The results show that almost all survivors have immune cells to fight re-infection.
Survivors of COVID-19 may have immune defenses against severe infection from the SARS-CoV-2 virus for months, or even years after infection, a study suggests.
The findings, based on analyzes of blood samples from 188 COVID-19 patients, suggest that almost all survivors of the disease have the immune cells to fight against relapse. disease.
“Our data suggest that the immune response is there – and it remains,” Professor Alessandro Sette from the La Jolla Institute of Immunology in the US.
The researchers measured antibodies, B memory cells, helper T cells and killer T cells – the four components of immune memory – at the same time.
The study, published in the journal Science, helps to clarify some data regarding data from other institutions, which showed a significant reduction in COVID-fighting antibodies in the months after infection.
Some feared that this depletion of antibodies meant that the body would not be equipped to protect itself from relapse.
Sette explained that a decline in antibodies is quite normal.
“Of course, the immune response decreases over time to some degree, but that’s normal,” he said.
“That’s what immune responses do. Their first stage is ramping up, and after that miraculous extension, the immune response finally makes a bit of a contraction and gets to a steady state,” said Sette.
The researchers found that specific viral antibodies persist in the bloodstream months after infection.
They said the body has immune cells called ready-made B memory cells, saying that if a person comes across SARS-CoV-2 again, those cells could reactivate and make antibodies to fight it. re-infection.
The SARS-CoV-2 virus uses its “spike” protein to initiate human cell infection, so the researchers looked for B memory cells that were specific for the SARS-CoV-2 spike.
They found that spike-specific B memory cells increased in the blood six months after infection.
“COVID-19 survivors also had a ready-made force of T cells to fight relapse. CD4 +” helper “T memory cells entered, ready to stimulate an immune response if they saw SARS- CoV-2 again, “the researchers said.
Many CB8 + “killer” T memory cells also stayed, ready to destroy infected cells and stop re-transplanting, they said.
“The different components of the immune system work together, so seeing COVID-fighting antibodies, B memory cells, CD4 + T memory cells and CD8 + T memory cells in the blood is more than eight months later disease is a good sign, “said LJI Professor Shane Crotty.
“This means that people would have a good chance of being immune, at least against serious disease, for that period of time, and possibly much longer,” Crotty said.
However, the researchers cautioned that the immune system varies greatly from person to person.
They saw a 100-fold range in the amount of waterproof memory.
“People with weak immune memory may have a recurrent case of COVID-19 in the future, or they may be more likely to infect others,” the researchers said.