[We should be very concerned for the people of China. They have
gone from a “zero COVID” policy to a “let it rip” policy. It
is possible that a variant of concern will arise from their disaster.
But the U.S. already has a problem of its own. ]
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COVID IN CHINA, THE U.S., AND EVERYTHING IN-BETWEEN  
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Katelyn Jetelina
December 29, 2022
Your Local Epdemiologist
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_ We should be very concerned for the people of China. They have gone
from a “zero COVID” policy to a “let it rip” policy. It is
possible that a variant of concern will arise from their disaster. But
the U.S. already has a problem of its own. _

,

 

Well, I was very much enjoying my holiday but COVID continues to do
its COVID thing. It’s time for an update.

China: A humanitarian disaster

As expected
[[link removed]],
the COVID-19 situation in China is out of hand. In an interesting turn
of events, China went from a “zero COVID” policy to a “let it
rip” policy by dropping all mitigation measures without fully
vaccinating the highest of risk or strengthening their healthcare
system.

Egregiously, they stopped reporting cases, hospitalizations, and
deaths, too. This looks good for them on paper, but when we rely on
epidemiology 101 and anecdotal reports, which are plentiful, the
situation in China is beyond grim.

Officials estimate between 5,000-10,000 people are dying per _day_.
(At the U.S. peak, we lost 3,800
[[link removed]] people per day). Epidemiologists expect
death toll to rise in China in the coming months leading to 0.5-1
million cumulative deaths. A humanitarian disaster.

This outbreak could have implications worldwide, like the emergence of
a variant of concern. The best we can tell
[[link removed]],
BF.7 is spreading in China, which is an Omicron subvariant about 3
evolutionary steps behind what is spreading in most of the world. But,
a new variant of concern could appear. (This is
more _possible _than _probable _because transmission is high
everywhere).

Just like cases and deaths, though, China is not reporting genomic
data. In other words, we don’t know if and how the virus is changing
and what it may (or may not) mean to the international community.

U.S. responds domestically

_So, how should the United States respond?_ Well, it depends on our
goal: delay or decrease transmission from China? Identify variants of
concern? Pressure the Chinese government to uphold international
responsibilities?

Yesterday, the U.S. publicly signaled two goals:

_DELAY TRANSMISSION. _On a scale from “do nothing” to “ban all
travel”, the U.S. chose something in the middle. Travelers coming to
the U.S. from China will be required to have a negative PCR test
within 48 hours of departure. This starts on January 5, 2023. I assume
the goal is to buy time—delay a wave in the U.S. seeded by
travelers. And this may be a legitimate concern, as Milan reported 
[[link removed]]that
50% of passengers on flights from China tested positive. However, the
extent to which this delays transmission, and by how much, is up for
debate:

Figure: The post-arrival transmission for pre-arrival testing. Wells
et al., 2022. Int J Public Health. Source here
[[link removed]].

*
As Adam Kucharski pointed out
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“uncontrolled domestic transmission will grow exponentially while
importations grow linearly. In other words, we’re much more likely
to get an infection from a fellow resident than a traveler.”

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The policy doesn’t start until next week in order for airlines to
prepare, which likely won’t help if transmission is already out of
control in China.

*
To test pre-departure within 48 hours of travel is
problematic. Studies 
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shown that this will reduce transmission by only 10%.

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*
Finally, buying time is only useful if we actually _did _something
to prepare.

Using back of the napkin math
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this policy would prevent ~10,000 infections in the U.S. If a variant
of concern did pop up and was 100% immune invasive and every passenger
had it (unlikely scenario), we would delay a wave by one week.

In any health crisis, policy decisions are challenging. Risks (ethics,
lack of effectiveness, potential other harms, like xenophobia) must be
weighed with benefits (low cost, possibility of delay). Then politics
get involved. Epidemiologically this policy isn’t adding up for me.

_FIND VARIANTS OF CONCERN. _The second goal is to find potential
variants of concern. Given zero data is being released by China,
enhanced surveillance of PCR cases with a travel history to China is
worthwhile. The U.S. will not have access to pre-departure testing
results in China, but we can do it once people arrive.

The CDC already has a great program in place
[[link removed]] (see
figure below), but because of the China situation, it expanded to 2
more airports. While this program is proactive, it’s not that big:
10% of passengers at 7 airports. We should expand our capacity even
more. It would be more advantageous to sequence airplane wastewater.

[Traveler-based SARS-CoV-2 Genomic Surveillance Overview diagram]
[[link removed]]

(CDC)

A homegrown problem

Regardless of the China situation, current variants in the U.S. are
likely more problematic. At least in the short-term.

Specifically, we have a new subvariant on the horizon: XBB.1.5. This
is an offshoot of BA.2, which is different from the subvariant
currently circulating (BQ.1.1— an offshoot of BA.5).

[[link removed]]

Phylogenetic tree with scale bar indicating genetic distance,
from Wang et al
[[link removed]],
Cell

Both lab and epidemiological data show XBB.5.1 may be cause for
concern:

Source: Graph from JWeiland
[[link removed]],
Analysis from Trevor Bedford

*
In the “real world,” and particularly in New York, cases are
exponentially increasing. Currently XBB.1.5 has a 120%
[[link removed]] weekly
growth advantage, which equates to, on average, 1 infected person
infecting 2 others. This rate is higher than we’ve seen with any
other subvariant this year given our immunity wall.

[[link removed]]

So, as expected, we see a clear uptick in Northeast wastewater. This
is unwelcome given that admissions for people over age 70, for
example, are the third highest 
[[link removed]]since
the pandemic began. This doesn’t reflect the new variant or impact
of holidays, yet, either.

[[link removed]]

U.S. Covid-19 Wastewater Monitoring by Region. Yellow=Northeast; Pink=
South; Green= West, Purple=Midwest (Source: Biobot Analytic
[[link removed]]s)

*
In the lab
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XBB.1.5 is presenting a more confusing picture. It has a similar
ability to escape our immunity as other subvariants. Because of this,
we wouldn’t think it would cause a massive wave compared to what is
circulating right now. XBB.1.5 _does _have higher ACE2 binding
affinity—it allows it to latch onto our cells better; it’s more
sticky—but that wouldn’t necessarily cause it to be more
transmissible. So something else may be going on—another part of the
virus may have changed that influences transmission. We need to look
into this more.

Bottom line

We should be very concerned for the people of China. And it is
possible that a variant of concern will arise from their disaster. But
the U.S. already has a problem of its own.

I was hoping for a quieter 2023. There may still be a chance, but
these are not welcome developments going into the New Year.

Love, YLE

_“Your Local Epidemiologist (YLE)” is written by Dr. Katelyn
Jetelina, MPH PhD—an epidemiologist, data scientist, wife, and mom
of two little girls. During the day she works at a nonpartisan health
policy think tank and is a senior scientific consultant to a number of
organizations, including the CDC. At night she writes this newsletter.
Her main goal is to “translate” the ever-evolving public health
science so that people will be well equipped to make evidence-based
decisions. This newsletter is free thanks to the generous support of
fellow YLE community members. To support this effort, subscribe
[[link removed]]._

* COVID-19
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* epidemics
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* China
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* vaccines
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* public health
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