According to scientists, having a common cold could protect people from contracting severe Covid-19.
One study suggests that the immune system’s reaction to different coronaviruses might be very similar to its reaction to the one behind the pandemic.
As a result, long-lasting immunity against those viruses, which are known to cause colds, can help the body fight Covid-19 if someone catches it, meaning it becomes less seriously ill.
German research also focuses on a less-discussed type of immunity, rather than the antibodies that have been at the forefront of many studies.
T-cell immunity appears to be more common among infected patients, and scientists say it could potentially last even longer.
Eight out of 10 people who have never had the disease have some degree of protection due to colds they have had in the past, according to the study.
And even Covid-19 patients with very mild symptoms developed a strong T-cell immune response, while they did not appear to have strong antibody responses.
It is still unclear whether people can contract the coronavirus twice, and this type of immunity may not prevent it, but it may lessen their symptoms if they do.
There are four types of coronaviruses known to cause the common cold and people
Researchers at Tübingen University Hospital in Germany studied the blood of 365 people, 180 of whom had had Covid-19 and 185 who had not.
When the researchers exposed people’s blood to SARS-CoV-2, the virus that causes Covid-19, people who had had the disease were already producing the strongest immune response.
But surprisingly, there was also an immune reaction in 81 percent of people (150) who had never had Covid-19.
This, the scientists said, was because they had already been infected with one or more of the common cold coronaviruses known to infect humans, called OC43, 229E, NL63, and HKU1, and as a result their immune systems cross-reacted. .
The researchers wrote: “The similarity to the human coronaviruses of the common cold provided a functional basis for … immunity in SARS-CoV-2 infection.”
The reaction the researchers were studying is caused by T cells, which are a type of white blood cell that produces long-lasting protection against serious infections.
But they are slower acting than antibodies and cannot stop a virus before it takes root.
A scientist who was not involved in the research, Professor Francois Balloux, an infectious disease expert who works at University College London, explained how they work today in a Twitter thread.
He said: ‘The T cell response is a delayed immune response and generally does not make the host refractory. [resistant] to infection …
However, T-cell immunity is essential to control an infection and reduce symptoms. SARS-CoV-2 appears to elicit a robust T-cell response even in mild / asymptomatic patients.
The findings from the Tübingen study raise hopes that people can develop natural immunity to Covid-19, which is something that antibody studies did not expect.
Antibodies are developed much faster by the body, a few days after infection, and fight disease before being stored in the immune system should it return.
The presence of strong antibodies can mean that people do not get sick with a virus a second time because the immune system is too fast to destroy it.
But many Covid-19 patients, especially those with only mild symptoms or none at all, did not appear to be developing detectable levels of antibodies, causing concern among scientists.
The Tübingen researchers wrote in their study: ‘Currently, the determination of immunity to SARS-CoV-2 is based on the detection of antibody responses against SARS-CoV-2.
‘However, despite the high sensitivity reported for several trials [tests] there is still a substantial percentage of patients with negative or borderline antibody responses, and therefore an unclear state of immunity after SARS-CoV-2 ‘infection.
They said their study found T-cell immune responses even in patients who tested negative for antibodies, meaning they had some level of protection.
The team said that T-cell immunity to Covid-19 deserved further scientific study and that they are now preparing to begin human trials of vaccines they hope can develop it.
The study was published on the Research Square website, not in a medical journal, and had not been reviewed by independent scientists prior to publication.
IMMUNITY TO OTHER TYPES OF CORONAVIRUSES CAN LAST ONLY SIX MONTHS
Covid-19 survivors can only be protected from reinfection for six months, according to a study that casts doubt on the possibility of lasting immunity.
Researchers at the University of Amsterdam followed 10 volunteers for 35 years and tested them every month for four weaker, seasonal coronaviruses, which generally cause mild illnesses similar to the common cold.
They found that those who had been infected with the strains, from the same family as SARS-CoV-2, the type that causes Covid-19, had “alarmingly short protective immunity.”
Antibody levels, substances stored by the immune system to allow the body to fight invaders in the future, decreased by 50 percent after half a year and completely disappeared after four years.
The researchers, led by Professor Arthur Edridge, a virologist at the University of Amsterdam, followed 10 volunteers from 1985 to this year.
Participants were tested every month for four seasonal coronaviruses, which were HCoV-NL63, HCoV-229E, HCoV-OC43, and HCoV-HKU1.
The time between infections (in months) is shown on the x-axis. The most common time a patient was reinfected was after 12 months.
But the researchers say that a more accurate way to measure immunity is by testing antibody levels. Their study found that the proteins that fight the virus fell by 50 percent after six months and by 75 percent after nine months.
There were a total of 132 coronavirus infections over the 35 years, and participants caught the viruses three to 22 times each.
The most frequent time between infections was one year, but there were three cases of reinfection at six months and two at nine months.
Most participants caught viruses during the winter, when there are much higher levels of virus circulating in populations.
The study found that patients lost 50 percent of their specific coronavirus antibodies after six months, 75 percent after one year, and 100 percent after four years.
Writing in the study, which has not yet been published in a scientific journal or reviewed by other scientists, the scientists said: ‘Seasonal coronaviruses are the most representative group of viruses from which the general characteristics of coronaviruses, particularly common denominators, can be concluded. like the dynamics of immunity. and susceptibility to reinfection.
In conclusion, seasonal human coronaviruses have little in common other than causing a common cold.
Still, they all seem to induce short-lived immunity with rapid antibody loss. This may well be a general denominator for human coronaviruses.
They added: “Our study also shows that herd immunity can be challenging due to the rapid loss of protective immunity.”
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