Eric Topol is a professor of molecular medicine at Scripps Research.
The XBB strain is the first fast-spreading recombinant variant — meaning it is a fusion of two omicron lineages. Its original version led to a wave of infections in Singapore. Then it added two critical mutations to become XBB.1.5, which was first detected in New York.
These two mutations maintain the high level of immune escape of XBB, while also adding more infectivity advantage, giving the virus better ability to attach itself to the receptors that get it into our cells. The variant identified has rapidly become dominant throughout the Northeast and is destined to do so across the country in the weeks ahead.
What’s more, it is picking up steam in many European and Asian countries. This tells us that XBB.1.5 is no slouch. It is outcompeting a soup of new omicron variants that have arisen in recent months.
While there is no indication that XBB.1.5 is more pathogenic or virulent, its ability to spread seems striking, given how quickly it rose to dominance in New York and contiguous states. XBB.1.5 now comprises well beyond 75 percent of infections in New York, Connecticut, New Jersey and Massachusetts. Hospitalizations have risen among seniors to levels only the first omicron wave surpassed.
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Of course, it is hard to solely attribute this to XBB.1.5, given the population’s waning immunity, less frequent use of masks and other mitigation measures, and indoor gatherings during the holiday season. But the spike in hospitalizations in these states is significantly greater than in other regions in the country. And it is people 65 and older who, along with the immunocompromised, are the most vulnerable.
What can be done to defend against XBB.1.5? It is essential to get boosted, as new data from the Centers for Disease Control and Prevention show. Those who are 65 and older who received the bivalent vaccine are 80 percent less likely to be hospitalized. Furthermore, there is evidence that the bivalent vaccine — even though it targeted the earlier BA.5 variant — helps induce neutralizing antibodies and broaden immunity against XBB.1.5. Beyond boosters, the use of high-quality masks, rapid testing before gatherings, distancing, air ventilation and filtration will all help protect against infections.
Americans can take some comfort in the combined immunity from the country’s massive numbers of infections, reinfections, vaccinations and boosters. That should blunt the effect of XBB.1.5. Still, we have already seen the levels of covid hospitalizations in the United States reach their highest level in almost 11 months, and we’re not done with this wave yet.
The implications of XBB.1.5 are also much bigger than just this formidable variant. The virus is talking to us, and it is telling us it has many more ways to evolve. It is revealing that it not only can fake out or elude our immune response, but can also get better at penetrating our cells. What will happen next? Will we see a whole new family of variants arise that are distinct from the omicron family? It is entirely possible.
And we’re not ready for it. Genomic surveillance around the world has dropped 90 percent since early 2022, as reflected by sequenced samples deposited at the Global Initiative on Sharing Avian Influenza Data. That’s unacceptable. China is in the midst of a covid crisis with unmitigated spread, and it could become a breeding ground for functionally important variants in the months ahead.
Worse, there’s no coordinated, high-priority, accelerated or even funded efforts — either in the United States or globally — to develop the next-generation vaccines that will block infections, such as universal, variant-proof vaccines with extended duration of protection. Nor do we have drugs to replace the monoclonal antibodies that no longer work or for Paxlovid, in case resistance emerges to that treatment.
We’ve moved from complacency to frank capitulation at just the wrong time. If XBB.1.5 is telling us one thing, it’s that we can’t be oblivious. We’re all tired, but we’re up against a force that isn’t. We have the intelligence, resourcefulness and ingenuity to finally get ahead of the virus, but politics and unwillingness to invest are holding us back. We cannot afford that gridlock.