Omicron variant: Recent study on transmissibility is not ‘remotely conclusive,’ virologist says

University of Saskatchewan Vaccine and Infectious Disease Organization Virologist Angela Rasmussen joins Yahoo Finance Live to discuss the latest on the coronavirus and the Omicron variant.

Video transcript

AKIKO FUJITA: A new study out of Japan points to some troubling findings around the omicron variant. That study from a Health Ministry advisor says the new strain is four times more transmissible than delta. That comes as more than 40 people in the US have now tested positive for this variant. Let's bring in Angela Rasmussen. She's University of Saskatchewan Vaccine and Infectious Disease Organization virologist.

We've also got Yahoo Finance's Anjalee Khemlani joining in on the conversation. Angela, it's good to talk to you today. We've got this study out of Japan, this coming a day after, though, Pfizer said, yes, in fact, their booster shot offers significant protection from the variant. So how should we be looking at this new threat?

ANGELA RASMUSSEN: So I think we really need to be very careful when looking at these estimates, such as the ones from the analysis from Japan. That study was based on a mathematical model from data from South Africa. And while that does suggest that in that population, omicron rapidly displaced delta, there already wasn't a very high background of delta to begin with.

So that's really not the situation that we're looking at in the US and in Europe, in places where there have been large delta surges, and delta continues to circulate. So I think we really do need to be very careful. We should assume that this may be more transmissible than delta, but I don't think that is remotely conclusive yet. So I think we still need to keep watching and waiting and take precautions in the meantime.

ZACK GUZMAN: We've been hearing a lot about the way that doctors have been talking about this one, Angela, and when we think about maybe the way that this variant could be a positive step, we talked a lot about deaths. And that was the thing that we all wanted to avoid when we were thinking about getting vaccinated and reducing the weight on the hospital staff here. I mean, what do you make of maybe the way that some of the cases that we've been covering recently have not been as dire as maybe some of those ones we saw earlier? Is that all due to vaccination? What's your take maybe on how that could be the positive silver lining here?

ANGELA RASMUSSEN: So this is really the big mystery right now. And I think everybody's really cautiously optimistic that the fact that hospitalization and death, which is normally a lagging indicator, has not really caught up with the increase in cases in South Africa. That probably points to the pre-existing immunity ameliorating some of the disease severity. So that's a very positive sign. But I think people, again, need to be really, really careful at assuming that this is going to be the situation in other populations.

There are other factors in South Africa specifically that may lead to us assuming that there is a milder course of disease in people who have either been infected previously or vaccinated. And that is that the population in South Africa is actually much younger than many of the populations in places that have been dealing with large delta surges.

So these people are generally going to be more inclined to be lower risk for severe COVID after infection with any variants. I, like everybody else, am really hoping that this holds up and that this is, in fact, an effect of immunization because that really does bode well for how the omicron wave that looks like it's upon us will ultimately play out.

ANJALEE KHEMLANI: Angela, Anjalee here. I know that we've also been looking at what's happening over in Europe. They're experiencing a delta surge, largely speaking. But do we expect that omicron could give us that same level of surge? And even though, we do have pretty significant vaccinations, as well as the prior infections as well, even though the South Africa study did show a little bit of possible breakthrough there, do we anticipate that we might have to reinstate a lot of restrictions here in the US?

ANGELA RASMUSSEN: So I think that really is the million dollar question right now. And without a doubt, all of the data that is coming out does suggest that there's going to be a much higher likelihood of breakthrough infection or reinfection in people who were previously infected with other variants with omicron. That, to me, seems very, very clear. What seems less clear to me is whether or not omicron is actually going to be able to outcompete and overtake delta. As I mentioned before, in South Africa, they had just gotten over a big delta wave, but overall prevalence was relatively low. So it wasn't very difficult for omicron to displace that in that population.

In many places in Europe and in the US, there's still a ton of delta circulating around. And I think that it really is going to be the test of omicron to see how omicron fares when it's put head to head with delta. It's totally possible that omicron may outcompete delta and become the dominant variant. I think it's also completely possible that delta will maintain its status as the dominant variant in the global setting. And omicron will cause regional outbreaks, but not necessarily overtake delta. So this is one thing that I think everybody's watching really, really closely.

ANJALEE KHEMLANI: I want to touch on the prior infection part because I know a lot of people have been citing that as a reason not to necessarily really worry as much sometimes. But looking at what we've seen from that South Africa study, as well as just generally speaking, the way that it's transmitting, do you anticipate that we might in the future also have to continue worrying about this, where prior infection isn't necessarily a good blocker for the variant?

ANGELA RASMUSSEN: Yeah, I think this is something that we've been sort of struggling with for a long time. And some of it has to do with mixed messaging. I think a lot of people think, well, I've already had COVID. Why do I need to get the vaccine on top of that? I will say that the one thing that the recent data on antibody neutralization with omicron makes very, very clear is that vaccination on top of a prior infection is most protective. And that will probably apply to booster doses of the vaccines as well.

So it does look like three exposures, whether through vaccination or infection, are really important for your immune system to develop the repertoire of neutralizing antibodies that can really significantly reduce the risk of omicron breakthrough. So I think that going forward, we're going to have to focus on encouraging people who have had prior infection to get potentially fully vaccinated or to get boosted, at least, with one shot.

And I think we really do need to also focus on encouraging everybody who has been fully vaccinated with an mRNA vaccine or a Johnson & Johnson adenovirus vaccine to get at least one booster shot going forward because it does really look like that booster is going to be required to prevent breakthrough infections with omicron.

AKIKO FUJITA: Anjalee, to the point that you made earlier, that there's a whole scale reassessment happening right now on the restrictions that have been in place, and it feels like to this point, we've largely separated the vaccinated from the unvaccinated. You've talked about how that should vary with isolation and quarantine as well. Does the omicron variant change that calculation?

ANGELA RASMUSSEN: I don't know that it does. And honestly, I think it really does remain to be seen how severe omicron ends up being and whether it can outcompete delta before we need to talk about applying new restrictions. I do think, though, that this is separate from the issue of isolation and quarantine. Now most countries have really not been able to enforce isolation and quarantine effectively, but many people through their businesses have tried to abide by the quarantine recommendations.

And I think they can be really punitive, especially if we're talking about breakthrough infections that really aren't going to pose a serious health risk to the person getting them, specifically somebody who's been vaccinated before. If somebody has a really mild, relatively self-limiting case of COVID-19 after a breakthrough infection with omicron or any other variant, I do think that we should consider applying more testing and allowing those people to leave isolation or quarantine once it's established that they're no longer a risk of transmission to others.

I think that in that situation, the real risk there is that somebody is going to go on and pass that infection on to people who may be more vulnerable, who may be unvaccinated. I really do think that we need to be smarter about this because it really is disrupting people's lives. And it's disrupting entire economies. So we really do need to think-- we are at the point in the pandemic, enough people are vaccinated and we do have the testing capacity, that we should really be thinking about applying smarter, not necessarily more stringent or draconian isolation and quarantine policies.

AKIKO FUJITA: Well, it's certainly good to get your guidance, as we learn more about this new strain. Angela Rasmussen, University of Saskatchewan Vaccine and Infectious Disease Organization virologist. And our thanks to Anjalee Khemlani as well for joining in on the conversation.