SCMP science reporter Holly Chik reports on mainland China opening its borders after three years, as the Omicron surge continues to wreak havoc. HKU epidemiologist Prof Ben Cowling contrasts the Hong Kong experience and forecasts how this surge will play out over the Lunar New Year holiday; Thomas Yau reports from Shanghai on the healthcare crisis; Xinlu Liang reports on the new black market in Paxlovid-style drugs and renewed misinformation on Chinese social media about treatments and the XBB…