Can you become immune to COVID-19?
Medically reviewed by Leigh Ann Anderson, PharmD Last updated on Apr 14, 2020.
Official Answerby Drugs.com
- Researchers are actively investigating if antibodies will protect against reinfection with COVID-19 disease, but still do not know how well -- or for how long -- they will work.
- Length of immunity can be estimated by looking at other coronaviruses, but because the SARS-CoV-2 is a new coronavirus, these numbers are not proven.
- Science and research around immunity should inform policy decisions about how and when to ease social distancing guidelines.
If there is any one good thing about catching the novel coronavirus known as SARS-CoV-2, it’s that you may have built an immunity to the virus to help prevent further COVID-19 disease.
But how long can your coronavirus immunity last? Will it be a lifelong protection, as with measles or chickenpox, or just short-lived, as with the influenza vaccine?
How robust will your immune response be to a future coronavirus infection if you’ve had only mild symptoms -- or no symptoms at all?
How do you become immune to COVID-19?
About 460,000 people have recovered from COVID-19 out of 1.91 million infections to date, as reported by Johns Hopkins University Coronavirus Research Center. Overall, about 80% of people will recover from the virus without serious symptoms.
Antibodies are proteins that recognize viruses, bacteria and other foreign substances in your blood. They are produced in response to an infection and help to prevent reinfection -- or lessen severity of infection -- from the same illness. Your immune system uses an advanced network to recognize a virus you’ve had before, and releases antibodies to fight it off again.
Antibodies can differ in how well they work:
- For example, some illnesses like measles or chickenpox, are fought off for a lifetime because your immune system memory always recognizes the virus to keep it at bay.
- Other viruses, like seasonal influenza, can change from season to season, so a new flu vaccine is needed each year.
- Immunity to certain viruses, such as the common cold, is very short-lived -- possibly only a few months -- or maybe even non-existent.
However, how well those antibodies will remember the coronavirus and fight off another COVID-19 infection is not yet well-defined. Researchers say we need “neutralizing antibodies” that can prevent infection by binding to the portion of virus that allows it to enter the host cell. This site is most likely on the spike protein the SARS-CoV-2 virus.
Do other coronaviruses lead to immunity?
To develop answers, scientists are looking at clues from the past.
The common cold is an example of a coronavirus where immunity is short. Colds tend to recur, and we keep fighting them off. In an experiment with coronaviruses that lead to the common cold, researchers infected volunteers to see if a rechallenge -- reinfecting with the same virus a year or so later -- would lead to symptoms.
- Antibodies do seem to appear with the coronavirus that causes a cold, but their levels decline over time.
- In one study, volunteers who had been infected did develop immunity and appeared to be protected from the coronavirus illness after a rechallenge 12 months later.
- In another study after rechallenge, volunteers developed less severe symptoms and lower virus levels, especially in those who had exhibited a strong immune response initially.
Patients who recovered from the 2002 SARS-CoV, a coronavirus closely related to the current SARS-CoV-2, appear to have antibody protection for about two years. How strong this immune defense is against reinfection is not known.
For the Middle East Respiratory Syndrome coronavirus (MERS-CoV), a more serious viral respiratory disease from 2012, there were only about 2500 cases over eight years. The mortality rate of MERS was about 35%, but survivors did generate an immune response detected for up to two years.
It is not yet known whether similar immune protection will be observed for patients with SARS-CoV-2.
Will I have immunity to coronavirus if I recover from an infection?
On Monday April 13, World Health Organization (WHO) officials stated that not all people who recover from the coronavirus have the needed antibodies to fight a second infection. This raises concerns that recovered patients may not have enough immunity -- or any immunity at all -- to coronavirus
Marc Lipstich, from the Dept. of Epidemiology, Immunology and Infectious Diseases at Harvard’s T.H. Chan School of Public Health wrote that these uncertainties “will become clear when more serologic surveys, or blood tests for antibodies, are conducted on large numbers of people.” The accuracy of the antibody tests will be important to determine these numbers.
Lipstick takes an “educated guess” that most COVID-19 patients will have an immune response, “some better than others.” It may offer protection over the medium term -- “at least a year” -- he states, but then effectiveness of the circulating antibodies could decline. Theoretically, patients with more severe disease who mount a more robust immune response may be better protected. Asymptomatic patients may have lower amounts of measurable antibodies, or maybe none at all.
Is there an antibody test for COVID-19?
Antibody tests will help to quantify the number of cases of COVID-19, including those that may be asymptomatic or have recovered.
In the US, only one antibody test from Cellex Inc. is FDA-approved through an Emergency Use Authorization, although many other tests have been developed. A simple finger prick of blood gives a result in 15 minutes. A positive result means, yes, you have antibodies to the coronavirus, whether you have experienced symptoms or not. How protective these antibodies are is not yet known.
Initially, health care workers, first responders, and other essential employees may be the first to receive an antibody test. How antibody test results should be used to reintroduce everyone back into society is an ongoing and an important debate that scientists and policy experts should prioritize.
Can you catch coronavirus twice?
According to WHO, it is not yet known if people can get reinfected with SARS-CoV-2, the virus that causes COVID-19. This is an important question to answer and is under investigation.
A recent report from South Korea’s Centers for Disease Control and Prevention stated that 91 people in that country had retested as positive for COVID-19 after having been previously classified as cleared of the virus.
Scientists seem to think the cases from South Korea may have been reactivations, not brand new reinfections, or that patients may have had a false negative test in the middle of an ongoing infection. Faulty antibody tests and false positive results are also a possibility.
If I am immune to COVID-19, can I go back to work?
The World Health Organization (WHO) has stated that lowering levels of social distancing and reopening society -- going back to work, school, and other public spaces -- must occur slowly. You should generally follow the directions of your local or national public health authorities.
At the April 13th WHO press update, Tedros Adhanom, Director General of WHO, outlined six measures that countries should take before they consider lifting social distancing measures:
- Transmission of the virus should be controlled.
- A health surveillance system should be in place to detect, isolate and treat patients. Significant capacity for contract tracing should be in place.
- Health system, hospital and nursing home outbreaks should be minimized.
- School, workplaces and other essential locations should have preventive measures in place.
- The risk of importing the disease from abroad should be under control.
- The community should be fully educated, engaged and empowered to adjust to the new norm of COVID-19 restrictions and requirements.
Patients who recover from COVID-19 do appear to make antibodies to the virus. Research is ongoing to determine how well these antibodies protect people from reinfection, and for how long.
People may have differing levels of immunity based on how robust their response was to their COVID-19 infection.
As the world discusses how to relax social distancing restrictions, scientists and public health policy experts must determine how antibody tests should be used to help control infection rates and allow society to safely “reopen”.
Immunity through an effective and safe vaccine will be the best mode to control the spread of SARS-CoV-2. Researchers say it could be 18 months or longer until a vaccine is available.
- Lipstick M. Who is Immune to Coronavirus? The New York Times. April 13, 2020. https://www.nytimes.com/2020/04/13/opinion/coronavirus-immunity.html
- World Health Organization (WHO). WHO Director-General's opening remarks at the media briefing on COVID-19. 13 April 2020. https://www.who.int/dg/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing-on-covid-19--13-april-2020
- Greely H. Covid-19 ‘immunity certificates’: practical and ethical conundrums. STAT. April 10, 2020 https://www.statnews.com/2020/04/10/immunity-certificates-covid-19-practical-ethical-conundrums/
- Li R, Pei S, Chen B, et al. Substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (SARS-CoV2). Science. 2020 Mar 16. 2020.
- McKenna S. Scientific American. What Immunity to COVID-19 really means. April 10, 2020. https://www.scientificamerican.com/article/what-immunity-to-covid-19-really-means/
- Greenfieldboyce N. Do you get immunity after recovering from a case of coronavirus? NPR. March 20, 2020. https://www.npr.org/sections/goatsandsoda/2020/03/20/819038431/do-you-get-immunity-after-recovering-from-a-case-of-coronavirus
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