many people around the world are asking
themselves how many doses of the coven
19 vaccine they'll need and how often
protection from vaccines starts winning
after a few months so the us and other
countries are expediting booster shots
to fight rising infections we have
booster shots for the whole nation
people in a handful of places including
chile and israel have even started
getting boosters of boosters i'm getting
the fourth shot today because i think
it's important for
protection here in tel aviv researchers
have been conducting clinical trials for
these four shots the good news is
preliminary results from the pfizer
trials show a five-fold increase in
antibodies researchers hear say that
could mean increased protection we did
not see any severe significant adverse
events but scientists are still trying
to determine just how effective these
fourth doses are and how long that
protection can last and some warn
against rushing to add more boosters
regarding a first fourth dose i'm not
convinced at all i think that's why it
should be done in a clinical trial so we
looked at what the scientists know and
why many epidemiologists say repeated
doses shouldn't be given out so quickly
scientists say vaccine effectiveness
starts to decrease at around 6 months
and that's where boosters come in
in simple terms this is how it works we
all have these y-shaped molecules called
antibodies they are produced naturally
by our body's immune system to help stop
a virus from intruding when a virus
enters our system our body responds in a
number of ways the first defense is by
creating unique antibodies that bind to
it in order to neutralize it or remove
it the covin-19 vaccine helps the body
to make these antibodies and evolve any
existing ones and to keep the virus out
but after a while numbers can dwindle
and that protection fades
booster doses increase the number of
antibodies again and continue to advance
the body's understanding of the virus
now researchers in israel where code
vaccinations started earlier than in
other countries say the protection from
those boosters is waning too in as
little as three months in some cases
professor gilireg of yochai and her team
are working to determine how effective a
fourth dose will be in renewing immunity
loss after the third shot people here
that came to this study are only four
months after uh the third dose the doses
are being tested on staff members who
received a third pfizer shot in august
shurik gulper is a physician at the
hospital i didn't have any
large concerns
participating in the trial i think i
would take vaccine every six months if
that's what medically is recommended
the trial has around 300 participants in
total half are receiving another pfizer
shot while the rest are getting moderna
the logic behind this is that we think
that there may be a benefit of combining
vaccines we're hopeful that we will see
something additive when we give
or boost the immune response with
something slightly different the shots
participants got were the same as are
used in normal vaccination cycles
pfizer moderna and johnson johnson which
produces a single dose vaccine all say
they were developing omicron specific
vaccines but those updates could take
months to be produced
for now drug makers are approaching
additional doses differently pfizer ceo
albert burles said a fourth dose is not
necessarily needed while moderna advised
that those who have had three doses of
its vaccine may need a second booster by
fall
for these researchers it will also take
time to draw conclusions that can answer
questions such as how long protection
from extra boosters can last
but like many other experts around the
world regulate already says four shots
should be given out to everyone i would
think that probably
we need to save these vaccines only to
really the people who are very
vulnerable and needed and not give it
out to the whole population
in other words people who are
immunocompromised for example are more
exposed to the risk of getting seriously
ill even after vaccination but for
healthy individuals some scientists
argue two or three shots already offer
enough protection for the worst symptoms
that argument comes as research suggests
the omicron variant may cause milder
infection hospitalizations associated
with omicron in the u.s are lower
compared to prior variants though it
could be too soon to make definitive
conclusions
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the number of daily chronovirus cases
reached new highs this winter and
countries with high rates of vaccination
are taking different approaches to
second boosters some are racing ahead
israelis offer them to at risk groups
while chile and brazil are also moving
to provide additional doses after
initial campaigns use less effective
chinese-made vaccines
but government experts in the uk said a
second booster shot isn't a priority and
eu regulators said frequent shots could
weaken the immune system it's not
something that we can think
should be repeated constantly while the
world health organization questioned
blanket booster programs could in fact
prolong the pandemic by diverting supply
to countries that already have high
levels of vaccination coverage
giving the virus more opportunity to
spread and mutate
for now in tel aviv researchers also
recommend taking more time for
reflection
i hope that it's not going to be a
policy of giving it to everybody at
least not yet when we don't have data if
we will learn that that's really what's
necessary it might change the story but
i'm not convinced about that
you