People get sick, especially in autumn. And they infect each other. Reporting that some people working at the lab were sick, without any knowledge about kind of sickness is only going to add fuel to the conspiracy theories.
I suspect I had COVID-19 in the US late December 2019, but as of yet, the CDC doesn't acknowledge that possibility, and I've had enough exposure since that time that there's no reasonable way to test the hypothesis.
At a certain point, some of the investigations stop being practical to investigate further.
IIRC, public toilets due to fecal matter were a possible infection vector (I hope I am using the term correctly) [4], which suggests that there had been covid cases since December in Italy as the traces were in waste water [2,3].
Some hypothesise that covid had been circulating in humans long before the market outbreak [5], this hypothesis does seem to corroborate the hypothesis that the virus had long spread before the first 'official' outbreak in Wuhan.
[1] https://www.rfi.fr/en/france/20210311-surprises-about-french...
[2] https://www.independent.co.uk/news/world/europe/coronavirus-...
[3] https://www.bbc.com/news/world-europe-53106444
[4] https://www.forbes.com/sites/jamiegold/2020/06/18/new-scient...
[5] https://www.cbc.ca/radio/quirks/mar-27-covid-pandemic-origin...