VAAL TRIANGLE - The National Institute for Communicable Diseases says masks, social distancing and the lockdown have kept the traditional winter flu from spreading. According to the NICD, flu cases usually start to rise sharply around mid-to-late April, but as of end-May there was still little sign of it. The NICD says while cases of two flu strains were detected in the Western Cape, there has been no influenza circulating from all other provinces. They say there's an even more marked delay in the onset of seasonal RSV, another common pathogen that causes flu-like symptoms, and which can be fatal in young children. South Africa’s RSV season usually starts at the end of February, but by end-May it, too, was nowhere in sight.