Dr. Shad Marvasti, Director of Public Health Prevention and Health Promotion at the University of Arizona College of Medicine in Phoenix, joins Yahoo Finance Live to discuss the latest on the coronavirus pandemic.

Video Transcript

- Well, half the adult population in the US is now fully vaccinated, according to the CDC. And for those people, the upcoming Memorial Day weekend may look a lot like prior holiday weekends pre-pandemic. But what about the unvaccinated? Joining us to talk about that and more is Dr. Shad Marvasti, Director of Public Health Prevention and Health Promotion at the University of Arizona College of Medicine in Phoenix. Dr. Marvasti, thanks for being with us. What are health experts recommending for people who are not vaccinated? You know, there might be a feeling that they can let down their guard with now half of the adult population vaccinated in this country.

SHAD MARVASTI: Yeah, the reality is, as the CDC director recently said, that the pandemic is not over and that the risk is still the same as it was at the height of the winter surge in January for those who are not vaccinated. So going into Memorial Day weekend, if you're not vaccinated, I would say you still have to practice the same mitigation measures of mask wearing and distancing, although that's been lifted in many parts of the country. And that's concerning to me. I'm not really concerned about the unvaccinated as I am about those who are unvaccinated.

Sorry, I'm not as concerned about those who are fully vaccinated but I am about those who are unvaccinated. And the reason being is that these folks were unvaccinated getting together, obviously, and the virus still circulating in the community creates a perfect storm for the development of new variants, which could be at some point resistant to the vaccines. And thankfully, that hasn't been the case yet, but there's no reason to believe that that won't happen.

- So doctor, taking what you're saying-- and let's just carry it out a little bit further down the timeline, right? So we have half of American adults right now are vaccinated. But the pace of those vaccinations are slowing down. So a lot of the folks that are outstanding have some form of vaccine hesitancy. So what you're saying, that you're more concerned about the unvaccinated than the vaccinated. If we never reach herd immunity, which we've heard a lot of doctors say that we won't, will those unvaccinated folks still have to remain mask wearers six months from now, a year from now?

SHAD MARVASTI: Absolutely. I think that's the problem here is that we have a false sense of security right now, because if you look at the numbers, you know, we're half of US adults, which is just only 40% of the total population. We need to get to about 80% or 260 million. If you consider the total number of cases of 33 million known cases of COVID, and they all have some kind of natural immunity, you add that to the 130 million that are fully vaccinated, you get to about 166 million. But people know now that that 33 million of people who have recovered is really probably two to five times higher. Let's say conservatively it's three times higher. So that would mean 100 million people who've been exposed and recovered and have some kind of natural immunity. Add that to 130 million that gets you basically to 230 million, which is nearly 70% of the population, which is the reason why right now we're seeing lower numbers.

We've had the lowest numbers right now since March of 2020. So I think that lulls us into complacency. But we know that people who are unvaccinated, even if they've recovered from COVID, their immunity doesn't last as long as those who have been vaccinated. So it's only a matter of time, if they don't get vaccinated, where they're going to be susceptible and the new variants will be there. And then we're going to have to start all over again. And that's really my concern.

- Well, based on what you just said-- and this is where there is a lot of gray area and things can get confusing for folks. You're going to have family and friends gathering this weekend, in some cases for the first time in a very, very long time. If within that group you have some vaccinated folks, and then some folks who have recovered who had COVID and have recovered, but are not vaccinated, but have this natural immunity, is that a better situation to be in than if you put vaxxed and completely unvaxxed non-COVID people together?

SHAD MARVASTI: Yes, it's definitely a better scenario, I would say within a three-month window. Outside of the three-month window of when you were diagnosed and recovered from COVID, we don't know if you have immunity. We know that immunity from the vaccine lasts at least six months. We also know that people who have had COVID and recovered, if they get vaccinated, the amount of antibodies in their system and immunity increases by 10 times. And even people with long COVID, we're seeing now clinically that their symptoms improve if they get vaccinated. So all the more reason to get vaccinated and actually to require some kind of vaccine passport. I know it's not popular. But if we incentivize people for getting involved in more public activities, higher risk public life, community life, by having them get vaccinated and checking vaccine status, we'll do a lot more to protect people. And remember, all of our children at this point, except for those above the age of 12, who are starting to get vaccinated, all of the children under 12 are still not vaccinated. So we also have to protect them as well.

- All right, Dr. Shad Marvasti, a complicated holiday weekend on the horizon, for sure. Thanks so much for your insights today.