The extent to which Omicron's rapid spread leaves the world better off in its fight against COVID depends on a few big questions, including how long infection-induced immunity actually lasts.
Why it matters: Vaccinations and infections at high enough levels can form an immunity wall against the future spread of the virus.
- But if Omicron infections ultimately don't contribute much to this wall, that leaves much of the world still vulnerable.
The big picture: When the coronavirus first emerged, no one had any immune protection to it. In the two years since, that's changed drastically, as hundreds of millions of people around the world have become infected and billions have been vaccinated.
- It'd be a potential silver living if the Omicron variant's soaring global caseloads raised the level of global immunity to the point that the virus isn't able to easily spread.
- But for that to happen, Omicron infections would have to translate into significant additional protection against future infection — which isn't a given.
State of play: There are outstanding questions as to whether the immune protection generated by Omicron infections is substantial or long-lasting.
- It may also have limited effectiveness against other variants, particularly because Omicron is so different from those that originated before it. It thus may be significantly different than whatever comes next.
- Omicron can easily reinfect people who have already been infected with other variants, and can also escape immunity created by vaccines based on the original version of the virus. Reinfection is likely to work the other way too, said Cornell virologist John Moore.
- That means that for someone who hasn't been vaccinated or previously infected, "an Omicron infection isn't going to give them much protection against a future variant that isn't Omicron-like," Moore said. "It's not nothing, but it would be comparatively weak.”
The other side: For people who have been vaccinated or infected with another variant — which is a very sizable population at this point — an Omicron infection could end up working as an effective booster.
- "It comes down to cross boosting. What's that going to look like?" Moore said, cautioning that we need much more data. "So far we've seen only bread crumbs and I want to see the whole loaf.”
The intrigue: It's also unclear how well an Omicron infection protects against future Omicron infections, partially because it causes less severe disease than other variants. Milder infections generally lead to weaker immune responses.
- "It appears that the immunity conferred by infection from Omicron isn't that durable," former FDA commissioner and Pfizer board member Scott Gottlieb told CNBC.
- "It's more of an upper airway infection. We see less durable immunities with upper airway infections," Gottlieb said. "Since it's a less severe infection, it's not inducing as robust of an antibody response and an antibody-induced immunity."
Zoom in: Recently posted preprint papers — which have not yet been peer-reviewed — have offered some clues.
- One, for example, concluded that "Omicron-induced immunity may not be sufficient to prevent infection from another, more pathogenic variant should it emerge in the future. They also highlight the continued importance of vaccine boosters in enhancing immunity."
The bottom line: While natural immunity has value, Omicron appears to be proving once again that vaccines are still the most effective tool at our disposal.
- "Heading into the fall, we're probably going to need to contemplate revaccination if you want to maintain your immunity," Gottlieb said.
- And billions of people around the world have yet to receive their primary vaccine doses, which remain significantly effective at preventing severe disease — even against Omicron.
