Fact Check-Boston University hybrid COVID virus kills 80% of mice, not people

Original article from Reuters by Reuters Fact Check

Social media users have claimed that researchers at Boston University created a new strain of COVID-19 (Omi-S) that can kill 80% of people it infects. While the researchers said in a preprint study that they created a virus combining the spike protein of the Omicron variant with the backbone of an early, “ancestral” SARS-CoV-2 strain, the study was conducted in mice only, and cannot be generalized to humans, experts said.

The study authors explain in their preprint paper (here) that they set out to understand what causes the diminished disease severity seen with the Omicron variant as compared to past variants.

The authors describe the creation of a chimeric SARS-CoV-2 virus with the spike protein of Omicron and the remaining viral structures from the original virus strain that spread around the world in early 2020. The authors then infected different sets of transgenic mice designed to be susceptible to SARS-CoV-2 with one of the three strains: Omicron, the ancestral virus, or the Omi-S hybrid virus (here).

In the study, 100% of mice infected with the ancestral virus strain died, while 80% of those infected with Omi-S died, and none of the mice infected with Omicron died.

Click to read the full article in Reuters.