Are Some People Actually Immune to COVID?

There have been more than 100 million total cases of COVID-19 in the US and more than a million deaths, according to mid-April 2023 data from the Centers For Disease Control and Prevention (CDC). While these numbers are substantial, some people have still managed to escape the pandemic having never experienced a bout of COVID-19. In fact, research published in the CDC's December 2022 Morbidity and Mortality Weekly Report shows that in a survey sample of 1,574 participants, 44 percent of them said they never had COVID.

If you've experienced COVID-19 several times by now, then you may be wondering how the uninfected managed to avoid it. Were they more careful than the average person when it came to masking and spending time with others? Or are some people actually immune to COVID-19?

POPSUGAR chatted with infectious disease experts to find out why some people still haven't tested positive for COVID-19. Ultimately, there's no one reason, but a variety of factors that could help explain.

Possibly. "Given the degree of genetic variation in the human population, it would not be surprising if there is some subset that has very high resistance to COVID-19 infection," says Amesh Adalja, MD, an infectious disease physician and a senior scholar at the Johns Hopkins Center For Health Security. "There may be individuals that have certain genetic immunological features that make it very hard for them to contract the infection."

In fact, researchers have been asking the immunity question for a while now, and they've been seeking to study the genes of people who are genetically resistant to COVID infection since 2021. By studying their protective genes, the scientists hope it can get them closer to developing virus-blocking drugs.

The scientists aren't sure what kind of resistance mechanisms they'll find, though. One idea is that "some people don't have a functioning ACE2 receptor, which SARS-CoV-2 uses to enter cells," an article in the journal Nature states. Another thought is that "people resistant to SARS-CoV-2 might have very powerful immune responses, especially in the cells lining the insides of their noses." It's also likely that not just one but several factors play into resistance.

Until researchers can prove their theory about immunity, there are several other reasons someone may not have tested positive for COVID-19 yet, says Mohamad Assoum, PhD, an infectious disease epidemiologist at the University of Queensland.

When discussing why people haven't tested positive for COVID-19, it's important to know how people become infected. SARS-CoV-2 (the virus that causes COVID) is airborne, so most people become infected when they breathe in respiratory droplets that contain the virus or when those droplets land on their eyes, nose, or mouth. "The key avenues that an infected person can contaminate an environment directly around them, and increase the risk of transmission, is through coughing, sneezing, yelling, screaming, loud singing, etc. — basically anything that forces a large amount of exertion from the respiratory tract," Dr. Assoum explains.

We know that poorly ventilated high-traffic spaces that don't allow you to remain at least six feet away from other people increase the risk of transmission. We also know that mask-wearing, frequent handwashing, "safe sneezing" (i.e. coughing and sneezing into one's elbow), and avoiding touching one's face can decrease the risk of being infected with COVID-19. Of course, at some point in the past three years, most of us have had to go into public spaces to go grocery shopping, go back to in-person work, visit family members, and run essential errands. And while we can control some of our risk factors (like one-way masking), we can't control all of them. If you take public transportation to work, for instance, you can't guarantee that the vehicle you're on will be uncrowded or that your fellow passengers will be practicing COVID precautions.

Some people who never tested positive, however, simply may have been able to avoid being in high-risk environments more than others, either because they just got lucky or maybe they were able to work remotely or drive their own car rather than take public transportation. As a result, they may never have been exposed in a way that would lead to infection.

As many as 40.5 percent of COVID-19 cases are asymptomatic, according to research published in JAMA Network Open in December 2021. So it's possible that a sizable portion of the people who have never tested positive did have COVID at some point but simply didn't know it because they had no symptoms and never got tested during a time when they would have tested positive.

"A person who had an undetected very mild or asymptomatic infection will have some level of immunity against infection, especially if exposed to the same variant," Dr. Assoum points out. Meaning if you had an asymptomatic case of COVID-19 that you never tested positive for, then later were exposed to COVID-19, you might have enough immunity to avoid contracting the virus again. A recent study in The Lancet also found that immunity built up from infection drastically decreased the risk of hospitalization and death from COVID reinfection by 88 percent for at least 10 months. Still, experts suggest the strongest protection against getting COVID-19 is vaccination.

The importance of getting vaccinated and boosted cannot be overstated. While we know vaccination doesn't guarantee you won't get COVID, especially as new variants continue to develop, it does lower your risk of infection and can also help prevent serious illness and death, according to the CDC.

The available COVID-19 tests are very accurate, but they're not perfect. Some rapid at-home tests may be less sensitive to newer variants, per the Harvard T.H. Chan School of Public Health. Tests may not pick up very mild or asymptomatic cases, and they might come back negative if there's a lower viral load in the body. That's why if you're symptomatic and you received a negative result on a rapid at-home test, Dr. Assoum suggests getting a PCR test as well. If that's also negative, it's possible that your symptoms are due to a different infection or allergies, not COVID. But it's also possible that a low viral load or an improperly taken sample may have led to a false negative PCR.

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There's no guarantee that you won't ever get infected, especially with new variants developing. But if you're hoping to keep up your streak, then taking safety precautions, including getting vaccinated and boosted, wearing a mask during large indoor settings, and practicing safe hand hygiene, can be crucial. You should also continue getting tested if you have any symptoms or after being exposed, in accordance with CDC guidelines.

POPSUGAR aims to give you the most accurate and up-to-date information about the coronavirus, but details and recommendations about this pandemic may have changed since publication. For the latest information on COVID-19, please see resources from the WHO, the CDC, and local public health departments.