Researchers at Boston University say they have developed a new COVID strain that has an 80% kill rate following a series of similar experiments first thought to have started the global pandemic that began in China. 

The variant, a combination of Omicron and the original virus in Wuhan, killed 80% of the mice infected with it, the university said. When mice were only exposed to Omicron, they experienced mild symptoms.

The research was conducted by a team of scientists from Florida and Boston at the school's National Emerging Infectious Diseases Laboratories. 

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They extracted the spike protein from Omicron and attached it with the strain first detected at the onset of the pandemic that began in Wuhan, China. They then documented how the mice reacted to the hybrid strain. 

"In…mice, while Omicron causes mild, non-fatal infection, the Omicron S-carrying virus inflicts severe disease with a mortality rate of 80 percent," they wrote in a research paper. 

The new strain has five times more infectious virus particles than the Omicron variant, researchers said.

Fox News has reached out to the university. 

COVID-19 was first detected to have come from a wet market in Wuhan, though many believe the virus was engineered at the Wuhan Institute of Virology. The World Health Organization continues to face criticism for its handling of the crisis in its early, most pivotal, days.

The Omicron variant is highly transmissible, even in those who are fully vaccinated. The spike protein is responsible for rates of infectivity, according to researchers, other changes to the virus’ structure determine its deadliness.

One limitation to the study was the breed of mice used, as other types are more similar to humans.