Studies show the activation of a different kind of T-cell called MAIT cell, which is an anti-bacterial cell but can also fight against certain viruses. These MAIT cells are seen to be strongly activated in the people who suffer from severe COVID-19, their number also seems to be declining indicating to the fact that they are involved in the fight against the virus. They are also seen to accumulate in the airways of the patient to a greater extent than a normal healthy person.