Efforts to update COVID vaccines can't seem to keep up with changes in the virus itself.
State of play: New variants appear to be even more immune-resistant than the original Omicron strain, raising the possibility that even retooled vaccines could be outdated by the time they become available this fall.
Driving the news: Preliminary data suggests that the most recent Omicron subvariants are significantly different from the original version that began spreading late last year.
- One preprint released last week found that BA.4 and BA.5, which originated in South Africa, are substantially more resistant to antibodies — compared to an earlier strain, and also to the one that's dominant in the U.S. right now — and thus more likely to lead to breakthrough infections.
- Other preliminary research has found that the latest subvariants are more pathogenic and can potentially evade even the immune protection that comes from a previous Omicron infection.
The big picture: Clinical trials are underway to study tweaked versions of the Pfizer and Moderna vaccines, and the FDA has said it will decide this summer whether to recommend these updated versions for use later this year.
- A leading option is to target multiple variants, including Omicron, with the same vaccine. But the Omicron version that's around in a few months may be significantly different than the strain the vaccine was designed to target.
Between the lines: Although the vaccine manufacturers have said they can quickly adapt to produce new vaccine versions, collecting data on those vaccines' effectiveness through real-world clinical trials takes time.
- "It takes six months for the omicron BA.1 vaccines to be properly tested and then longer to produce them. That's inevitable," Cornell virologist John Moore said.
What they're saying: "It's unclear what the mix will be in the vaccine that's used in the fall, but there's a very good chance that it'll be against the original Omicron," said Celine Gounder, an infectious disease specialist and KHN editor-at-large.
- "But it's really unclear that it's going to be much of an improvement versus the original vaccine when BA.4 and BA.5 are so significantly different than the original Omicron."
- "It's pretty challenging. We're very much behind the virus given the speed at which it's moving," Gounder added.
Yes, but: The jury is still out as to whether an Omicron-specific vaccine has significant benefits compared to the original version in the first place.
- "I'm not convinced they are going to be a meaningful upgrade anyway," said Moore, who also thinks the two latest subvariants "are not game changers."
- Three doses of the existing vaccines are still very good at preventing severe disease and death, despite the drop in effectiveness against infection.
The bottom line: Keeping up with a virus that is evolving this quickly is inherently in tension with collecting the data traditionally required to make big regulatory decisions.
- In this case, the implications are likely relatively minor. But if a more dangerous variant that requires new vaccines emerges, the current situation suggests that very tough choices will have to be made.
