US researchers have developed a new lethal Covid strain in a laboratory – echoing the type of experiments many fear started the pandemic.

The mutant variant — which is a hybrid of Omicron and the original Wuhan virus — killed 80 percent of mice infected with it at Boston University.

When a similar group of rodents were exposed to the standard Omicron strain, however, they all survived and only experienced 'mild' symptoms.

The scientists also infected human cells with the hybrid variant and found it was five times more infectious than Omicron.

This suggests the man-made virus might be the most contagious form yet.

It will no doubt surprise many Americans that such experiments continue to go on in the US despite concerns similar studies may have led to the global Covid outbreak.

Russian President Vladimir Putin on Wednesday announced a partial mobilization in Russia as the war in Ukraine reaches nearly seven months.

Putin’s address to the nation comes a day after Russian-controlled regions in eastern and southern Ukraine announced plans to hold votes on becoming integral parts of Russia. The Kremlin-backed efforts to swallow up four regions could set the stage for Moscow to escalate the war following Ukrainian successes on the battlefield.

The referendums, which have been expected to take since the first months of the war, will start Friday in the Luhansk, Kherson and partly Russian-controlled Zaporizhzhia and Donetsk regions.

US President Joe Biden said the coronavirus pandemic is over. He spoke about this in an interview with CBS television.

The head of state announced the end of the COVID-19 pandemic and noted that the United States continues to work on this problem.

“The pandemic is over. We still have a problem with COVID, we are still working on it a lot ... (But) if you notice, no one is wearing masks, everyone seems to be in good shape, ” he stressed.