RIO DE JANEIRO, BRAZIL – As some vaccines near the finish line in the race for an immunizer, it is still unclear how long the protection offered could last.
A crucial type of defensive blood cell persists for at least six months in people who have been cured of Covid-19, even for those who had no symptoms. This is indicated by a new study that may lessen the concern over immunity and its implications for a vaccine.
The study, conducted with 100 subjects, shows that all had T-cell responses against a range of coronavirus proteins, including the spike protein used as a marker in many vaccine studies, after half a year. Those with symptoms showed levels at least 50 percent higher than those with no symptoms.
As some vaccines near the finish line in the race for an immunizer, it is still unclear how long the protection offered would last. A low number of patients fell ill with Covid-19 twice.
“This is promising news,” said Fiona Watt, executive chairperson of the UK Medical Research Council. “If natural infection with the virus can trigger a robust T-cell response, then it could mean that a vaccine could do the same.”
An earlier study, published last month by Imperial College London, raised concerns that immunological defenses might decrease, as it showed that the percentage of Britons with antibodies decreased over time.
T-cells are not antibodies. They are white blood cells that can recall past diseases, kill virus-infected cells and awaken antibodies to command defenses when required. People infected with another coronavirus responsible for the SARS epidemic in 2003, for instance, still show a T-cell response to the disease 17 years later.
The study, conducted by a group of immunologists from 17 universities named Coronavirus Immunology Consortium in the United Kingdom, has not yet been peer reviewed. It may be the first to show that a robust immunological memory against the virus persists for this length of time, the authors said.
None of the patients whose blood and serum samples were studied had been hospitalized with Covid-19.
Source: InfoMoney