While researchers around the world in some 20 countries are racing to find a vaccine for Covid-19, some scientists say the more we learn about this coronavirus, the more perilous our road may be to find a safe exit route.
Generally speaking, the expectation is that either we’ll fight off the virus and generate immunity, or researchers will develop a vaccine that will provide immunity.
But that may not be the way things play out, according to a report from the CBC.
According to McMaster University immunologist Dawn Bowdish, research on how our immune system responds to other coronaviruses suggests that a vaccine or exposure to the virus may not provide the kind of lifelong immunity we get with the chickenpox vaccine.
“What we expect based on what we’ve learned from other related viruses like SARS and MERS is that the immune response will likely fade,” she said.
The durability of immunity is critical to understand when it’s safe for recovered individuals to go back to work, especially if they’re on the front lines, the CBC report said. It’s also going to be essential for vaccine research to understand how long they might be protected.
But there are paradoxes appearing as researchers seek to understand more about how to respond to this coronavirus. For one thing Bowdish said the strength of immune response in patients who died from Covid-19 looks very similar to the response in those who lived, the CBC report said.
“They had the same levels of antibodies, which are one feature that generally gets rid of a virus, but they also have one major difference in their immune response,” she cautioned.
Scientists studying autopsy samples from people who died from Covid-19 found that an important set of immune cells is active — but possibly in the wrong place. These are T cells which are part of the adaptive immune system that can learn to recognize and attack viruses with great precision, the CBC report said.
“It looks — to all the world — that those cells are ending up in the lungs and helping clog the air exchange in the lungs,” said Bowdish.
“If these T cells get inappropriately activated, they sort of lose their precision and so there is a lot of collateral damage. And that looks like it might be part of the problem in this infection,” added Bowdish.
For years, the focus of most vaccine development was to elicit antibodies that could neutralize viral pathogens by binding to them and preventing them from infecting our cells, the CBC report said.
That strategy has worked with many viruses. Tetanus might be a good example as Bowdish expects that vaccine may provide the same type of immunity that we may see with the Covid-coronavirus.
With the Tetanus vaccine, “the antibodies do exactly what they’re supposed to do — they bind, they stop the toxin from making us sick.”
But at the moment, we still don’t know enough about the specific antibody response to the Covid-19 virus to know how well they stick to the virus to prevent them from entering our cells, nor how well they do their job of clearing the virus, the CBC report said.
Bowdish is hoping she and other scientists can find a “magic bullet” antibody that will prevent the virus from infecting our cells.