There are a few things to consider that I’ll add, which further bolster the idea that China has systematically covered up up a lab leak that caused the COVID-19 pandemic:
1. Coronaviruses are hard to contain, even if you have good practices. For example, the earlier SARS outbreak (from the early 2000s) had several documented lab leaks, including multiple within China (https://pmc.ncbi.nlm.nih.gov/articles/PMC7096887/).
2. The US state department was aware that China was conducting dangerous research on coronaviruses on poorly managed labs a few years before the COVID-19 pandemic (https://www.politico.com/news/magazine/2021/03/08/josh-rogin...).
3. The WHO got completely manipulated by China, either willingly or just due to their incompetence. For example, it is well documented now that the WHO publicly praised the Chinese government but privately was concerned and frustrated by the lack of transparency and sharing of vital information, including blocking visits to Wuhan (https://www.nbcnews.com/health/health-news/how-china-blocked...).
4. The NIAID (Fauci’s agency, under NIH) conducted gain of function research through a third party, EcoHealth Alliance. The grants are all public and document gain of function research, which was illegal since President Obama had banned it through an executive order. There was evidence that the NIH helped EcoHealth craft their grant language in a way to avoid oversight processes that would have blocked the grant (https://theintercept.com/2021/11/03/coronavirus-research-eco...). Note that the president of EcoHealth, Peter Daszak, is a listed author on gain of function publications from the Wuhan Institute of Virology. After years of trying to bury this, the Biden administration finally blocked funding to EcoHealth in 2024 (https://www.cnn.com/2024/05/16/health/us-government-suspends...).
5. China only allowed a WHO visit over a year after they knew of the COVID-19 outbreak, in early 2021. They only allowed specific people to participate in the investigation, and the only person allowed from the US, was the same Peter Daszak of EcoHealth Alliance who participated in the research at Wuhan Institute of Virology (https://www.cnn.com/2021/02/03/asia/wuhan-coronavirus-who-ba...).