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 Vaccine protection remains very strong against severe infections and
hospitalizations caused by any version of the coronavirus, and those
most at risk are still the unvaccinated, according to interviews
with 10 leading COVID-19 experts.
The major worry about the Delta variant, first identified in India,
is not that it makes people sicker, but that it spreads far more
easily from person to person, increasing infections and
hospitalizations among the unvaccinated.
Evidence is also mounting that it is capable of infecting fully
vaccinated people at a greater rate than previous versions, and
concerns have been raised that they may even spread the virus, these
experts said.
"The biggest risk to the world at the moment is simply Delta," said
microbiologist Sharon Peacock, who runs Britain's efforts to
sequence the genomes of coronavirus variants, calling it the
"fittest and fastest variant yet."
Viruses constantly evolve through mutation, with new variants
arising. Sometimes these are more dangerous than the original.
Until there is more data on Delta variant transmission, disease
experts say that masks, social distancing and other measures set
aside in countries with broad vaccination campaigns may again be
needed.
Public Health England said on Friday that out of a total of 3,692
people hospitalized in Britain with the Delta variant, 58.3% were
unvaccinated and 22.8% were fully vaccinated.
In Singapore, where Delta is the most common variant, government
officials reported on Friday https://www.reuters.com/world/asia-pacific/vaccinated-people-singapore-make-up-three-quarters-recent-covid-19-cases-2021-07-23
that three quarters of its coronavirus cases occurred among
vaccinated individuals, though none were severely ill.
Israeli health officials have said 60% of current hospitalized COVID
cases are in vaccinated people. Most of them are age 60 or older and
often have underlying health problems.
In the United States, which has experienced more COVID-19 cases and
deaths than any other country, the Delta variant represents about
83% of new infections. So far, unvaccinated people represent nearly
97% of severe cases.
"There is always the illusion that there is a magic bullet that will
solve all our problems. The coronavirus is teaching us a lesson,"
said Nadav Davidovitch, director of Ben Gurion University's school
of public health in Israel.
'TEACHING US A LESSON'
The Pfizer Inc/BioNTech vaccine, one of the most effective against
COVID-19 so far, appeared only 41% effective at halting symptomatic
infections in Israel over the past month as the Delta variant
spread, according to Israeli government data. Israeli experts said
this information requires more analysis before conclusions can be
drawn.
"Protection for the individual is very strong; protection for
infecting others is significantly lower," Davidovitch said.
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 A study in China found that
people infected with the Delta variant carry
1,000 times more virus in their noses compared
with the ancestral Wuhan strain first identified
in that Chinese city in 2019.
"You may actually excrete more virus and that's why it's more
transmissible. That's still being investigated," Peacock said.
Virologist Shane Crotty of the La Jolla Institute for Immunology in
San Diego noted that Delta is 50% more infectious than the Alpha
variant first detected in the UK.
"It's outcompeting all other viruses because it just spreads so much
more efficiently," Crotty added. Genomics expert
Eric Topol, director of the Scripps Research Translational Institute
in La Jolla, California, noted that Delta infections have a shorter
incubation period and a far higher amount of viral particles.
"That's why the vaccines are going to be challenged. The people who
are vaccinated have got to be especially careful. This is a tough
one," Topol said.
In the United States, the Delta variant has arrived as many
Americans - vaccinated and not - have stopped wearing masks indoors.
"It's a double whammy," Topol said. "The last thing you want is to
loosen restrictions when you're confronting the most formidable
version of the virus yet."
The development of highly effective vaccines may have led many
people to believe that once vaccinated, COVID-19 posed little threat
to them.
"When the vaccines were first developed, nobody was thinking that
they were going to prevent infection," said Carlos del Rio, a
professor of medicine and infectious disease epidemiology at Emory
University in Atlanta. The aim was always to prevent severe disease
and death, del Rio added. The vaccines were so
effective, however, that there were signs the vaccines also
prevented transmission against prior coronavirus variants.
"We got spoiled," del Rio said.
Dr. Monica Gandhi, an infectious diseases doctor at the University
of California, San Francisco, said, "People are so disappointed
right now that they're not 100% protected from mild breakthroughs" -
getting infected despite having been vaccinated.
But, Gandhi added, the fact that nearly all Americans hospitalized
with COVID-19 right now are unvaccinated "is pretty astounding
effectiveness."
(Reporting by Julie Steenhuysen in Chicago, Alistair Smout in
London, Ari Rabinovitch and Maayan Lubell in Jerusalem; Editing by
Will Dunham)
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