Can you get COVID more than once?

More than 48 million Americans have been infected with COVID-19 since the pandemic began in 2020. As time passes and immunity begins to wane, many Americans are wondering if they can get it. COVID-19 more than once, also known as COVID re-infection.

To help answer these questions, we explain the differences between natural immunity and vaccine-induced immunity, why you should still get vaccinated even if you’ve had COVID before, and shed more light on cases of re-infection and breakthrough.

How do viruses infect cells?

To date, COVID-19 has taught Americans how deadly viruses can be. While it’s easy to focus on the end result – serious illness, hospitalizations, and death – there are many steps that must occur for an infection to occur.

Viruses, like the coronavirus, are made up of a genetic code (either DNA or RNA) protected by a protein coating. Viruses cannot replicate themselves. In other words, they need a host to cause infection. The host is usually an animal or human, in which the virus finds cells and injects them with their genetic material. The virus then makes copies of these cells which cause damage to your body.

As viruses replicate, the immune system triggers a response. Your body contains lymphocytes, a type of white blood cell that defends itself against bacteria, viruses, parasites and fungi. These lymphocytes mainly come in the form of B cells and T cells. First, T cells destroy the body’s own cells that have been infected with the virus. Then the B cells take over to produce antibodies that also attack the virus.

Once the infection is over, there are antibodies left to fight against a future infection. How long these antibodies remain present is what researchers have studied since the inception of COVID-19.

COVID reinfection rate

Reinfection occurs when you become infected, recover from the virus, and then become infected at a later date.

Although there have been cases of COVID-19 reinfection, they remain rare, according to the Centers for Disease Control and Prevention. Last summer alone, reinfection cases accounted for less than 1% of total COVID-19 cases, according to a study by the University of Missouri School of Medicine. An examination of over 9,000 Americans showed a reinfection rate of 0.7%, with an average time to reinfection of 3.5 months after a first positive test.

However, the accuracy of these figures is somewhat uncertain. For starters, it can be difficult to keep track of reinfection rates because many cases of COVID-19 are mild and people may never know they have it again. In addition, some cases of reinfection may be mistaken for traces of the virus remaining in the body and triggering further testing. For example, the coronavirus can shed the virus for several months. This does not mean that a new infection has occurred, but rather that the original infection has not yet left your body.

The reality is that no immunity or vaccine is ever 100% effective, so there are bound to be people who contract COVID-19 for the second time. As Americans experience increased fatigue from COVID, reinfection rates are likely to rise due to waning immunity and lax safety measures such as wearing masks and social distancing .

So far, this is the case in Oklahoma. The state health department no longer produces weekly updates on reinfection rates or breakthrough cases, but September figures showed the reinfection rate (1,093.8 per 100,000 cases) was twice as high as breakthrough cases (557.4 per 100,000 cases). In just two months, the reinfection rate doubled from 512.8 last August to 1,093.8 in September.

What is a COVID breakthrough case?

You may have heard or seen the word COVID breakthrough case recently. This new term is used to describe reinfection in people who have been vaccinated. Yes, vaccines prevent infection for most people, but there is always a small chance that you could still get infected, hence the name breakthrough.

The chances of experiencing a breakthrough case after being vaccinated are low, according to data from last year. A study of 4 million fully vaccinated people determined that there was a 1 in 5,000 chance of a breakthrough infection. Other studies are closer to 1 in 100, or 1 percent.

Inevitably, these numbers will vary depending on the state and region where COVID cases are higher than other regions. In New York City, where COVID was a hotbed of cases in 2020, there have been more than 175,000 confirmed breakthrough cases, representing 1.4% of people aged 12 and over who are fully vaccinated. Likewise, in Virginia, the infection rate from January 2021 to November 2021 was 1.15% for people who were fully vaccinated.

The goal of vaccines is not necessarily to outright prevent COVID infections. Rather, it is about reducing the severity of infections and limiting hospitalizations and deaths. With breakthrough infections, people who are fully vaccinated tend to have less severe symptoms of shorter duration.

It’s important to remember that breakthroughs, even if they are less severe, are still contagious. You can be asymptomatic and carry the virus without realizing it, allowing unvaccinated people to become infected. This is why washing your hands and wearing a mask in public remain two essential steps in reducing the transmission of COVID-19.

COVID immunity after infection

Immunity, from a general perspective, is a state in which your body remembers pathogens and foreign invaders (in this case the coronavirus) to be better prepared in the event of reinfection.

Initially, the antibodies were expected to last about three to four months, according to a National Institutes of Health study in late 2020. Others believed the number to be between 90 and 180 days.

Either way, the term immunity is subjective as it can vary from person to person. One person may have months of immunity, while another may have more than a year of immunity. New variants of the coronavirus may also play a role. Viruses can mutate and become resistant to some aspects of vaccines, reducing the duration and effectiveness of your immunity.

Immunity to some other coronaviruses, like the one that caused Middle East Respiratory Syndrome (MERS), has been shown to last for years. Immunity to COVID-19 is less clear, mainly due to ongoing research – researchers tend to study people with moderate to severe COVID symptoms. However, this information does not apply to the majority of Americans since most cases are mild or remain asymptomatic.

As experts continue to analyze the longevity of COVID immunity, a study conducted by the Yale School of Public Health found that immunity to COVID-19 was short – a 50% risk of reinfection after 17 months. The study was an estimate using a previous analysis of related viruses such as SARS-CoV, MERS-CoV, and several other coronaviruses that cause the common cold.

An additional study found that a previous COVID infection reduced your risk of re-infection by 80% for six months. However, that number was only 47 percent for adults 65 and older.

Should I get the COVID vaccine if I had COVID?

Yes, the immunity only lasts that long. It is best to protect yourself and others by getting vaccinated. This is because the immunity induced by the vaccine is considered to be superior to natural immunity.

Natural immunity vs vaccine

Natural immunity has become a popular topic lately, but the truth is that this type of immunity varies with the person and the type of pathogen. For example, people infected with measles are unlikely to contract it again due to a strong antibody reaction that creates long-lasting immunity.

As more and more research is conducted, it is believed that natural immunity to COVID-19 weakens and is not as strong as immunity to the vaccine. The more time passes, the more likely it is that the genetic material of the coronavirus will be able to overcome the host’s immunity and lead to reinfection.

There is also data that shows a relationship with not being vaccinated and higher rates of reinfection. The CDC released a study last summer that found that unvaccinated people were 2.34 times more likely to be re-infected, meaning that receiving the vaccine lowers your risk of contracting COVID-19 a second time.

An additional study found that unvaccinated people who previously had COVID were 5.49 times more likely to be hospitalized due to reinfection than people who had been vaccinated for COVID without a history of infection.

If anything, a previous COVID infection, when combined with a full dose of vaccine, allows longer lasting antibody levels, according to a large study by Johns Hopkins. In a study of over 1,900 people, antibody levels increased over time after two doses of the vaccine – 14% at one month, 19% at three months, and 56% at six months. It’s even more of a reason why you shouldn’t skip your second COVID vaccine.

The COVID-19 vaccine contains messenger RNA (mRNA) that triggers a target immune system response. Once injected, mRNA teaches the immune system how to create antibodies that protect against COVID.

To learn more about COVID-19, visit our COVID-19 Resource Page. Learn more about COVID-19 vaccines here, Where make a vaccination appointment by visiting the Oklahoma State Department of Health website.