Infected immune cells may explain severity of Covid, claims a report.

ISLAMABAD -- Twin studies have explained how infected immune cells prompt a massive inflammatory response leading to severe Covid-19, Nature reported.

While it has been known since the early days of the pandemic that inflammation leads to significant respiratory distress and other organ damage, scientists have struggled to pinpoint the triggers behind the inflammation. The studies - one published in Nature, and the other a preprint posted online and not peer-reviewed - implicate two types of white blood cells: macrophages in the lungs, and monocytes in the blood. These cells, once infected with the virus, trigger the inflammation.

The studies also reveal how the virus enters those cells, as well as confirm that the virus can infect and replicate in immune cells. The findings could offer a potential target for drug development. In the Nature paper, researchers from Boston Children's Hospital in the US examined blood samples from people with Covid-19.

They detected a type of cell death associated with inflammation, known as pyroptosis, in about 6 per cent of monocytes - 'early responder' immune cells that patrol the body for foreign invaders. The virus was probably activating inflammasomes - large molecules that trigger a cascade of inflammatory responses that ended in cell death, the team said

Another type of immune cell, macrophages in the lungs of...