UF Health Shands chief epidemiologist says vaccines essential to tamp down COVID-19 delta variant

The nation is in the midst of the latest coronavirus surge, with the highly contagious delta variant fueling a record number of hospitalizations in Florida. The drumbeat of daily news about the pandemic can be anxiety-inducing.

University of Florida Health infectious disease specialists, however, note that one message should stand out like a beacon amid the deluge of information about the coronavirus — COVID-19 vaccinations are safe and highly effective, even against delta.

Nicole M. Iovine, M.D., Ph.D., chief epidemiology officer for the University of Florida Health Shands hospital system, discusses key points about the coronavirus so people can better understand what they’re seeing in the news or on the internet.

Question: Some people still have concerns about getting a COVID-19 vaccination. What should they know?

Answer: There’s a lot of misinformation out there on social media and some websites. The two mRNA vaccines that we offer here at UF Health, the Pfizer and the Moderna vaccines, have excellent safety profiles. In fact, more than 177 million people have been vaccinated and the rate of serious adverse events with the mRNA vaccines is extremely low — less than 0.001%. Compare that with the rate of serious adverse events, including death, with COVID-19 infection, which is at least 10,000 times more. In addition, they cannot affect one’s fertility because mRNA can’t interact with DNA. Pregnant women can receive both of these vaccines safely. So the safest thing that you can do is to get your COVID-19 vaccine.

Q: Why have we seen the emergence of different coronavirus variants?

A: Getting vaccinated is more important now than ever because of the delta variant of COVID-19. Like all living things, the virus that causes COVID-19 mutates constantly. This happens primarily in unvaccinated people and in people who are severely immunocompromised because without any preexisting immunity, the virus replicates unchecked in the body for days or even weeks. The longer the virus is present, the greater the chance a mutant will emerge. This delta variant has mutated such that it has the ability to transmit much more easily than prior variants of COVID-19. This is driven by the extraordinarily high viral loads that infected people carry. We have clearly seen this in our own infected health care workers and patients in the past month. The viral levels that we’re seeing now are the highest we've ever seen throughout this pandemic.

Q: But aren’t fully vaccinated people still being infected by the coronavirus?

A: Yes. But that doesn’t mean that the vaccine doesn’t work because the overwhelming majority of vaccinated people are either asymptomatic, or if they contract COVID-19, they’re just mildly ill and do not develop severe enough illness to be admitted to the hospital. In fact, about 95% of all hospitalized patients with COVID-19 are unvaccinated, and more than 99% of patients who die from COVID-19 are unvaccinated. It is the rare individual who is vaccinated yet becomes sick enough to be admitted. And nearly all of these patients are severely immunocompromised from cancer treatment or are organ transplant recipients. These patients cannot mount an effective immune response to vaccination and so are at risk for severe illness. That’s just one more reason to get vaccinated — to help protect people who are immunocompromised.

Q: Why would a fully vaccinated person still get COVID-19?

A: It’s really a numbers game. If there’s more virus than there are antibodies to combat it, COVID-19 infection will occur. The good news is that in a vaccinated person, the immune system will quickly ramp up production of antibodies and clear the virus. In an unvaccinated person, this can’t happen quickly so the virus levels continue to rise and they stay infected longer. That makes it more likely that they will become severely ill. The good news is that in a fully vaccinated person, the immune system recognizes the threat and ramps up antibody production very quickly to clear the virus and that’s why vaccinated people don’t become severely ill. We’ve seen this play out in the viral loads of vaccinated people. The levels may start out high, but they decline very rapidly. This is in stark contrast to unvaccinated people in whom the virus stays at high levels for a longer time, making it more likely that they will get ill. The best way to protect yourself and those around you from getting seriously ill with COVID-19 is to get vaccinated.

Q: Do people who have previously been infected with the coronavirus still need to get vaccinated?

A: Even if you’ve recovered from COVID-19 infection, you still need to get vaccinated. Here’s why: When you have natural infection, your body will make antibodies against all parts of the virus. That sounds like a really good thing, but actually, only a small fraction of those antibodies will protect you from getting reinfected. When you get a COVID-19 vaccine, your body will make a focused and strong immune response against just the spike protein of the virus and we know that antibodies against the spike protein are what is needed to protect you from getting sick with COVID-19.

Media contact: Ken Garcia at kdgarcia@ufl.edu or 352-265-9408.