I had an appointment with a substitute doctor this week. Attesting to his renown, his office walls were crowded with yearly awards demonstrating his leadership in his field.
He is a hematologist/oncologist. I was there to receive one of the twice-yearly injections I receive for osteoporosis. The same medication is given in greater strength and frequency to cancer patients to prevent bone fractures.
As he leaned forward to give me the injection, his mask was comfortably positioned beneath his nose.
I was distressed by his apparent carelessness: the man deals with cancer patients all day long, for goodness sake.
I was also amused, as it reminded me of a cartoon I’d seen, which I hope does not offend. I think it makes an important point in a memorable way.
Two roughly drawn panels—black outline, white interior. Inside the left panel is a sketch of a man with a long thin face and long thin nose. His mask is comfortably positioned beneath his nose. The legend reads: “Wearing your mask like this…”
The right panel features a full-length sketch of the same man. That legend reads: “…is like wearing your underwear like this.”
But this was serious business, so I asked the doctor about his mask.
“I had COVID in March,” he told me. “I lost weight and slept a lot, and on the 14th day, I got up and could have run a marathon.”
He added that his wife, daughters, and one daughter’s boyfriend had also had mild cases and fully recovered. “And,” he said with certainty, “I’ll never get it again.”
I questioned him about the antibodies, which my reading had suggested was far from a settled matter. In fact, there are more than 100 vaccines in the works that are based on antibodies. But some people who recover never have antibodies, and others have them only briefly.
“It’s not the antibodies,” he responded. “It’s the T cells. They carry memory of the virus and prevent it from reinfecting.”
He said he was so sure he’s safe that he often greets his elderly neighbor with a hug, unworried that he might infect her.
Huh! Or more specifically, Huh?
I had heard the T-cell theory, so I did a little research. In fact, there’s some exciting emerging research based on T cells and the coronavirus. Little had been known til recently about the role of the T cells in SARS-CoV-2, the virus that causes COVID-19.
For much of the following, I’m relying on Derek Lowe, who writes about drug discovery and pharma for In the Pipeline, an “editorially independent blog from the publishers of Science Translational Medicine.”
In May, Lowe wrote:
“One of the big (and so far unanswered) questions about the coronavirus epidemic is what kind of immunity people have after becoming infected. This is important for the idea of ‘re-infection’ (is it even possible?) and of course for vaccine development.”
I’ll spare you Lowe’s careful explanation of the various and complex aspects of our immune systems; if you’re interested, you can read it via the above link.
Instead, we’ll focus on two primary types of T cells. One is CD8+ T cells (among other names), which kill the virus-infected cells “before they can break open and spread more viral particles,” writes Lowe.
“And then there’s another crowd, the CD4+ T cells, also known as T-helper cells and by other names…The helper T cells have a list of immune functions as long as your leg, interacting with many other cell types.”
Those immune functions include spurring the CD8+ cells and “activating B cells to start producing specific antibodies,” among other tasks.
Lowe describes what I think of as the “Goldilocks response” to COVID-19:
“What you want: a robust response that clears the virus, remembers what happened for later, and doesn’t go on to attack the body’s own tissues in the process.”
This was what a team from La Jolla Institute for Immunology in California and Mt. Sinai in New York was studying. Comparing infected patients who’d recovered with those who hadn’t been exposed to the virus, they found all the exposed patients had CD4+ cells that responded to three specific proteins: Spike, M, and N.
Lowe suggested that this discovery made the prospect of a vaccine more likely, and that though most efforts have been focused on Spike, adding the other proteins to the mix might further strengthen a vaccine’s efficacy.
Another study suggested that the memory T cells may protect some people with COVID-19 because they “remember” previous encounters with other human coronaviruses.
Of the large family of coronaviruses, six of them have been found in humans. Four are responsible for the common cold. The other two are more dangerous; they caused SARS (SARS-CoV-1) and MERS (MERS-CoV). ( I assume that means SARS-CoV-2 is number seven.)
Here’s the cool part: in that second study, reported in Nature, Antonio Bertoletti of the Duke NUS Medical School in Singapore and his team looked at blood samples from people who’d recently recovered from mild to severe COVID-19. They all produced T cells that recognized many parts of the SARS-CoV-2 virus.
Then they looked at blood samples from people who’d also survived SARS 17 years ago—and their memory T cells from that illness also recognized parts of SARS-CoV-1.
Apparently, their immune systems were still attuned to protecting against the disease 17 years later.
After that, they checked for these T cells in blood samples from healthy people who’d had neither SARS nor COVID-19—and more than half had T cells that recognize one or more of the proteins under study.
So it’s possible that there are people who have some immunity to COVID-19 based on their previous bouts with the common cold.
“This makes one think, as many have been wondering, that T-cell driven immunity is perhaps the way to reconcile the apparent paradox between (1) antibody responses that seem to be dropping week by week in convalescent patients but (2) few (if any) reliable reports of actual re-infection. That would be good news indeed.”
Francis Collins, MD, who heads the National Institutes of Health, writes cautiously in the NIH Director’s Blog:
“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.”
These studies may have huge implications in helping us combat COVID-19.
Bottom line for me: When I see that doctor again for my injection in 6 months, though I hope he’s wearing his mask properly, I won’t be quite as worried as I was this time. The degree of his certitude may not yet be warranted, but at least his decision is based on some solid emerging research.