Scientists in America created a new strain of engineered Covid with an 80% kill rate after splicing part of one of the newest Omicron mutations onto samples of some of the earliest Covid strains found in the USA at the start of the pandemic. When the new virus strain was tested on mice in a lab, eight out of 10 died.
Mice exposed to just the Omicron strain fell ill, but none died. Mice who were exposed to the original strain, from Washington State, all died. Researchers at Boston University are trying to find out whether part of the protein of the Omicron variant explains why it usually causes less severe disease.
The researchers say the new strain was actually less lethal to the mice than the original virus - the one they spliced Omicron proteins onto.
