WHO actually went to Wuhan in Feb and Jul last yr for investigations and hence it is the third time the team is in Wuhan now. Singapore was involved for the Feb investigation, see WHO report : https://www.who.int/…/who-china-joint-mission-on-covid…
Hence it is not true WHO only investigates Wuhan one year later with the evidence no longer in existence.
The current trip is significant as the scientists have more knowledge of covid-19 a year later and also covid-19 has been discovered in other parts of Europe even before Dec 2019, thus lending credence to the notion that Wuhan may not be the source of the outbreak.
Hence during today’s press briefing, the WHO team concurred that there is evidence that Covid may have emerged outside of Wuhan. So it is imperative that they must go to places outside China which had reported covid-19 before Dec 2019 to do the tracing.
Covid-19 first emerged in China because the Chinese healthcare system mandates the doctors to input pneumonia cases into a computer system to track the possible recurrence of SARS. So the above-average no. of pneumonia cases in Wuhan in Dec 2019 triggered an alert to the Chinese healthcare authority for investigation and hence we came to know that covid-19 first emerged there. But if one looks at US pneumonia records in the winter 2019, it was reported there was a higher than usual no. of deaths due to pneumonia then. But the Americans thought that they were just flu-related pneumonia and so they did not take action like what the Chinese did.
Hence in a nutshell, some time during the winter of 2019, covid-19 virus managed to spread globally but China discovered it first because it had been ready to act for the possible recurrence of SARS which mirrored the symptoms of covid-19.
On the question why the European countries did not have the outbreak like Wuhan did before Dec 2019, one possible reason could be Wuhan is densely populated and also the Chinese lifestyle of socialising means that many people were exposed to it for a long period in the winter and so R0 was higher compared to European cities which discovered traces of covid-19 before Dec 2019. But we came to know that Italy had an outbreak of covid-19 cases in Feb 2020 which showed that R0 would build up over time as long as people were unaware of this silent pandemic.