While individuals can develop immunity after a natural COVID-19 infection, researchers still don’t know how long this immunity period lasts. Ultimately, how long this level of protection against the virus lingers depends on many factors like genetic health conditions, lifestyle, and diet.
Knowing how long immunity lasts can help discern how to interact with others safely. If you have recently received a COVID-19 vaccination, recovered from a natural infection, or both, this guide can help you. You will learn more about how natural immunity works, how long it lasts, and how to responsibly integrate into social settings.
How natural immunity works after COVID-19 develops
All individuals develop COVID immunity after infection, to an extent. A National Institutes of Health study claims that proteins and immune cells can identify and eliminate pathogens that reoccur, increasing protection against severe illness.
When you become infected with COVID-19, SARS-COV-2 enters the body by binding to angiotensin-converting enzyme-2 (ACE-2) receptors. From here, they penetrate the cell surface through a viral spike protein, spreading rapidly.
Then, antibodies and proteins in the body develop the ability to detect and neutralize foreign substances or viruses after infection. After identifying the pathogen, your body taps white blood cells (or memory cells) that can fight recurring infections in the future.
Helper and killer T-cells can also recognize and kill these pathogens. Finally, B cells generate new antibodies for protection.
After fighting off the virus, the immune system retains these neutralizing antibodies (Nab) as a form of disease control against future infections.
To measure immunity effectiveness, scientists study the presence of neutralizing antibodies. Current studies show that previously infected individuals have higher levels of Nab.
Evolving antibodies
There are three types of antibodies that help improve the immune response to SARS-COV-2:
- Macrophages: These cells attack viruses and bacteria, leaving behind antigens that antibodies learn to recognize in case of future infections.
- B-lymphocytes: Also known as B-cells, B-lymphocytes attack the antigens left behind by macrophages. Because these antibodies are unique to the particular virus that enters the body, B-cells can regenerate them as soon as they recognize that same virus in the future.
- T-lymphocytes: More commonly known as T-cells, T-lymphocytes destroy damaged cells and the infections within them. Once they eliminate the bacteria, T-cells often self-destruct. Any remaining T-cells become memory cells.
Just like SARS-COV-2 mutates and evolves, antibodies are no different. Over time, antibody titers become better at identifying and combating infectious diseases like COVID-19.
Below are a few ways that antibodies improve their immune responses:
- Antibodies become physically stickier to bind to the virus better. As they improve qualitatively, it takes fewer antibodies to neutralize a pathogen.
- Antibodies target different parts of the body. While changes are not immediate, individuals with the Omicron-specific vaccine get better at immune imprinting. Because mRNA vaccines generate the same antibodies against newer Omicron variants, the body experiences a decreased disease severity upon infection.
Active immunity
Active immunity indicates that the immune system has successfully produced antibodies to fight off SARS-COV-2 effectively. There are two types of active immunity:
- Natural immunity: The body produces and retains memory cells after developing a SARS-COV-2 infection. Depending on your physical health, it can take the body days to weeks to produce these antibodies.
- Vaccine-induced immunity: The body produces and retains antibodies after receiving a COVID-19 vaccine. These vaccines teach your immune system how to fight off infections without developing a serious disease. Your immune system is only considered “’fully protected’” only two weeks after you receive your final shot.
How Long will immunity last after getting COVID?
In the earlier days, experts believed immunity after getting COVID-19 lasted up to three months. However, later evidence has shown that this period lasts up to 11 months.
While many COVID-19 survivors have demonstrated all these post-infection components, there is not enough evidence to suggest how long this immunity lasts.
According to a Professor of Preventive Medicine and Infectious Diseases at Vanderbilt University, Dr. William Schaffner, Post-COVID immunity may mimic protection against common colds. Studies on the common cold indicate that immunity typically wanes after a year until reinfection.
How long your immune system stays protected also depends on the vaccine you receive. According to early research, individuals who received the Pfizer BioNTech vaccine or Moderna vaccine had immune protection for about four months. However, it’s still entirely possible to contract a breakthrough infection within that protection period.
Breakthrough infections occur when a fully vaccinated person still contracts a COVID-19 infection. While not common with the Delta variant, breakthroughs may occur with Omicron. You are more likely to experience breakthrough illness if you have a weakened immune system or happen to become exposed to a new, lesser- studied variant.
Fortunately, researchers found that T-cells respond best to the Omicron variant, even six months after vaccination. That said, the longest and best protection comes from hybrid immunity, which occurs after vaccination and natural infection.
Can you get a COVID-19 reinfection right after recovery?
Unfortunately, you can get a COVID-19 reinfection right after recovery, as infection with BA.4 and BA.5 doesn’t provide robust infection-induced immunity. A previous U.K. study showed that only 19% of fully vaccinated people with previous Omicron inflictions successfully evaded immediate reinfection.
How do you know you have already had COVID-19?
If you have never experienced symptoms or tested for COVID-19, there are a few ways to determine whether you have developed antibodies against the infection, including the following:
- T-cell receptor (TCR) assay: This test can determine whether you have had COVID-19 without symptoms through a blood or bone marrow sample. However, TCR assay accuracy tends to falter after vaccination.
- Nucleocapsid test: Unlike a TCR assay, a nucleocapsid test provides accurate results whether or not you are vaccinated. This test identifies the presence of antibodies created due to a SARS-COV-2 infection.
Note that these two tests cannot diagnose an existing COVID-19 infection and can only provide information about past infections.
Will subsequent infections be more or less severe?
Evidence shows that subsequent infections are often more severe. Research by clinical epidemiologists has demonstrated that people who become infected a second time are thrice as likely to undergo hospitalization and twice as likely to die.
In addition, the severity of the initial infection can dictate how severe a potential second infection will be. As per a study from November 2021 to March 2022, those hospitalized the first time were hospitalized again subsequently. By comparison, those who experienced a milder illness were able to avoid hospitalization after the first infection.
Overall, the individuals most likely to encounter severe to fatal consequences from future infections are the elderly, immunocompromised, and unvaccinated.
Omicron’s BA.4 and BA.5 subvariants evading immunity
As the BA.4 and BA.5 Omicron variants continue to dominate America., infections with previous viral variants are not as effective at providing immunity. A Harvard Medical School study showed that previous infection or vaccination did not effectively protect against new variants.
By comparison, those who became infected with the Omicron variant developed immunity with 80% effectivity against the BA.4 and BA.5 strains. Still, studies measuring antibody titers have reported that BA.5, BA.4, and BA.2.12.1 subvariants are not effectively neutralized by vaccine and infection-induced antibodies.
To complicate matters, the reinfection risk from the Omicron strain is triple that of any previous variant. Unlike the Beta and Delta variants, Omicron can substantially evade immunity.
How vaccine-induced immunity after receiving immunization works
There are four vaccines you can get for protection against COVID-19:
- Pfizer BioNTech
- Novavax
- Johnson and Johnson
- Moderna
These vaccines work by reinforcing the immune response to COVID-19. After vaccination, the body produces T-cells, B-cells, and neutralizing antibodies that fight against the virus. However, it may take time for your body to make these cells, so it’s entirely possible to develop COVID-19 during this period.
Generally, it takes about two weeks for the body’s immune response to kick in.
As per the Centers for Disease Control and Prevention (CDC), mRNA-based COVID-19 vaccines like Moderna (94% effectivity) and Pfizer (95% effectivity) remain the most effective against severe disease from new and old variants. By comparison, the Johnson and Johnson vaccine was only 66.3% effective against SARS-COV-2 in early trials.
Still, research shows that receiving any COVID-19 vaccine is better for developing a robust immune response than natural immunity. This is because vaccines are controlled and consistent, whereas immune responses to natural infections are far less predictable.
A need for booster shots
According to the CDC, a regular booster shot is recommended for everyone above the age of five. As such, individuals should receive a booster dose of Pfizer or Moderna at least five months after initial vaccinations. It is also recommended to receive a subsequent booster dose at least four months after the first shot. Individuals can opt to mix boosters.
While studies have shown that receiving a booster shot can improve immune response against COVID-19, vaccines tend to lose efficacy over time, particularly in older patients. In addition, the existing boosters are not effective in reducing illness severity for the new variants.
That said, experts from the Food and Drug AdministrationFDA and CDC are saying that a fourth vaccine dose is not necessary, as it will not provide adequate protection against serious illness from the Omicron strain.
Vaccination in kids
Though children are not as likely to develop severe disease due to COVID-19, it is not impossible. In fact, roughly 17,200 individuals below 20 have succumbed to a SARS-COV-2 infection. Children as young as six months can get vaccinated to improve natural immunity and T-cell response.
While Omicron remains the most threatening strain, older strains like Delta are not becoming more contagious in paediatric populations. Consider the following when getting your child vaccinated with a booster.
| Age | 1st Booster | 2nd Booster |
|---|---|---|
| 5-10 Years Old | 5 Month after initial dose, 3 Month after initial dose if immunocompromised | Not recommended |
| 12-17 Years Old | 4 Month after the first does if immunocompromised |
How hybrid immunity protects the most
Hybrid immunity occurs after vaccination and natural infection. With hybrid immunity, the body’s antibody levels increase drastically, providing better protection from old and new variants. Generally, hybrid immunity lasts for over a year.
With that in mind, you should not go out of your way to contract the disease for the sake of developing hybrid immunity. The virus is still unpredictable and can lead to severe consequences or even death.
Preventing COVID-19 reinfection
The SARS-COV-2 virus is ever-changing, so you never know when you might get the infection again. The good news is that there are many ways to prevent reinfection, including the following:
- Masking up: While masks are no longer required in most establishments, wearing one in high-risk situations or environments (e.g. crowded areas) can decrease the risk of transmission.
- Getting the COVID-19 bivalent vaccine: Updated vaccines can significantly boost your immune defenses. These vaccines are closer in biological makeup to the current circulating viruses, providing as much protection as possible.
- Getting tested regularly: Even if you are not demonstrating symptoms after a large gathering, getting a COVID-19 test makes you better safe than sorry. Testing will dictate how long you should remain in isolation, if necessary.
- Wash fresh groceries: Generally, fresh meats and vegetables carry a lot of germs that cause diseases. Decrease the risk of contracting illness by washing fresh groceries with antibacterial soap and water.
- Stay home if you are immunocompromised: Immunosuppressed patients have a higher risk of contracting COVID-19. If there is an outbreak in your area, avoid going out to crowded spaces.
Final thoughts
As SARS-COV-2 continues to evolve, so do our immune systems. But because the rate at which SARS-COV-2 mutates is so rapid, research and medicine are struggling to keep up. Thus, there is limited information regarding how long immunity after a COVID-19 infection lasts.
While some research suggests that immunity lasts for more than a year, this duration ultimately depends on the different variants and an individual’s unique physical conditions. The immunity provided by a fourth COVID-19 vaccine remains similarly unclear, but getting a booster can still adequately prevent infection.
For more information about Post-COVID and the immunity duration with your unique experience, reach out to us. Get to know our programs and courses that will alleviate your pain from long COVID and lead a new life.
