When did Omicron Covid variant arrive in UK and is it spreading?

Analysis: scientists are working full tilt to answer these vital questions that may give clues as to what is to come

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As new cases of Omicron continue to emerge in the UK, scientists are working full tilt to answer two vital questions: when did the variant arrive and is it spreading?

While at first glance those queries may seem less important than those around vaccine effectiveness or disease severity, the answers may give important clues as to what is to come.