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Exploring the Continued Need for COVID-19 Vaccines and Boosters - Episode 3

Mitigating Population Risk for COVID-19

Drs Rothholz and Goad discuss population health strategies for COVID-19.

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Mitchel Rothholz, RPh, MBA: Is there a level of antibodies that says you’ve got the right protection? We talked about waning immunity. The question that always comes up is: what is the right level that people should be at? We’ll talk in a little while about boosters. We say the protection is waning, but how do we know what that level is?

Jeff Goad, PharmD, MPH: Unfortunately, the answer is fully unsatisfactory. We don’t have a good clinical correlate. For many diseases, we don’t. For example, with influenza, you can’t measure an antibody level and say whether you’re going to be protected. There are a lot of variables. With some diseases, such as hepatitis B, we have a distinct threshold. We know that above 10 mIU/mL, you would be protected. Unfortunately, the science is still evolving in regard to whether there’s an antibody level that we can measure that would predict that you’re protected against a disease.

In studies, or when they’re talking about waning antibody levels, it’s always in relation to something else. It’s called relative antibody risk. If you’re trying to compare 2 vaccines or vaccinated with unvaccinated, you’re just comparing the 2 in their magnitude of which one is greater than the other. There’s no actual threshold that we can use clinically to say whether you’re protected. Hopefully we’ll get to that level one day, but we aren’t there.

Mitchel Rothholz, RPh, MBA: Great points, Jeff. Thank you. One reason we’re doing vaccinations, whether it’s COVID-19 or influenza, is to protect against the serious outcomes of the disease. That’s one of the major measurements of our success of our immunization programs: Are we reducing the number of severe illnesses, hospitalizations, and deaths in our population? Besides tests, what are some things that pharmacists and the health care community need to monitor in terms of knowing when certain measures need to be taken? For example, when you need to do a more intense PPE [personal protective equipment] approach to infection control, what things should they be looking for?

Jeff Goad, PharmD, MPH: As with the recommendations for testing and vaccination, they’ve changed rapidly. There were different scales and color-coding systems that the CDC [Centers for Disease Control and Prevention] put out to help people understand the population risk. People need to keep in mind individual risk and population risk. For example, if you’re immunocompromised, your risk is different from the rest of the population. You have an individual risk that the CDC also addresses in vaccines and use of higher-quality PPE, for example. But the population risk that we’ve tried to use has gone through different color coding and focus within the CDC, state health departments, and local health departments.

The one that we’re sitting with right now focuses on community levels of transmission. It puts it in high, medium, and low [levels]. The idea is to arm employers, you, school districts, and others with an understanding of how to grade your protection strategies. For example, when do you go remote for certain activities? When do you recommend masks? Does that mask recommendation increase in terms of N95 and KF94s vs surgical level 1 through 3–type masks or cloth masks? With all these things that we have available, the science and the recommendations have evolved to make it a little more operational. It’s like when you walk into the airport and TSA [Transportation Security Administration] says we’re at an orange level or purple. The colors mean nothing if you don’t know what those mean.

With the pandemic, as we possibly move to this endemic state, we’ve gotten to a system to help people understand what we’re focusing on now: how we keep society functioning so that our hospitals aren’t overwhelmed. Our metrics look at hospital admissions, percentage of staff, and inpatient beds for COVID-19. If all your beds are taken up with patients with COVID-19, that means if you get in an accident or if you have a heart attack, there’s no bed for you. That isn’t helpful in a functioning society.

[It’s important] to try to use this graded system so that people know rates are ticking up. For example, if we have a winter surge, you might see those rates swing up to high in many places that are experiencing low community transmission of COVID-19. They need to be able to reinstate some of those restrictions and personal prevention strategies, such as masking, avoiding crowded areas, increase in testing, screening testing, and serial testing. We have all these things, and now we have a system in place. If people would operationalize that with their employees, school districts, and all kinds of different congregate settings, you’d have a strategy that people could raise up or scale down depending on what the pandemic is doing. That’s a level of control we didn’t have before, and we need to take advantage of it.

Mitchel Rothholz, RPh, MBA: You make a great point about keeping our vigilance in terms of monitoring. One concern that a lot of folks have is complacency being built into the thinking of providers and the community. The NIH [National Institutes of Health] just released a statistic that about 80% of unvaccinated patients with COVID-19 had mild symptoms. A lot of people look at flu the same way: “I’m not going to die from flu. I may get sick, but I’ll get through it. Why should I get vaccinated?” Give me your sound bite that you give patients when they bring up that concern.

Jeff Goad, PharmD, MPH: The data are still there, although we had slightly different messages for each wave as we went through Alpha, Beta, Delta, and Omicron, because the virus is changing. It’s silly to assume that we can use the same strategies and think about the virus in the same way as it keeps mutating and coming up with different ways to evade our vaccines and defenses. You have to change that message. That’s sometimes where unvaccinated people or a certain portion of our population that’s skeptical of science would say, “You’re changing your messages.” No, we’re adapting our messages. You have to adapt the message to the changing environment. Omicron and Delta were much more contagious, with Delta having a greater level of severity.

As we start to adjust our strategies for community-level transmission, focusing on hospitalizations and death as our primary focal point for getting this under control began to change. People have to understand that you still might get infected. Fortunately, the virus has been evolving—keep in mind, this virus can take a left turn or a right turn at any time—to become more contagious but less severe. If you were to personify a virus—which is dangerous sometimes, but the analogies sometimes help—a virus is probably more successful if it can spread faster to more people and if it doesn’t cause severe disease, such that you don’t stay at home, you go out in the community and want to spread it more. That virus is probably going to be more successful. Those mutants, those variants that end up doing something where it makes it more contagious and less severe, are more likely to survive.

However, variants of concern that come down the pipeline as we look across the world can take hold very quickly. It can take a left turn and become more severe and more contagious just as easily, so we need to keep an eye [out for them]. One great system that came out of the pandemic is our global surveillance systems. They’re amazing now. We didn’t have these in place before. Hopefully we can learn from this, keep those surveillance systems, and apply them to other diseases so we can be ready for the next variant that heads our way.

Transcript edited for clarity.

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