Pharmacist-Led Patient Education for COVID-19 Testing
Pharmacists play a significant role in patient education regarding COVID-19 vaccines.
Mitchel Rothholz, RPh, MBA: The high respiratory disease season is during the fall. Besides COVID-19 concerns, what other things are floating in the communities that are preventable through vaccinations?
Jeff Goad, PharmD, MPH: As an example, pneumococcal disease is the No. 1 secondary complication of influenza, although it doesn’t have a seasonal pattern. We think about vaccinating high-risk individuals, patients over 65 years old, as well as those with cardiac, pulmonary, endocrine, immune compromise, and comorbid conditions to help protect them against those respiratory bacteria. But it’s also vaccine preventable. Think about the things that you can cut down on, even from pediatric diseases, such as making sure our children are up to date on their measles, mumps, and rubella [vaccination], and the respiratory viruses that are easily controlled with adequate vaccination levels. To your point, vaccinate what we can, and protect and prevent against the rest through medications or masking in appropriate situations. We have strategies. We just need to put them into play.
Mitchel Rothholz, RPh, MBA: Hopefully soon, we’ll have another vaccine for RSV [respiratory syncytial virus]. There will be additional protections for communities. You hit on an important point for our audience to keep in mind. The symptoms for a lot of these respiratory diseases are similar. [It’s important to] be able to tell the difference between them based on symptoms and tests that may be available.
Let’s talk a little about tests. Testing was really big early on in the COVID-19 pandemic, and it continues to be important. But we’re also seeing a lot of impact on testing in communities. A lot of testing is still going on, but there have also been a lot of questions raised in terms of positivity of test results. Here’s a little insight in terms of the prevalence of positive tests. We’re also seeing delayed positivity—somebody tests negative and then takes another test and becomes positive. What’s going on there?
Jeff Goad, PharmD, MPH: Even from the early parts of the pandemic, [it’s important to] learn how to acquire an appropriate sample. A lot of pharmacists remember the very long nasal swab that had to go in the back of your brain to get the nasopharynx. As we learned more about where the virus concentrates—more in the upper respiratory tract, especially in the nares—we changed it to the swab pattern that we have for the PCR [polymerase chain reaction]. They’re called nucleic amplification tests—they pick up on very small pieces of virus—as well as our antigen tests. Both of these are viral tests. The antigen tests are looking for a little more. You have to have more virus, and it’s probably better for when people are symptomatic or when you need to trust a positive result.
Early on, and still today, people oftentimes test too early. For example, looking at Omicron vs Delta, Omicron may present quicker with symptoms, but the viral load isn’t there yet to pick it up on an antigen test. You’d probably pick it up on a PCR, but you aren’t getting it on an antigen test. For example, doing serial testing, where you give an antigen test—your point-of-care or home test—and then 48 hours later do another test to confirm that it was negative. If it’s positive, it’s probably positive. It has a very low false-positivity rate. That’s good when you’re trying to pull positives out of the community, but it doesn’t help you very much if you get a negative. That’s why, for the longest time, if you had symptoms and you [tested] negative, you were presumptively positive. The symptoms are there, which means that maybe the viral load isn’t there to hit the limit of detection. People need to follow the guidelines in place from the CDC [Centers for Disease Control and Prevention] to understand their isolation and their use of the test at appropriate intervals.
Mitchel Rothholz, RPh, MBA: Should somebody be concerned if they test negative and then positive, and then they continue to test positive? What would be your advice for our audience to tell patients when they have those results?
Jeff Goad, PharmD, MPH: Follow guidelines, because then you don’t end up making decisions based on tests that you don’t know what to do with. When I was training, one of my favorite physicians had a saying: “You deserve every test you order.” Make sure you order the test, or you perform the test if you’re a patient at home or if you’re a health care provider doing it at the appropriate intervals. Wait 3 to 5 days to test a patient who’s asymptomatic. Immediately test somebody who’s symptomatic. Look at the 5-day marker, although our isolation guidelines have changed. You could probably line them up and [note that] the changes are numerous. It’s hard to keep track of them.
For a while, we were doing tests to leave isolation. That means testing at 5 days, but some people would test a little later, such as at 10 days. It’s like in the hospital. If you do a blood culture when you’re ready to discharge somebody, and something shows up, you don’t know what to do. They don’t have a fever and they aren’t symptomatic, but you have to treat them now.
Following guidelines suggests that you don’t test at 10 days unless something new occurred, such as new symptoms or a new exposure, because these tests aren’t perfect. They may pick up on virus. For example, the PCR can pick up on virus that people are shedding when they aren’t contagious anymore because the full particles of the virus are gone. Now we’re just picking up fragments. We have to be careful to follow the guidelines. You’ll better understand what your tests mean. But if you start testing every day throughout the entire course, you may be thrown off by some of the results. That’s because of the inaccuracy of the tests themselves.
Mitchel Rothholz, RPh, MBA: Thanks, Jeff. One thing that a lot of folks ask questions about is the difference between an antigen test and an antibody test. Give a little insight for our audience. How do you respond to that question?
Jeff Goad, PharmD, MPH: Antigen tests are the PCR or point-of-care antigen test, in which you swab your nose at home. Those 2 are viral tests. They’re looking for the presence of the virus. In the world of laboratory results, an antibody test is called serology. We’re looking for the presence of antibodies. Antibodies tell you that you’ve been exposed to either the vaccine or the disease. It depends on the fraction of the antibody that you’re able to look at. But these antibody tests that people want to do just tell them whether they’ve been exposed.
When you look at where we are in the pandemic, perhaps antibody tests early on, especially in 2020 and in the beginning of 2021, were good proxies of what was happening in the population. Looking at a 5% sample of antibodies, you might be able to predict what percentage of the population has been exposed. But now we predict that well over 50% of the population has been exposed through either the vaccination or the disease itself. Antibody tests are of limited importance at this point. They’re the detective going backward to figure out whether you were exposed and developed antibodies. But they aren’t helpful in diagnosis or in treatment.
Transcript edited for clarity.
