How Long Does COVID-19 Immunity Last?

How Long Does COVID-19 Immunity Last?
Natalie Stein

Exercise, Fitness & Nutrition Expert | Lark Health

Your Lark coaching program is always available to guide you with physical and mental health. So when our experts were compiling the latest research on COVID-19 immunity, they said we should share it with you too.

When COVID-19 started dominating daily life and putting health, livelihoods, and the economy at risk, discussions about immunity began. Would someone who caught the virus and recovered from it be immune from catching it again? If so, how long does COVID-19 immunity last? 

How Antibodies Work in Immunity

Antibodies are part of the immune system. When immune cells recognize a foreign body, they can produce antibodies that are specific to that antigen and that can lock onto it. Antigens can be bacteria or viruses, such as the novel coronavirus that causes COVID-19. 

Some of these specific antibodies can last long after the disease or other exposure (such as a vaccine) occurs. That is one reason why vaccines for diseases such as measles are so effective: the vaccine can be effective for years or life.

Importance of COVID-19 Immunity and Herd Immunity

Herd immunity occurs when a high proportion of people within a community are immune to an infectious disease. When only a few people are immune, the bacteria or virus has many opportunities to infect others and continue to spread. When enough people are immune, the bacteria or virus has trouble finding new people to infect. Eventually, the disease gets stamped out or is manageable, such as in the case of tuberculosis, in which the rare cases that are still found are isolated from others so transmission does not occur.

An early theory during the COVID-19 pandemic was that if enough people in the community got and recovered from COVID-19, the community would develop herd immunity. The estimate for COVID-19 seems to be between 50 to 80% of the population being immune. In addition, the people who recover from COVID-19 need to be resistant to getting sick again, and that is where questions arise. How long do patients maintain immunity after recovering from COVID-19?

How Long Does COVID-19 Immunity Last?

Like so much else about this new disease, we do not know how long COVID-19 immunity lasts. A recent study published by researchers at the University of California, Los Angeles, reported that antibody levels dropped significantly in participants by 2.5 months post-infection [1]. That study included only 34 patients. A study among nearly 20,000 patients in a system in New York concluded that antibody levels stayed high for at least 3 months [2].

A long-term study out of the Netherlands looked at four seasonal coronaviruses, or viruses that are related to the novel coronavirus that causes COVID-19 [3]. Researchers tracked people for 35 years and looked at their coronavirus infections and antibody levels. Participants commonly got sick again within 12 months, implying that immunity did not last that long. Antibody levels appeared to stay high for at least 6 months.

A Vaccine and COVID-19 Immunity

It seems as though the whole world is waiting for a COVID-19 vaccine so we can finally go back to stores, concerts, friends’ houses, and school without worrying about getting sick. However, will a vaccine still work if naturally-induced COVID-19 immunity does not last forever?

On the surface, the outlook seems bleak if antibodies, or the cells that prevent the virus from invading, do not last for long after a person recovers from COVID-19. However, there are some bright spots. First, vaccines can induce stronger immune responses than getting the disease naturally, so it is possible that a COVID-19 can induce longer-lasting immunity. 

Second, immunity may not be all about the antibodies. A different kind of immune cell, called memory B cells, may remember how to make the antibodies. That means they may recognize the virus and make antibodies upon exposure even if there were no antibodies present before.

The COVID-19 pandemic has turned life upside-down, and billions of people are hoping for a solution, and soon. While we do not know how long COVID-19 immunity lasts, researchers are constantly learning more about it and are doing their best to come up with a vaccine that will make our world safer again.