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Immune T Cells May Offer Lasting Protection Against COVID-19

Posted on by Dr. Francis Collins

Healthy human T Cell
Caption: Scanning electron micrograph of a human T lymphocyte (T cell) from a healthy donor’s immune system. Credit: National Institute of Allergy and Infectious Diseases/NIH

Much of the study on the immune response to SARS-CoV-2, the novel coronavirus that causes COVID-19, has focused on the production of antibodies. But, in fact, immune cells known as memory T cells also play an important role in the ability of our immune systems to protect us against many viral infections, including—it now appears—COVID-19.

An intriguing new study of these memory T cells suggests they might protect some people newly infected with SARS-CoV-2 by remembering past encounters with other human coronaviruses. This might potentially explain why some people seem to fend off the virus and may be less susceptible to becoming severely ill with COVID-19.

The findings, reported in the journal Nature, come from the lab of Antonio Bertoletti at the Duke-NUS Medical School in Singapore [1]. Bertoletti is an expert in viral infections, particularly hepatitis B. But, like so many researchers around the world, his team has shifted their focus recently to help fight the COVID-19 pandemic.

Bertoletti’s team recognized that many factors could help to explain how a single virus can cause respiratory, circulatory, and other symptoms that vary widely in their nature and severity—as we’ve witnessed in this pandemic. One of those potential factors is prior immunity to other, closely related viruses.

SARS-CoV-2 belongs to a large family of coronaviruses, six of which were previously known to infect humans. Four of them are responsible for the common cold. The other two are more dangerous: SARS-CoV-1, the virus responsible for the outbreak of Severe Acute Respiratory Syndrome (SARS), which ended in 2004; and MERS-CoV, the virus that causes Middle East Respiratory Syndrome (MERS), first identified in Saudi Arabia in 2012.

All six previously known coronaviruses spark production of both antibodies and memory T cells. In addition, studies of immunity to SARS-CoV-1 have shown that T cells stick around for many years longer than acquired antibodies. So, Bertoletti’s team set out to gain a better understanding of T cell immunity against the novel coronavirus.

The researchers gathered blood samples from 36 people who’d recently recovered from mild to severe COVID-19. They focused their attention on T cells (including CD4 helper and CD8 cytotoxic, both of which can function as memory T cells). They identified T cells that respond to the SARS-CoV-2 nucleocapsid, which is a structural protein inside the virus. They also detected T cell responses to two non-structural proteins that SARS-CoV-2 needs to make additional copies of its genome and spread. The team found that all those recently recovered from COVID-19 produced T cells that recognize multiple parts of SARS-CoV-2.

Next, they looked at blood samples from 23 people who’d survived SARS. Their studies showed that those individuals still had lasting memory T cells today, 17 years after the outbreak. Those memory T cells, acquired in response to SARS-CoV-1, also recognized parts of SARS-CoV-2.

Finally, Bertoletti’s team looked for such T cells in blood samples from 37 healthy individuals with no history of either COVID-19 or SARS. To their surprise, more than half had T cells that recognize one or more of the SARS-CoV-2 proteins under study here. It’s still not clear if this acquired immunity stems from previous infection with coronaviruses that cause the common cold or perhaps from exposure to other as-yet unknown coronaviruses.

What’s clear from this study is our past experiences with coronavirus infections may have something important to tell us about COVID-19. Bertoletti’s team and others are pursuing this intriguing lead to see where it will lead—not only in explaining our varied responses to the virus, but also in designing new treatments and optimized vaccines.


[1] SARS-CoV-2-specific T cell immunity in cases of COVID-19 and SARS, and uninfected controls. Le Bert N, Tan AT, Kunasegaran K, et al. Nature. 2020 July 15. [published online ahead of print]


Coronavirus (COVID-19) (NIH)

Overview of the Immune System (National Institute of Allergy and Infectious Diseases/NIAID)

Bertoletti Lab (Duke-NUS Medical School, Singapore)


  • John Hasty says:

    Thanks for the great article. It’s nice to see such important information being revealed from a group not supported by the National Institutes of Health.

  • Susan Gartner says:

    Very interesting article which may lead to a variety of vaccines.

    • Rick R says:

      This shows how a vaccine is less urgent and luckily may not be needed. Since this ties into what a top Immunologist said “look at the new data. Most of the people are actually immune already. So we do not have to protect the people, we have to protect the vulnerable people”- Immunologist Beda Stadler former Director University Institute of Immunology at the Insel Hospital in Bern Switzerland

      • Liz says:

        For those with compromised immune systems, such as lupus patients, a vaccine may be the only good option.

  • Joseph P says:

    So why would this not happen with HIV I just test positive I have no symptoms T-cell 1358 for 39 years. Why not the same repossessed

  • Robert C. says:

    About three years ago I developed ards which I was put on a ventilator for about seven days no one was for sure what I had I have been around three people who have had the corona virus and haven’t gotten any symptoms of the virus I need to get my T cells checked

  • D. says:

    That will be of great help for possible hopes regarding covid-19 control.

  • Naomi Bernstein says:

    After watching Chris Cuomo I learned about t cells and decided to find out more information related to this topic
    Very fascinating reading and learning more about what is being done in the world of the virus

  • Christopher Clausen says:

    One figure that would tell us a great deal both about how many people are immune and how easy or difficult it is to contract the virus is the number of spouses of covid patients who also get it. An early study from Wuhan indicated that only 27.8% did, but the sample was very small. Why don’t we ever see updates on this very revealing statistic, which should be easy to discover?

  • Viva says:

    Thanks for the very helpful sharing. This is a matter of primary concern. I love to learn carefully.

  • C. says:

    This is indeed the information needed in this moment. Thank you for your helpful sharing.

  • P Marcus says:

    This is encouraging data. We don’t have to buy into a warp speed-produced virus that would make us all human GMO’s and a few people even richer than they already are.

  • Muhammad Shafiq Ahmad says:

    Does T-cell for Tuberculosis help prevent Covid-19?

  • topwapi says:

    nice article.

  • iswinar says:

    The public is eagerly awaiting the Covid 19 vaccine. When will this vaccine be available?

  • champagnereef says:

    Please continue this great work, and I look forward to more of your awesome blog posts.

  • Viva says:

    this is a good article …

  • tbr says:

    Your information is useful and essential …

  • sg says:

    Your articles are very interesting, and I find some interesting information about social issues …

  • Cindy Birdwise says:

    Interesting T cell research.

  • Lisa W says:

    So those having T-cell lymphoma, would covid 19 affect them differently? Also, would it depend on the type of treatment they receive and how often?

  • swain says:

    Your information is very useful. Please continue this wonderful work. I thank you very much for sharing above

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