Here’s Some Hope: People Have Lasting Immunity To COVID-19, Even After Mild Cases
After six months of the COVID-19 pandemic, a body of scientific work is emerging that shows our immune system is capable of remembering COVID-19 and producing a lasting immunity.
Over the course of the pandemic, medical fears have been shaped as much by what the future holds in terms of second waves and mutations during the cold of winter, as by what has been happening in the world at any particular moment.
However, studies both peer-reviewed and not, are seeing positive changes in the human innate immune response to COVID-19 that suggest the diseases’ days of unfettered infection are numbered.
For example, in one peer reviewed study from Nature, immunologists in Singapore studied the cellular memory of T-cells, an important immune cell that weaponizes other immune responses in addition to tracking and eliminating pathogens on their own.
The researchers found that:
- People with or recovering from COVID-19 displayed immediate memory T-cell activation to the virus’ proteins.
- People with an infection history—going back as far as 17 years—of SARS-CoV-1 which emerged in China around 2002-2003, had long-lasting memory T-cell responses that ”displayed robust cross-reactivity to the N protein of SARS-CoV-2.”
- And, perhaps most interesting, SARS-CoV-2-specific memory T-cell activation was found “in individuals with no history of SARS, COVID-19 or contact with individuals who had SARS and/or COVID-19.”
The last point is certainly enough to give us hope. And yet more positive research emerges.
Another study, this one not yet peer-reviewed, found that the response of antibodies—one of the primary classes of immune cells used to defend against pathogens—stayed active in saliva up to 115 days after the onset of symptoms in COVID-19 patients.
While antibody and T-cell responses in the blood have been extensively studied, this work, published in the preprint publication, has been one of the first to look at responses in mucus cells. The scientists note this is an important area of research since the virus infects in the upper respiratory tract.
“The immune response is doing exactly what we would expect it to,” Gommerman, an immunologist at the University of Toronto who worked on the study, told CNN. “At least at about four months, which is, as far as, most of us can measure at this point in the pandemic.”
Work on yet another kind of immune cell, the ‘helper’ T-cell as opposed to the ‘killer’ T-cell, was completed earlier in the year when several studies published in Nature and Science found that the helpers could also, more than half the time, identify COVID-19 and sound the alarm, and that these helpers were present in patients that had never been exposed to COVID-19.
The evidence of re-infection is, at this point, non-existent, which suggests humanity’s collective immune system is working well to combat it.
“So that is all good news,” Gommerman said. ”That means that people who are infected with this novel coronavirus should have the capacity to mount what’s called a memory immune response to protect themselves against infection.”