Many people hope that coronavirus immunity can bring them back to "normal life" and that those who recovered from coronavirus do not need to be concerned about being infected or infecting others.
Unfortunately, there are too many unknowns about immunity to novel coronavirus to be sure.
Learn what we currently know about coronavirus immunity, how coronavirus herd immunity could work and what antibody testing can tell you.
How Viruses Work
To understand coronavirus immunity, it is important to know how viruses work and how the immune system responds to them.
Viruses are pieces of genetic material surrounded by a protein coating. They can't reproduce without finding "host cells." This is why they seek out cells like the ones in our bodies.
When viruses enter our bodies, they find a cell and inject it with their genetic material. This allows them to take control of the cell and multiply.
To battle this, the body's immune system must destroy infected cells. When the body first encounters a new viral infection, it deploys T cells, which find and kill infected cells. If the infection continues, the body then deploys B cells, which create antibodies that can better attack infected cells.
Even after the infection has passed, antibodies remain in the body to help the body fight off future infection. How long these antibodies last in the body varies, ranging from days to a lifetime.
There are still many unknowns when it comes to coronavirus immunity. At this time, there is currently no way to know if novel coronavirus (SARS-CoV-2) induces immunity and how long any immunity could last.
Other types of coronaviruses, such as MERS, do induce immunity, often for several years. Many hope that SARS-CoV-2 will behave similarly.
Unfortunately, the data is not cut-and-dry. Most studies of immunity to coronaviruses, including SARS-CoV-2, focus on people who had severe disease and were hospitalized for their condition. There is significantly less data on the immune response in people who had mild symptoms or were asymptomatic.
On the other hand, scientists have not been able to confirm any cases of reinfection after novel coronavirus recovery. Some anecdotal evidence has emerged in multiple countries. However, it's possible that these patients falsely tested negative for the virus after their symptoms subsided and continued to harbor the virus.
All of these unknowns are why the Centers for Disease Control and Prevention and the World Health Organization currently state that there is no evidence to suggest novel coronavirus infection imparts immunity. More research needs to done.
Coronavirus Herd Immunity
As countries around the world relax quarantine measures, many wonder if herd immunity could help us reopen safely. Unfortunately, there are multiple reasons why we can't lean on herd immunity to help slow the spread of coronavirus.
What Is Herd Immunity?
Herd immunity is when most of a population is immune to an infectious disease, thus providing indirect protection to people who aren't immune to the disease.
Vaccines are the best tactic for creating herd immunity. Even if the majority of the population has had an infectious disease, if there is no vaccine, the disease can still be transmitted among children who haven't yet been exposed to the virus and people who are immunocompromised.
Obstacles to Coronavirus Herd Immunity
At this point in time, there are several reasons why herd immunity cannot help stem the pandemic in the United States. Instead, we must rely on other prevention measures.
Lack of Vaccine
While more research needs to be done on immunity to novel coronavirus, there is currently no evidence to suggest that herd immunity to coronavirus is possible without a vaccine. There is no vaccine for the novel coronavirus at this time, and we do not know when there will be one.
According to a report by the Center for Infectious Disease Research and Policy, current data suggests that around 70 percent of the population would need to be immune to achieve herd immunity to coronavirus.
More study needs to be done to determine current infection rates, but evidence suggests that infection rates are much lower. An antibody survey in New York, the hardest hit of the United States, reveals that only 13.9 percent of the population had been infected with coronavirus as of late April 2020.
Reaching the levels of infection needed to achieve herd immunity without a vaccine could be devastating, potentially overwhelming health care systems and leading to an extraordinary number of deaths.
Uncertainty of Immunity
Even more importantly, there is currently no evidence to suggest that people are immune after recovering from coronavirus. Even if novel coronavirus infection imparted immunity, that immunity could be short-lived and last only a few weeks or months. This would leave people vulnerable to reinfection later.
Coronavirus Antibody Tests
Coronavirus antibody tests identify specific antibodies in a person's blood that indicate they have been infected with the virus. Antibody tests are different than the tests used to detect an active coronavirus infection.
Antibody Tests and Coronavirus Immunity
Antibody tests do not tell you whether you are immune to coronavirus. They simply indicate if you have or haven't been infected with the virus. If you have been infected, it doesn't necessarily mean you are immune.
A positive antibody test isn't an "immunity passport." It does not mean that you can stop practicing the prevention measures that keep you and others safe, such as:
- Social distancing
- Washing your hands
- Avoiding touching your face
- Wearing a mask in public places
What a Coronavirus Antibody Test Can Tell You
If coronavirus antibody tests can't tell you if you're immune to the virus, then what can they do?
Antibody tests give you a better understanding of how you have personally been affected by the virus. It can also put you in a position to participate in plasma donation to help treat others.
Antibody tests are also being used to help determine how widespread coronavirus infection is in certain communities. This can be beneficial for creating public policy and better understanding how to keep communities safe.