SA Federation of Trade Unions (Saftu) leader Zwelinzima Vavi says he will test for Covid-19 for the third time after his second test results came back positive.

Vavi was discharged from hospital two weeks ago after testing positive for the coronavirus.

Last Thursday, he shared on Twitter that he and his youngest son were getting tested for the second time, saying: "If we test positive still it would only mean that the virus has taken longer to die."

On Tuesday, Vavi told Jacaranda FM that he was still positive for Covid-19 after testing for a second time but was no longer showing any symptoms of the virus.

He said his son, who tested positive last month, was now negative.

He added that his wife, who initially was negative, was now positive and will test again when they go together.

"I drank lots of water and rested for hours. I also [took] lots of vitamin C and iron and have had a lot of garlic - never had to munch garlic in the manner I have been doing in the past few days and weeks.

"Yet on the 14th day I went back, and I was still positive and it was sort of a little setback, but I was forewarned that it was possible and that the virus might refuse to go away and that I might need to go back if that happens, and I'll go on Friday."

Eating garlic and ginger have not been listed as preventive measures against contracting the virus. Antibiotics also do not work against the virus.

According to the World Health Organisation (WHO), garlic is a healthy food that may have some antimicrobial properties. However, there is no evidence that it protects people from the coronavirus.

The best way to prevent getting the virus is to practise proper hygiene.

On April 14, Vavi shared on Twitter that he was taking vitamin C and chewing on garlic and raw ginger to boost his immune system.

"[I] also exercise to push the lungs a little bit but not too much," he said.

In a video on Sunday taken at his home, Vavi shared the news of his test results.

"I received my results and unfortunately for me, they are still positive," he said.

"Luckily, for my son, he is now negative. I would of course like to be negative like everybody else but I was forewarned by [health minister] Dr Zweli Mkhize that [recovery] depends on how big the impact of the coronavirus was on your body."