when there’s a time of year
when there’s more cases, a time of year when there’s less cases. Something that’s
going to look a lot like seasonal flu or the common cold.”
HIV
In 1981, U.S. health officials
reported a cluster of cases of cancerous lesions and pneumonia in previously
healthy gay men in California and New York. More and more cases began to
appear, and by the next year officials were calling the disease AIDS, for
acquired immune deficiency syndrome.
Researchers later determined
it was caused by HIV — human immunodeficiency virus — which weakens a person’s
immune system by destroying cells that fight disease and infection. For years,
AIDS was considered a terrifying death sentence, and in 1994 it became the
leading cause of death for Americans ages 25 to 44.
But treatments that became
available in the 1990s turned it into a manageable chronic condition for most
Americans. Attention shifted to Africa and other parts of the world, where it
was not controlled and is still considered an ongoing emergency.
Pandemics don’t end with a
disease ebbing uniformly across the globe, Charters said. “How a pandemic end
is generally by becoming multiple (regional) epidemics,” she said.
ZIKA
In 2015, Brazil suffered an outbreak
of infections from Zika virus, spread by mosquitoes that tended to cause only
mild illness in most adults and children. But it became a terror as it emerged
that infection during pregnancy could cause a birth defect that affected brain
development, causing babies to be born with unusually small heads.
By late that year, mosquitoes
were spreading it in other Latin American countries, too. In 2016, the WHO
declared it an international public health emergency, and a U.S. impact became
clear. The Centers for Disease Control and Prevention received reports of 224
cases of Zika transmission by mosquitoes in the continental United States and
more than 36,000 in U.S. territories — the vast majority in Puerto Rico.
But the counts fell
dramatically in 2017 and virtually disappeared shortly after, at least in the
U.S. Experts believe the epidemic died as people developed immunity. “It just
sort of burned out” and the pressure for making a Zika vaccine available in the
U.S. ebbed, said Dr. Denise Jamieson, a former CDC official who was a key
leader in the agency’s responses to Zika.
It’s possible Zika will be a
dormant problem for years but outbreaks could occur again if the virus mutates
or if larger numbers of young people come along without immunity. With most
epidemics, “there’s never a hard end,” said Jamieson, who is now chair of
gynecology and obstetrics at Emory University’s medical school.
COVID-19
The Geneva-based WHO declared
COVID-19 a pandemic on March 11, 2020, and it will decide when enough countries
have seen a sufficient decline in cases — or, at least, in hospitalizations and
deaths — to say the international health emergency is over.
The WHO has not yet announced
target thresholds. But officials this week responded to questions about the
possible end of the pandemic by noting how much more needs to be accomplished
before the world can turn the page.
COVID-19 cases are waning in
the U.S., and dropped globally in the last week by 5%. But cases are rising in
some places, including the United Kingdom, New Zealand and Hong Kong.
People in many countries need
vaccines and medications, said Dr. Carissa Etienne, director of the Pan
American Health Organization, which is part of the WHO.
In Latin America and the
Caribbean alone, more than 248 million people have not yet had their first dose
of COVID-19 vaccine, Etienne said during a press briefing with reporters.
Countries with low vaccination rates likely will see future increases in
illnesses, hospitalizations and deaths, she said.
“We are not yet out of this
pandemic,” said Dr. Ciro Ugarte, PAHO’s director of health emergencies. “We
still need to approach this pandemic with a lot of caution.”
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