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Home » New XBB variant of COVID-19 — bivalent booster vaccine works

New XBB variant of COVID-19 — bivalent booster vaccine works

Here we go with a new, kind of scary version of COVID-19 — the XBB variant, which is just one of several variants that are spreading across the world. I think we’ve heard and read about so many variants over the past two and a half years that it might appear to be background noise.

But the new XBB variant probably shouldn’t be ignored — it spreads faster and seems to evade the immune system. These two issues alone can become problematic as we enter the winter months.

This article will look at this variant (though I’m just picking on one out of dozens that appear to be circulating) because XBB seems to be a bit more virulent than others. But there’s good news too — the new bivalent COVID-19 vaccine boosters from Pfizer and Moderna appear to protect against the new variant.

vaccine bottle in close up photography
Photo by Maksim Goncharenok on

What is the XBB variant?

XBB is a descendant (one of at least 300) of the original Omicron strain of SARS-CoV-2 that arose in late 2021. These new strains appear to originate from genetic drift, something we see with the influenza viruses. Of course, this kind of drift occurs over a few years with the flu but is crammed into a handful of months with COVID-19.

XBB hit Singapore this week, causing daily cases to go from 4,700 on 9 October to 11,700 on 10 October, a massive increase.

What makes this variant particularly scary is that:

  1. It’s more infectious than other variants.
  2. It avoids the immune system. Those individuals who have not gotten the booster vaccines may be at higher risk. And immune therapies, such as monoclonal antibodies, may not work for those who contract this variant.
a person holding white labeled bottle
Photo by Maksim Goncharenok on

Good news

However, as I wrote above, the bivalent booster vaccine that was recently approved in the US and other countries appears to give strong protection against the XBB variant. Now just to be absolutely clear, the booster vaccines will not prevent all infections and hospitalizations, but they should significantly reduce the chance of severe infection potentially leading to hospitalization or death.

I know that the uptake of the new bivalent booster has been quite low in the USA (although when I got my booster, there was a significant line of people of all ages).

So, if you need motivation for getting the booster, here you go — a new, more dangerous variant may be coming our way.

What we don’t know

Right now, the XBB variant is just centered in parts of Asia, Singapore and Hong Kong. It’s possible that any number of factors could keep the variant centered there. But who are we kidding? COVID-19 seems to break all the rules, and with packed international flights back to pre-pandemic levels, there is little reason to think that this variant won’t land in the USA and Europe during the next few days or weeks.

We also have very little understanding of the infectiousness of the variant. With just information from Singapore, it appears very infectious, but that’s one small data point. And you loyal readers know what I think about small sample sizes.

I have my bivalent COVID-19 vaccine booster, so I’m feeling like my immune system is prepared for the worst. Then again, there are 300 Omicron subvariants floating around the planet, so who knows what might be around the corner?

Michael Simpson

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