Renate Leismann

 

German singers Renate and Werner Leismann (sister and brother) appeared in German TV-show HITPARADE 1973 with Renate wearing an early denim vest.

Red, blue and denim seems to have been some kind of signature while early 70s promotion work:

俏探女嬌娃

 

The Deadly Angels ( 俏探女嬌娃 / Qiao tan nu jiao wa ) is a Marial Arts movie from Hong Kong published in 1977. 

I found a denim vest appearance there by Swiss actress Evelyn Kraft. She wears a white denim outfit with bell bottom jeans and denim vest here. White denim clothes were also part of the fashion in the 1970s, but a smaller and hardly overshadowed by the presence of indigo denim clothes.

Possibly there is a second denim vest performance, but I think, it is only a vest inspired sleeveless blue  womens top, not a blue jean vest, worn by Hong Kong actress Susan Yam-Yam Shaw in the sequence with the knife thrower. 

Here are two shots from another better resoluted source to compare. Still don't believe, its a denim waistcoat.