16 | New Scientist | 19 March 2022LIKE some other countries,
Iceland has scrapped its remaining
covid-19 restrictions. Unlike other
nations, however, its health
ministry coupled this move with
a startling announcement: the
country will start aiming for
herd immunity.
“Widespread societal resistance
to covid-19 is the main route out
of the epidemic,” the government
said in a statement on 23 February.
“To achieve this, as many people
as possible need to be infected
with the virus as the vaccines are
not enough, even though they
provide good protection against
serious illness.”
Until now, Iceland has adopted
a “zero covid” strategy, which has
contributed to it having one ofthe world’s lowest covid-19 death
rates. The country has recorded
just 79 covid-19 deaths since
the start of the pandemic in
a population of 366,000.
On 25 February, Iceland lifted
all its remaining restrictions,
allowing an unlimited number
of people to gather indoors and
fully opening its border. Since
then, official government
statistics show that daily case
numbers of covid-19 have fallen
from 4862 to 2656 on 11 March.
The phrase herd immunity is
controversial in itself. It has no set
definition, but is often associated
with allowing the SARS-CoV-
coronavirus to spread while
vulnerable people shield. When
the virus has infected most of
the population, the hope is thatoutbreaks would fizzle out.
Almost all experts agree this
definition of herd immunity
cannot be achieved. In January
2021, hospitals in the Brazilian
Amazon collapsed under the
strain of covid-19, despite the
region having had a high infection
rate in its first wave. Later that
year, it emerged that nearly
everyone in Iran had caught the
disease at least once, but herd
immunity wasn’t achieved.
Immunity wanes after a
person overcomes SARS-CoV-
or is vaccinated against it. The
virus has also mutated into new
variants, which somewhat evade
past immunity.
Nevertheless, a past infection
may reduce the risk of becoming
seriously ill with a different
variant. This is the population-
level immunity that Iceland
hopes to harness, says Gudrun
Aspelund at the country’s
Directorate of Health. Individuals
aren’t advised to deliberately
get infected and are encouraged
to test and isolate, she says.
The lifting of restrictions
was partially driven by growing
confidence in omicron’s reduced
severity compared with previous
variants, says Aspelund. In
addition, 80 per cent of thepopulation have had two vaccine
doses, helping to keep the number
of deaths low.
However, while younger people
are at reduced risk of coronavirus
complications, they can still
develop long covid, says Christina
Pagel at University College London.
“We just don’t know enough about
the long-term impact,” she says.
“You’re asking for trouble.”
But the government felt it
had little choice, says Aspelund.
As well as being milder, omicron
is more transmissible than
previous variants, so extrememeasures would be required to
stop its spread. “We are talking
about severe restrictions on
gatherings, on working from
home, limiting society for a long
time,” says Aspelund. Trying
to achieve zero covid-19 cases
is no longer possible, she says.
“Not here, for sure.”After omicron
The threat of another variant
emerging is a worry for public
health experts. “We don’t know
what comes after omicron,” says
Francois Balloux at University
College London.
If the next variant is more
virulent and people retain some
of their immunity, then previously
overcoming omicron would be an
advantage, says Balloux. Recent
studies suggest the best protection
comes from being fully vaccinated
and having had an infection,
dubbed hybrid immunity.
Yet no one knows if omicron
immunity will protect against
a future variant. “There’s no
guarantee it’s going to provide
similar protection in a few
months’ time to whatever the
next variant happens to be,” says
Neil Mabbott at the University
of Edinburgh, UK.
Ultimately, Iceland’s lifting
of restrictions is similar to that
in other European countries, says
Balloux. In early January, England
reported more than 147,000 daily
cases. After falling considerably,
cases started rising at the end
of February, corresponding with
restrictions ending on 24 February.
Aspelund is clear that
the government doesn’t want
to encourage infections. “We
are not telling people to go
and have a covid party, but
how we look at it here is that
it is inevitable that people are
going to get it,” she says. ❚“ We just don’t know enough
about the long-term
impact of infection.
You’re asking for trouble”
CoronavirusSIGGAELLA
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MAGESIceland targets herd immunity
The country’s new covid-19 strategy aims for “widespread societal resistance” to the virus,
but most experts think this cannot be achieved, reports Clare WilsonCustomers sit outside
a restaurant in Reykjavik
in July 2020News
Scientists at a
covid-19 sequencing
lab in ReykjavikHA
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