The scientific journal Nature has published a detailed report on the sightings of Asian Hornets in the UK from 2016 to 2019 and the follow-up investigations.
You can read it here: https://www.nature.com/articles/s41598-020-76690-2.pdf
October 2020: Giant Hornets found in Washington State, USA
Please note: the hornets found were vespa mandarinia, not the Asian Hornet, vespa velutina.
Details of all confirmed sightings of Asian Hornets in the UK are available on this UK Government web page: https://www.gov.uk/government/publications/asian-hornet-uk-sightings