Medical devices maker PolyNovo PNV.AX added 3.4% and ResMed RMD.AX climbed 2.4%. By Savyata Mishra July 19 (Reuters) - Australian shares closed lower on Monday, with losses seen across major sub-indexes, as a surge in Delta variant cases in the country and other Asian nations raised concerns about economic recovery. Australian authorities said Victoria state will extend a COVID-19 lockdown beyond Tuesday, while other Asian countries also struggled to curb the virus, denting markets already worried about global growth and high inflation.