Science - USA (2022-01-07)

10 7 JANUARY 2022 • VOL 375 ISSUE 6576 science.org SCIENCE

COVID-19 case numbers. But other changes
may play a role as well.
One is the variant’s ability to get around
immunity provided by previous infections
and vaccines. A study of SARS-CoV-2 spread
in nearly 12,000 households in Denmark,
posted on 27 December 2021, provides some
of the clearest evidence of Omicron’s advan-
tage. Economist Frederik Plesner Lyngse
of the University of Copenhagen and the
Danish Statens Serum Institute and his
colleagues found that in households with
a Delta outbreak, the unvaccinated were
twice as likely to be infected by a household
member as those who were fully vaccinated.
In households struck by Omicron, un-
vaccinated and fully vaccinated people had
roughly equal chances of catching the virus.
That doesn’t mean COVID-19 shots don’t
work; other data clearly show they still
prevent severe disease. And in the Danish
study, a booster shot cut the risk of infec-
tion by Omicron in half. Being vaccinated
also reduces an infected person’s chance
of infecting others, Lyngse notes: For both
variants, an unvaccinated case was 41%
more likely to infect another household
member than a fully vaccinated one.
There’s another possible explanation for
Omicron’s explosive spread that the house-
hold study would not be able to pick up,
notes epidemiologist Bill Hanage of the
Harvard T.H. Chan School of Public Health.
If the virus is really better at replicating
in the upper airways, it might be expelled
more readily into the surrounding air, mak-
ing it more likely to trigger superspreading
events. And if it truly causes milder illness,
even people who shed a lot of virus might
have few symptoms, making them more
likely to be out and about. If so, banning
large gatherings and closing down nightlife
and restaurants might be even more effec-
tive at slowing the spread of Omicron than
that of previous variants, Hanage says.

Is Omicron sending fewer people to the
hospital than previous variants?
Data from South Africa, where cases have
already started to decline, suggest Omi-
cron put one-third as many people in the
hospital as the Delta variant did. But previ-
ous infections and the country’s relatively
young population may have helped keep
severe cases low.
Initial hospital data from England and
Denmark also suggest Omicron cases are
less severe. But those countries have high
vaccination rates, and there, too, Omicron
has spread most quickly among younger
adults. Severe cases may increase in the
wake of holiday parties where people
of all ages mixed. “If we see that Omi-
cron is capable of causing severe disease

in older age groups ... I think it could be

much worse than most people are thinking

about at the moment,” Hanage says. The

U.S. picture looks less hopeful: More than

100,000 people there were hospitalized

with COVID-19 when Science went to

press—up from 75,000 a week earlier.

Moreover, there are signs Omicron can

trigger dehydration from fever, vomiting,

and diarrhea and can exacerbate other

health issues such as diabetes. Such cases

need less intensive care, but can still over-

whelm hospitals. “I’m hearing story af-

ter story after story of hospitals that are

full, health care workers that are infected,

that can’t do their job,” says Maria van

Kerkhove, an epidemiologist at the World

Health Organization (WHO).

How severe Omicron is in people who

are “immunologically naïve”—neither vac-

cinated nor previously infected—remains

an open question. They are now a minor-

ity in most countries, but they too could

add to the hospital burden if they get seri-

ously ill. Deaths in Ghana, Ivory Coast, and

Madagascar, where vaccination rates are

low, are increasing sharply as COVID-

cases surge.

Is Omicron the last variant of concern?

Probably not. More variants with Omicron’s

ability to evade immunity and spread suc-

cessfully are likely to emerge, says Aris

Katzourakis, who studies virus evolution

at the University of Oxford—and they

may prove more virulent than Omicron.

After all, even Omicron itself may not

have evolved to cause less severe disease,

Katzourakis notes. It may be milder than

Alpha or Delta, but it branched off from the

family tree before those variants emerged.

“Is it milder than what it evolved from? I

don’t think we know the answer to that,”

Katzourakis says.

The next variant to make global head-

lines may already be circulating. WHO is

tracking two “variants of interest” and three

“variants under monitoring,” as well as

30 sublineages of Delta, Van Kerkhove

says. “There are many more Greek letters

that we can potentially go through.”

But Omicron itself may help tame what-

ever comes next. Vaccination and natural

infections have exposed many millions of

people to earlier versions of SARS-CoV’s

spike protein, training their immune sys-

tem to respond to those variants. Infec-

tions with Omicron, whose spike looks

different, will likely both strengthen and

broaden immunity, Hanage says, hopefully

making new variants less dangerous. “I

suspect that immunity, post-Omicron, will

be pretty broad,” Hanage says. “But I don’t

want to bet on it.” j

L

ast month, the U.S. government won

the first conviction of an academic

scientist under its 3-year-old China

Initiative, when a federal jury in Bos-

ton found Harvard University chemist

Charles Lieber guilty of lying about his

research ties to China.

Andrew Lelling, the former U.S. attorney

who led the investigation that 2 years ago

resulted in criminal charges against Lieber,

thinks it could also be the last such convic-

tion. One reason is that defense attorneys

now might choose to seek a plea bargain

for their clients rather than risk an adverse

verdict. And Lelling thinks the government

could become more selective in deciding

which cases to prosecute, focusing on immi-

nent threats to U.S. economic and national

security rather than violations of rules that

require federally funded researchers to dis-

close all sources of research support.

Critics of the initiative have long argued

for a narrower focus. They say it too often

criminalizes bookkeeping mistakes by oth-

erwise blameless researchers. They also

believe prosecutions like Lieber’s unneces-

sarily harm U.S. innovation by scaring sci-

entists away from engaging in important

research collaborations.

“Yes, [the initiative has] been a deterrent,

just like cutting off the hands of thieves,”

says Peter Zeidenberg, a lawyer with Ar-

ent Fox who has defended several scientists

charged under the China Initiative. “But it’s

also been terrifying. And it is not justice,

nor is it of value to society.”

So far, the government has prosecuted

some two dozen academic scientists it says

abetted China’s efforts to steal U.S.-funded

technology by not disclosing their ties to

research programs funded by the Chinese

government. Its record has been mixed. In

eight cases, academics have pleaded guilty

What the

Lieber verdict

means for the

China Initiative

Jury finds Harvard

University chemist guilty of

lying about ties to China

SCIENCE AND SECURITY

By Jeffrey Mervis

NEWS | IN DEPTH