CREDITS: (PHOTO DING TING/XINHUA VIA GETTY IMAGES; (GRAPHIC K. FRANKLIN/SCIENCE; (DATA OUR WORLD IN DATA334 22 APRIL 2022 • VOL 376 ISSUE 6591 science.org SCIENCEcome an undebatable political decision,” adds
Xi Chen, a public health scientist at the Yale
School of Public Health.
But whether China can still get back to
zero, as it did after the world’s first COVID-
outbreak in Wuhan in 2020 and every re-
surgence elsewhere since, is uncertain given
Omicron’s transmissibility. On 18 April, the
daily number of reported cases in Shanghai
had dropped somewhat, to 20,416, from a
peak of 28,145 cases on 13 April. But the lock-
down has been extended indefinitely. Mean-
while, other cities have entered partial or
complete shutdowns as well.
As elsewhere, Shanghai’s Omicron epi-
demic appears to be mild. Roughly 90% of
cases are reportedly asymptomatic, and by
19 April, the city had only reported 10 deaths.
(In all of China, only 12 COVID-19–related
deaths have been reported this year.)
Whether the numbers tell an accurate
story is unclear. One reason for the large
number of asymptomatic cases is the re-
peated testing of Shanghai residents,
which catches infections that would
fly under the radar in other coun-
tries. But Huang suspects Shanghai
officials are also counting people
who only have coldlike symptoms
as asymptomatic cases, because they
can be sent to the makeshift isola-
tion centers instead of hospitals.
As to severe cases and deaths, lo-
cal media have raised questions
about unexplained deaths at several
Shanghai nursing homes. Still, Chen
believes the numbers are “largely re-
liable.” He says severity is low because
most infections so far seem to have
occurred in younger people and be-
cause the outbreak is still in its early
phase. Also, identifying infections
early allows for timely treatment
that can forestall serious illness. “If
infections spill over to sizable older
populations, the results will be very
different from what we are seeing
now,” and more similar to Hong Kong, Chen
says. That city recorded the world’s highest
death rate in mid-March, in part because
many older people had foregone the vaccine.
Mainland China has a similar problem.
Airfinity, a London-based health analytics
firm, reported that nearly 19% of Chinese
people over age 60 were unvaccinated as
of mid-March. Among those in their 80s,
just over 50% had received two shots by 18
March, and only 19% had received boosters,
Zeng Yixin, deputy director of the National
Health Commission, reported at a press brief-
ing. (Across all ages, the picture looks better,
with 88% of the population fully vaccinated
and about 51% having received boosters.)
If Omicron spreads throughout China,
the low vaccination rate among the elderly
could lead to 1 million deaths in 3 months,
Airfinity estimates. In contrast, Australia,
New Zealand, and Singapore exited zero
COVID after only 1.2%, 0.6%, and 0.4%, re-
spectively, of their over-60 population wereunvaccinated. They have seen relatively few
deaths as a result.
Why China did worse is puzzling. Some
say the country’s leadership painted itself
into a corner by touting the success of zero
COVID and not preparing the public for a
transition to living with the virus. Because of
safety concerns about COVID-19 vaccines, the
campaign initially focused on younger popu-
lations. Vaccine hesitancy continues even
today. “One question I frequently get asked
is: ‘My parents are 80 years old [or] have
hypertension-diabetes, is it safer for them to
vaccinate or not vaccinate?’” says Zhangkai
Cheng, a respiratory specialist at Guangzhou
Medical University.
“Hesitancy among older adults is somehow
rational in the context of a zero COVID strat-
egy,” says University of Hong Kong (HKU)
epidemiologist Ben Cowling. “If a vaccine
has minimal but nonzero risk, whereas the
risk of COVID infection might be expected
to be minimal, some may prefer to take their
chances with the virus.” Now that this calcu-
lation has changed, some communities are
sending vaccination teams door-to-door to
persuade senior citizens to get the shots, of-
fering gift cards as an incentive.
A study by an HKU group provided some
reassurance about the effectiveness of the in-
activated virus vaccines used in China, which
has not authorized the messenger RNA
(mRNA) shots used in many other countries.
The effectiveness of two doses of Sinovac’s
inactivated vaccine was notably lower than
that of two doses of an mRNA vaccine among
adults 60 and older, the team found, but three
doses of either vaccine offered very good pro-
tection against severe illness and death.
China’s plans for exiting its zero COVID
stance are still in development. In a
letter published in Nature Medicine
on 5 April, two Chinese epidemio-
logists listed several measures the
country needs to implement to make
the shift this year, including expand-
ing the use of online health consulta-
tions, training health care workers to
better treat mild COVID-19 cases, and
stockpiling antivirals.
But few are willing to wager when
the transition will occur. “There is
no indication that the central gov-
ernment has begun to prepare for
a coexistence strategy,” says Xi Lu,
a National University of Singapore
specialist in Chinese economic
policy. “I speculate that China will
continue to implement the wrong
policies for a long time; and with
each day of delay, the transition will
become more difficult.” jWith reporting by Bian Huihui.February
2020January
2021January
20220500010,15,20,25,30,Cases (7-day rolling average)Workers converted Shanghai’s National Exhibition and Convention Center into a COVID-19 hospital in early April.
To zero and back
China’s “zero COVID” strategy has been successful for 2 years,
but now cases of the highly transmissible Omicron variant are surging.