The Rise of XBB
Volume 7, Issue 1 | January 4, 2023
In This Issue
COVID vaccines have saved millions. Stop bashing them.
Surge in China leads to travel testing policy change
A GI test that listens
One place where COVID isn’t in the top 10
New and Noteworthy
XBB conquers the US, fast
The BQ reign ended up being pretty short. In the last three weeks of 2022, the XBB family went from 7.6% of cases to 44.1%, stopping the BQs’ rise dead in its tracks, as shown in the CDC’s variant Nowcast below.
The driver of this speedy takeover is primarily subvariant XBB.1.5. Its edge comes from exactly what you’d expect: a significant increase in both immunity escape and transmissibility. (@jbloom_lab gives a good overview in this thread.) As of last week, it had a 120% weekly growth advantage (on average, one person infects two others), which, Dr. Katelyn Jetelina warned, was the highest for any variant in 2022.
XBB.1.5 achieves its overall superiority versus XBB.1 largely from a change in a single amino acid, which in this case required two mutations right next to each other (for an excellent explanation see Ryan Hisner’s thread). A two-mutation change like this is extremely rare in RNA viruses.
While we haven’t yet seen any increase in mortality since the XBBs took charge (see above), that’s always the laggiest indicator - and we have to factor in the reporting delays that come with holidays. Fingers crossed.
There’s no justification for ongoing resistance to COVID vaccines.
Commentary: COVID vaccines have saved millions of lives during the pandemic, and yet resistance to them continues. Recently CDC provided an update to COVID vaccine effectiveness statistics, using data through late October 2022. Digging into the details, we see some striking highlights:
The relatively lower virulence of Omicron relative to other variants, plus the increase in immunity due to both vaccination and previous infection has reduced the risk of death for all. That includes even unvaccinated people in the vulnerable 65-79 age group (see charts below) – the risk of death in this group is 33.7X lower now than it was at the beginning of January 2022.
Vaccination continues to provide a significant reduction in the risk of death from COVID – for that same vulnerable 65-79 age group, the bivalent vaccine reduces the risk of death close to zero.
Net net, fully vaccinated and bivalent boosted 65-79 year olds are now at 37.6x lower risk of death than the unvaccinated in this same age group.
Changes in China → changes in COVID testing for travelers
Over the last three weeks, China’s COVID policy has taken a 180. After public protests about its zero-COVID policy and that policy’s aggressive restriction of people’s movements, the nation lifted almost all restrictions - without increasing vaccination rates or health-care capacity. The result has been a worst-case scenario - a massive increase in cases and deaths. How many? Hard to know actual numbers, as little data is being released from China, but from what we see and hear from social media is that hospitals and morgues are overflowing.
This explosion of infections caused the CDC to issue a requirement for all travelers from China (directly or through another country) to show proof of a negative COVID test within 48 hours of boarding a flight to the US.
Food for Thought
Listening to your body…literally
Maybe this should not be listed under “Food for Thought,” or maybe you should not read this after having a big meal! But in our quest to share information about new and interesting diagnostic tests, we simply couldn’t resist this one. It is an app that listens to bowel movements and assesses whether they’re normal or not, based on the sound.
As an initial use case, the app is meant to be implemented not in your (or our) home bathroom, but in public bathrooms where cholera may be present. Cholera’s hallmark is an extremely . . . sonically distinctive kind of diarrhea, and early detection of an outbreak can help local hospitals be more aggressive with suspected cases.
EUA Update
The FDA issued seven new EUAs, 16 amendments to existing EUAs, and eight new safety communications in December.
New EUAs (7):
COVID Molecular (1): OnsiteGene, Inc.
COVID Antigen (4): ACON Laboratories, Inc. | CTK Biotech, Inc. | Advin Biotech Inc. | Oceanit Foundry LLC
COVID Antibody (1): Diazyme SARS-CoV-2 Neutralizing Antibody CLIA Kit
Respiratory multiplex (Flu and COVID) (1): Visby Medical Respiratory Health Test
Amendments to Existing EUA’s (16):
Molecular (7)
Antigen (9)
Safety Communications (8):
Warning Letters (2): Empowered Diagnostics LLC | Alternative Health Distribution LLC
Revocations (6): MD Anderson High-throughput SARS-CoV-2 RT-PCR Assay | Visby Medical COVID-19 Point of Care Test | Visby Medical COVID-19 |SARS-CoV-2 DETECTR Reagent Kit | Mammoth DETECTR BOOST SARS-CoV-2 Reagent Kit | University of Arizona COVID-19 ELISA pan-Ig Antibody Test Note: All revocations above were initiated at the EUA holder’s request.
Quick Hits
COVID did not make the Top 10 Google health related searches of 2022. Hard to say if this is good or bad news. Best case - people think that they know what to do and don’t need anyone explaining it again.