What is COVID-19 natural immunity?

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Natural immunity happens when someone contracts a pathogen, such as a virus. Their body then produces antibodies to protect them and fight the pathogen.

Antibodies are proteins that recognize and attach to viruses. This marks them for destruction by other parts of the immune system.

Some antibodies remain in the immune system after attacking and destroying the pathogen. Because of this, if a person encounters the same pathogen again, the immune system remembers its first exposure. It can quickly reactivate the appropriate antibodies to neutralize the pathogen.

While natural immunity can be effective, it is not always lifelong. The protection antibodies offer can gradually decline over time, meaning a person’s immunity can “wear off.”

Sometimes, a person can encounter a new strain of a virus that is different from the one they had. Their immune system may not recognize the new strain, so their natural immunity may not protect them from infection.

Cell-mediated immunity also plays an important role. In this type of immunity, the body’s T cells activate when they encounter a pathogen. After fighting an antigen, such as the SARS-CoV-2 virus, the cells remember their immune response. This means they are well-equipped to fight off the same pathogen in the future.

Vaccines help a person’s body develop immunity to a disease.

Some vaccines contain an inactive or weakened form of a virus. This tricks the body into thinking it has contracted the infection and causes the immune system to produce antibodies and defenses against the pathogen. If a person later comes into contact with the real pathogen, their immune system is primed and ready to fight it off.

The most common type of COVID-19 vaccine is an mRNA vaccine. This teaches the body’s cells to build the spike protein of the SARS-CoV-2 virus. If the body encounters the virus in the future, this protein triggers the body’s immune response.

The immunity that someone gains from vaccination is usually long lasting and may continue throughout their lifetime. However, like in the case of COVID-19, individuals may need booster doses.

Vaccination is typically more reliable than natural immunity.

Each vaccination uses the same formula and dosage, and the person has an identifiable date of vaccination. As a result, healthcare professionals understand how immunity gradually declines over time after vaccination.

In contrast, there is more variability in how people develop natural immunity. When a virus triggers an infection in someone, it is challenging to know which strain it is, their viral load during the infection, or when the infection occurred. Natural immunity also has the downside of causing illness — vaccines provide immunity without infection.

Although COVID-19 vaccination is the more reliable option, it may not result in lasting immunity. People may need multiple doses and boosters as scientists adapt vaccines to newer variants.

Yes. Everyone who is able should receive COVID-19 vaccinations, regardless of whether or not they have had the virus. There are very few medical reasons not to get the vaccine.

The Centers for Disease Control and Prevention (CDC) recommend that everyone aged 6 months and older receive the vaccine and booster shots.

Although people can still contract SARS-CoV-2 after being vaccinated, the infection is usually milder and carries a reduced risk of side effects. Vaccination also provides stronger protection than natural immunity.

A 2021 study of people hospitalized with COVID-19 found that unvaccinated people who had a previous infection were more than twice as likely to contract the infection than those who were fully vaccinated. Therefore, the vaccine is the best way to protect people from a SARS-CoV-2 infection and more contagious variants.

According to a 2022 study, naturally-induced COVID-19 immunity protects against reinfection by a pre-Omicron variant for at least 16 months. However, this protection dwindles over time.

Natural immunity does reduce the likelihood of developing severe COVID-19 symptoms, but the study’s authors say this is not a reason to skip vaccination.

In another 2022 study, researchers recruited participants with both natural and vaccine immunity. They found that these individuals had more protection against the virus than those who did not. This is called hybrid immunity.

While it seems that prior infections and natural immunity can offer some protection against variants, experts still emphasize the importance of vaccination. As SARS-CoV-2 variants continue to emerge, people should be fully vaccinated and have the required boosters to ensure the best possible protection against new strains.

Natural immunity occurs when a person contracts a pathogen and their body develops antibodies and other defenses. Vaccine-induced immunity is similar, but instead of a natural infection, a person has exposure to a weakened or inactive version of the pathogen.

Although a SARS-CoV-2 infection triggers natural immunity, vaccination is the best way to ensure immunity against COVID-19 and its variants. It also reduces the likelihood of serious illness and hospitalizations.