[Future COVID-19 booster shots will likely need fresh formulations
as new coronavirus variants of concern continue to emerge. ]
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COVID FUTURE: HOW MANY BOOSTERS WILL WE NEED?  
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David R. Martinez
June 2, 2022
The Conversation
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_ Future COVID-19 booster shots will likely need fresh formulations
as new coronavirus variants of concern continue to emerge. _

Viral surveillance and prediction may be key parts of figuring out
what goes into a vaccine,

 

Being up to date on COVID-19 vaccines means having had three or four
doses
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of the same shot at this point. Current boosters are the same
formulations as the first authorized shots, based on the original
strain of the coronavirus
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late 2019. They do still protect
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against severe COVID-19, hospitalizations and deaths. But as immunity
wanes over time and new, more contagious SARS-CoV-2 variants emerge,
the world needs a long-term boosting strategy.

I’m an immunologist
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who studies immunity to viruses. I was a part of the teams that helped
develop the Moderna
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and Johnson & Johnson SARS-CoV-2 vaccines
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and the monoclonal antibody therapies
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from Eli Lilly and AstraZeneca.

[out of focus smiling woman extends her arm holding vaccination record
card]
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How many lines will ultimately be filled out on your COVID-19
vaccination card? LPETTET/E+ via Getty Images
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I often get asked how frequently, or infrequently, I think people are
likely to need COVID-19 booster shots in the future. No one has a
crystal ball to see which SARS-CoV-2 variant will come next or how
good future variants will be at evading vaccine immunity. But looking
to other respiratory viral foes that have troubled humanity for a
while can suggest what the future could look like.

Influenza virus provides one example. It’s endemic in humans,
meaning it hasn’t disappeared and continues to cause recurrent
seasonal waves of infection in the population. Every year officials
try to predict the best formulation of a flu shot to reduce the risk
of severe disease.

As SARS-CoV-2 continues to evolve and is likely to become endemic
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it is possible people may need periodic booster shots for the
foreseeable future. I suspect scientists will eventually need to
update the COVID-19 vaccine to take on newer variants, as they do for
flu.

Forecasting flu, based on careful surveillance

Influenza virus surveillance offers a potential model for how
SARS-CoV-2 could be tracked over time. Flu viruses have caused several
pandemics, including the one in 1918 that killed an estimated 50
million people worldwide
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Every year there are seasonal outbreaks of flu, and every year
officials encourage the public to get their flu shots
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Each year, health agencies including the World Health Organization’s
Global Influenza Surveillance and Response System
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make an educated guess based on the flu strains circulating in the
Southern Hemisphere about which ones are most likely to circulate in
the Northern Hemisphere’s upcoming flu season. Then large-scale
vaccine production begins, based on the selected flu strains.

Some flu seasons, the vaccine doesn’t turn out to be a great match
with the virus strains
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that end up circulating most widely. Those years, the shot is not as
good at preventing severe illness. While this prediction process is
far from perfect, the flu vaccine field has benefited from strong
viral surveillance systems and a concerted international effort by
public health agencies to prepare.

While the particulars for influenza and SARS-CoV-2 viruses are
different, I think the COVID-19 field should think about adopting
similar surveillance systems in the long term. Staying on top of what
strains are circulating will help researchers update the SARS-CoV-2
vaccine to match up-to-date coronavirus variants.

How SARS-CoV-2 has evolved so far

SARS-CoV-2 faces an evolutionary quandary as it reproduces and spreads
from person to person. The virus needs to maintain its ability to get
into human cells using its spike protein, while still changing in ways
that allow it to evade vaccine immunity. Vaccines are designed to get
your body to recognize a particular spike protein, so the more it
changes, the higher the chance that the vaccine will be ineffective
against the new variant.

Despite these challenges, SARS-CoV-2 and its variants have
successfully evolved to be more transmissible and to better evade
people’s immune responses. Over the course of the COVID-19 pandemic,
a new SARS-CoV-2 variant of concern has emerged and dominated
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transmission in a series of contagion waves every four to seven
months. Almost like clockwork, the D614G variant emerged in the spring
of 2020 and overtook the original SARS-CoV-2 outbreak strain. In late
2020 and early 2021, the alpha variant emerged and dominated
transmission. In mid-2021, the delta variant overtook alpha and then
dominated transmission until it was displaced by the omicron variant
at the end of 2021.

There’s no reason to think this trend won’t continue. In the
coming months, the world may see a dominant descendant of the various
omicron subvariants
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And it’s certainly possible a new variant will emerge from a
nondominant pool of SARS-CoV-2, which is how omicron itself came to
be.

Current booster shots are simply additional doses of the vaccines
based on the outbreak SARS-CoV-2 virus strain that has long been
extinct. The coronavirus variants have changed a lot from the original
virus, which doesn’t bode well for continued vaccine efficacy. The
idea of tailor-made annual shots – like the flu vaccine – sounds
appealing. The problem is that scientists haven’t yet been able to
predict what the next SARS-CoV-2 variant will be with any degree of
confidence.

[people walk near a tent marked 'Vaccines | Boosters']
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Periodic booster shots may be in order for the foreseeable future.
Spencer Platt/Getty Images
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Planning for the future

Yes, the dominant SARS-CoV-2 variants in the upcoming fall and winter
seasons may look different from the omicron subvariants currently
circulating. But an updated booster that more closely resembles
today’s omicron subvariants, coupled with the immunity people
already have from the first vaccines, will likely offer better
protection going forward. It might require less frequent boosting –
at least as long as omicron sublineages continue to dominate.

The Food and Drug Administration is set to meet in the coming weeks to
decide what the fall boosters should be in time for manufacturers to
produce the shots. Vaccine makers like Moderna are currently testing
their booster candidates in people and evaluating the immune response
against newly emerging variants
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The test results will likely decide what will be used in anticipation
of a fall or winter surge.

Another possibility is to pivot the vaccine booster strategy to
include universal coronavirus vaccine approaches that already look
promising in animal studies. Researchers are working toward what’s
called a universal vaccine which would be effective against multiple
strains. Some focus on chimeric spikes
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spike of different coronaviruses together in one vaccine, to broaden
protective immunity. Others are experimenting with
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vaccines [[link removed]] that get the
immune system to focus on the most vulnerable regions within the
coronavirus spike.

These strategies have been shown to ward off difficult-to-stop
SARS-CoV-2 variants in lab experiments. They also work in animals
against the original SARS virus that caused an outbreak in the early
2000s as well as zoonotic coronaviruses from bats that could jump into
humans, causing a future SARS-CoV-3 outbreak.

Science has provided multiple safe and effective vaccines that reduce
the risk of severe COVID-19. Reformulating booster strategies, either
toward universal-based vaccines or updated boosters, can help steer us
out of the COVID-19 pandemic.[The Conversation]

David R. Martinez
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Postdoctoral Fellow in Epidemiology, _University of North Carolina at
Chapel Hill
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This article is republished from The Conversation
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the original article
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* COVID-19
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* vaccines
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* Science
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* Evolution
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* viruses
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