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China’s reopening has been marked by a conspicuous dearth of new Covid variants. The
country went almost overnight from the strictest control measures to
the most lax at the end of last year, after China abruptly dropped its
zero tolerance approach and allowed the virus to rip. The pathogen
followed.
The country’s chief epidemiologist estimated 80% of the population, more than 1.1 billion people, were infected in just a few weeks. Millions
then returned to their hometowns for the Lunar New Year holiday,
sparking fear that new variants from the massive outbreak could spread
to every corner of the country. The US and many European countries
required negative Covid tests for travelers from China to keep out
theoretical new mutations. But none have materialized. Health
officials from 28 regions across China — including every major city —
have been sending genetic information on recent infections to GISAID,
a consortium tracking the pandemic. None deviate from the variants that
were circulating widely in the rest of the world in the second half of
2022. All are various flavors of omicron, the most common variant of
concern. The same
is true for the rest of the world, where there hasn’t been a significant
new variant to challenge omicron in more than a year. That doesn’t mean
there won’t be future surges of infection. Officials remain concerned
that mutations within the omicron family may eventually cause havoc, by
evading existing immunity or triggering more severe disease. The World Health Organization is tracking four omicron lineages
closely because of the potential risk, including signals they may be
more fit or transmit more easily. The biggest targets at the moment are
recombinant variants, when two earlier strains come together. The most common is XBB.1.5, which an evolutionary professor dubbed Kraken on Twitter. The WHO has issued two rapid risk assessments of
it in recent weeks, concluding that it’s likely to spur an increase in
cases globally in the coming weeks. Fortunately, there’s no evidence
that it’s more dangerous than older versions of the virus. It’s not coming from China, however. The US is the epicenter for XBB.1.5, where it accounted for nearly 75% of all infections last week. China
will continue to monitor for new variants, said George Gao, a professor
at the Institute for Microbiology at the Chinese Academy of Sciences
and the former head of the Chinese Center for Disease Control and
Prevention. He led a study,
published in The Lancet, that found most Covid cases circulating in
Beijing — and likely all of China — are the older BA5.2 and BF.7
variants. That
doesn’t mean China is out of the woods. While the findings are
reassuring, it’s possible that humans in other parts of the country
could transmit the virus to animals, two experts from South Africa wrote
in a commentary that accompanied the article. That’s a particularly
dangerous event if it “spills back” into people in a further evolved
version, they said. Of course, that could happen anywhere. —Michelle Fay Cortez |