A team of scientists dispatched by the World Health Organization to investigate the origins of the COVID-19 outbreak in Wuhan will arrive in China on Thursday, the country’s National Health Commission said Monday—more than a year since the outbreak began.

The announcement comes days after WHO Director-General Tedros Adhanom Ghebreyesus said he was “very disappointed” with apparent delays in approving the visit, which has been under development since last summer. The team was supposed to begin investigations in the first week of January, but China reportedly failed to approve their visas.

“In order to ensure the smooth progress of the work of the international expert group in China, necessary procedures need to be fulfilled and relevant specific arrangements need to be made. At present, the two sides are still in discussions,” China Foreign Ministry spokesperson Hua Chunying said at a press conference when asked about Tedros’s comments last week.

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The forthcoming probe is the second investigation led by the WHO into the start of the COVID-19 pandemic in China. The WHO sent scientists to China to investigate the Wuhan outbreak in February last year, however Beijing hamstrung their work.

At first, Beijing denied the group access to Wuhan, which was still under lockdown. Eventually, the government permitted a small team to visit the city, but prevented them from visiting hospitals or the seafood market where the outbreak was suspected to have originated.

The failure of the first investigative team to fully probe the Wuhan outbreak prompted members of the WHO governing body, the World Health Assembly, to issue a resolution calling for a new, international investigation in May of last year. The resolution passed, setting the scene for the investigation starting Thursday.

Beijing has opposed the resolution, dishing out retribution against Australia for its role in spearheading the movement. Beijing imposed new tariffs and blockades on Australian imports shortly after the resolution passed, even though the scope of the investigation is much smaller than what Canberra had hoped for.

The WHO mission is tasked with investigating the animal origins of the coronavirus, as well as the role of the wet market in precipitating the early outbreak. The team will also comb through hospital records to identify any potential cases of COVID-19 that occurred earlier than Nov. 17, 2019—the earliest COVID-19 patient identified by China.

Beijing has long pushed against the narrative that COVID-19 “originated” in China, asserting instead that Wuhan was just the first place to identify the new virus. State media present the upcoming probe in China as part of a global investigation into the virus’s origins and often flag reports that suggest COVID-19 emerged in Europe earlier than initially thought.

Meanwhile, a fringe theory that continues to circulate through China suggests the virus was imported into Wuhan along with frozen food from another country.