A recent batch of studies, many early stage and not yet peer reviewed, show that humans have a “robust” immune response to Covid-19 that can protect them from further infection, even if they had mild symptoms. How long that protection will last is not yet clear, but studies indicate it could take months.
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PERTH, AUSTRALIA – APRIL 20: Registered nurse Heather Hoppe receives flu vaccination at the trial clinic at Sir Charles Gairdner Hospital on April 20, 2020 in Perth, Australia. Healthcare workers in Western Australia are taking part in a new trial to test whether an existing vaccine against tuberculosis can help contract their chances of getting COVID-19. 2000 frontline staff from Fiona Stanley, Sir Charles Gairdner and Perth Children’s Hospital are taking part in the research trial, in which half of the participants will see the existing Bacillus Calmette-Guérin (BCG) vaccine next to their flu vaccine, while the other half receive the regular flu shot. The BCG vaccine was originally developed to work against tuberculosis, but it is hoped that it can help reduce the chance of shrinking coronavirus, as well as reduce the severity of symptoms and increase long-term immunity. The BRACE trial is led by the Murdoch Children’s Research Institute. (Photo by Paul Kane / Getty Images)
One leading immunologist says the findings give optimism that humans do not have to maintain recurrent coronavirus infections. It also provides evidence that a vaccine can protect people for longer than a short period of time.
“The hope I had was to realize with these early studies,” said Dr. Ian Lipkin, director of the Center for Infection and Immunity at Columbia University Mailman School of Public Health.
Beginning in the pandemic, some scientists questioned how long the body would remember the infection and continue to produce antibodies – the proteins that the body makes to fight an infection – to protect it. Studies have shown that these antibodies decrease over time and different people produce different numbers of antibodies. It is unclear what kind and what level of an antibody reaction is needed to provide protection.
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“This is an accumulation of more information that will make people more comfortable with the idea that we will have immunity that will last longer,” Lipkin told CNN. “We do not know that for a fact, but there are a few things that are interesting that gave me a basis for optimism.”
One of the studies showed that T cells seem to be activated by this new coronavirus. T cells are important immune cells that stimulate different arms of the immune system and that also attack and kill cells that have already been infected by a virus.
Another study that looked at donor blood samples found that a large portion of the population, between 20% and 50% of people in some areas of the US, may have T cells that recognize the new coronavirus, even if this person has never been infected. It is still unclear why people have them. It may be called cross-protection from other coronaviruses that cause the cold. What scientists do not yet know is if this provides protection against Covid-19, but it has potential.
“So, this is very good news and it’s optimistic,” Lipkin said. “You know, it’s a little blue sky we were looking for.”
Jennifer Gommerman, who worked on one of the early studies, found that the anti-anti-response to this novel coronavirus is “actually quite durable.”
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“The immune response is doing exactly what we would expect,” Gommerman, an immunologist at the University of Toronto, told CNN. “At least in about four months, that is, for sure, most of us can measure up to the pandemic at this point,” Gommerman said.
Gommerman said there is some decline in the level of antibodies, as one would expect in a normal immune response, but it does not fall short.
Gommerman said another study from the work of immunologist Marion Pepper at the University of Washington found that the immune response is not a “one-trick pony.” Instead, it is like a “Swiss Army clipper who has many different tools” for fighting the novel coronavirus.
Pepper’s study shows that some of the T cells form memory T cells that can surround and provide protection in case a person encounters the new coronavirus again. Studies looking at SARS, another coronavirus, have shown that the response to T-cell memory is long-lived.
Gommerman said because scientists have not seen a record of re-infection, even with not as widespread as the pandemic, which strongly suggests that the body’s immune system is working well against this threat, and re-infection is less likely.
“That’s all good news,” Gommerman said. “This means that people infected with this new coronavirus must have the capacity to attach what is called an immune response to memory to protect themselves from infection.”
What remains unclear is how long the human body’s response to the new coronavirus can provide protection. Since it is only seven months after the pandemic, these studies cannot determine how long protection lasts, but at least one shows that even a mild infection has provided protection for three months and suggests that protection is likely to last longer.
“The hard part about sustainability is that it’s a time-dependent measurement,” said David Masopust, a Howard Hughes Medical Institute scientist in the Department of Microbiology and Immunology at the University of Minnesota. “We want to know what that looks like five years from now. Unfortunately, we can not predict that today,” Masopust added. The research results are what scientists would expect from a coronavirus, he said.
“What the research shows us is encouraging – that things look normal in the sense that you have what we call humoral immunity, as antibodies,” Masopust told CNN.
“And you’re developing B cells, which can differentiate into cells that make antibodies, and it looks like you have T cells that look durable, to the extent that this study was able to do that. view, “he added. “It would be bad or sad news if they got anything other than these studies.”
Masopust said while these studies are stimulating, it is not yet clear whether the memory of the immune system can actually protect people against infection. “Again, this is a real world experiment that, unfortunately, will be done by people coming into contact with the coronavirus,” Masopust said.
Gommerman said the findings about this robust immune response mean that all future vaccines should also provide protection for a useful period of time.
“This lasting immunity we see means that if we come up with a vaccine that is well-designed and safe, a vaccine can replicate what the virus does,” Gommerman said. “People have to take it when it comes.”
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HOUSTON, TX – JULY 28: (EDITORIAL USE ONLY) Medical staff members treat a patient in the COVID-19 intensive care unit at United Memorial Medical Center on July 28, 2020 in Houston, Texas. COVID-19 cases and hospital appearances have reopened since Texas, pushing intensive care units to full capacity and raising concerns about an increase in deaths as the virus spreads. (Photo by Go Nakamura / Getty Images)
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Thomas Hansler, 54, receives a COVID-19 vaccination from Yaquelin De La Cruz at the American Research Center in Hollywood, Florida on August 13, 2020. (Photo by CHANDAN KHANNA / AFP) (Photo by CHANDAN KHANNA / AFP via Getty Images)
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