A New study found that patients who previously had colds caused by viruses related to Covid-19 could have immunity to the disease.
According to the latest study led by immunologist Professor Antonio Bertoletti and colleagues from Duke-NUS Medical School in Singapore, patients who previously had colds caused by viruses related to Covid-19, known as betacoronaviruses, could have immunity or may suffer a milder form of the disease.
Betacoronaviruses, specifically OC43 and HKU1, are said to be causing common colds but also severe chest infections in the oldest and youngest patients. They share many genetic features with the coronaviruses: Covid-19, MERS and SARS, all which passed from animals to humans.
Coronaviruses are thought to account for up to 30 percent of all colds, but it is not known specifically how many are caused by the betacoronavirus types. Now scientists have found evidence that some immunity may be present for many years due to the body’s ‘memory’ T-cells from attacks by previous viruses with a similar genetic make-up, even among people who have had no known exposure to Covid-19 or SARS.
T-cells are a type of white blood cell and form part of the immune system’s second line of defence to any viral attack, kicking in around a week after infection.
They have long been thought to offer lasting protection to viruses and as such are dubbed ‘memory’ cells. The latest study offers some ‘remarkable’ findings on the potential role of T-cells in fighting Covid-19.
The protective effect of these cells against Covid-19 needs to be proved in further trials, but experts say patients who recovered from the deadly lung virus, SARS in 2003, show immune responses to key proteins found in Covid-19.
The researchers said: “These findings demonstrate that virus-specific memory T-cells induced by betacoronavirus infection are long-lasting, which supports the notion that Covid-19 patients would develop long-term T-cell immunity.
Our findings also raise the intriguing possibility that infection with related viruses can also protect from or modify the pathology caused by SARS-Cov-2 [the strain of coronavirus that causes Covid-19].”
Blood was taken from 24 patients who had recovered from Covid-19, 23 who had become ill from SARS and 18 who had never been exposed to either SARS or Covid-19.
Surprisingly, according to the scientists, half of patients in the group with no exposure to either Covid-19 or SARS possessed T-cells which showed immune response to the animal betacoronaviruses, Covid-19 and SARS.
This suggested that the patients’ immunity developed after exposure to common colds caused by betacoronavirus or possibly from other as yet unknown pathogens.