Thread by @celinegounder

1/ Today I joined @DrPaulOffit & @angie_rasmussen on
@NPR @wamu885's @1a with @jwhitepubradio to talk about the XBB.1.5 COVID variant & more.

the1a.org/segments/vacci…

2/ Some key takeaways for you, starting with some basic definitions:

Monovalent: a COVID vaccine against 1 COVID variant, currently the original Wuhan variant

Bivalent: a COVID vaccine against 2 COVID variants, currently the original Wuhan variant + the BA.5 Omicron subvariant

3/ What does it mean to be fully vaccinated against COVID?

2 doses of Pfizer / Moderna vaccine
OR
1 dose of J&J vaccine

But...

4/ What does it mean to be up-to-date with COVID vaccinations?

Most people:

4 doses of Pfizer / Moderna vaccine (including 1 dose of the updated bivalent booster)
OR
1 dose of J&J vaccine + 2 doses of Pfizer / Moderna vaccine (including 1 dose of the updated bivalent booster)

5/ What if you're immunocompromised?

4 or 5 doses of Pfizer / Moderna vaccine (including 1 dose of the updated bivalent booster)
OR
1 dose of J&J vaccine + 2 doses of Pfizer / Moderna vaccine (including 1 or doses of the updated bivalent booster

6/ If you've gotten a bivalent booster, do you need more boosters?

Not at this time.

However, high-risk persons including immunocompromised people, elderly people, & pregnant women, should anticipate that they will need more COVID boosters in the future.

7/ But won't boosters reduce your risk of infection?

Boosters reduce your risk of infection imperfectly & transiently.

COVID vaccines are designed to prevent progression to severe disease, hospitalization & death, not to block all infections.

8/ Won't boosters reduce your risk of transmitting onward to others?

Prior immunity from vaccinations or infection reduces transmission by ~25%.

Prior hybrid immunity from vaccination + infection reduces transmission by ~40%.

nature.com/articles/s4159…

9/ But what about long COVID?

Prior immunity from vaccination or infection protects against long COVID.

But if you get your immunity through infection, you also run the risk of getting severe COVID or long COVID from that infection.

10/ After 2-3 COVID vaccinations, the protection against long COVID seems to plateau:

https://twitter.com/celinegounder/status/1572617903333048320?s=20

11/ To further reduce the risk of long COVID, we would need to think more holistically & show some imagination:
theatlantic.com/ideas/archive/…

12/ The Omicron subvariant XBB.1.5 now accounts for over 40% of US COVID cases.

XBB.1.5 resulted from recombination between prior Omicron subvariants.

13/ XBB.1.5 is as immune evasive as XBB.1, but it binds cells more strongly.

The fact that XBB.1.5 is outrunning XBB.1 suggests that how strongly the viruses binds to cell surface receptors plays an important role in the spread of the virus.

14/ Singapore saw a surge in cases with XBB, but not a surge in hospitalizations & deaths.

But Singapore has a higher rate of vaccination & boosting than the US.

In particular, less than 40% of people 65+ in the US are up to date with their boosters.

This is a huge liability.

15/ But let's compare Illinois & New York.

New York has a lot of XBB.1.5 (dark purple in the pie charts).

Illinois doesn't.

16/ Wastewater data show an increase in COVID transmission throughout the country, whether or not there's a lot of XBB.1.5.

17/ And COVID hospitalizations are up in both Illinois & New York even though Illinois doesn't have much XBB.1.5 while New York does:

18/ What does this mean?

It's unlikely that XBB.1.5 is the primary driver of increasing COVID cases & hospitalizations.

19/ So what's driving the increase in COVID cases & hospitalizations?
🔹Travel & socializing over the holidays
🔹Lack of masking, ventilation & air filtration, & testing
🔹Undervaccination
🔹Waning immunity, especially among elderly people who haven't gotten boosted