According to a report on the ICC website, it was a bouncer from South African fast bowler Shabnim Ismail which hit her, leaving Mandhana visibly shaken.
Teams hit by COVID can field 9 players is one of the rules announced by the ICC on Thursday.
West Indies will play three-match T20I series before two Tests against New Zealand starting on December 3 in Hamilton. The first T20I will be played in Auckland on November 27.
Smriti Mandhana isn't actually known to be the most prolific T20 player -- her career T20 International average of 27.32 is middling at best. There have been failures too, but her ability to analyse and assess them honestly is a rarity in modern sport.
The Indian bowlers, who underperformed prior to the game, finally got their act together to limit New Zealand to 251 for nine in 50 overs.
India felt the absence of experienced pacer Jhulan Goswami as they suffered a three-wicket defeat in the second women's ODI against New Zealand in Queenstown on Tuesday.
Two-time champions Pakistan claimed third position at the ICC U-19 Cricket World Cup 2018 after their third-fourth position play-off match against Afghanistan was washed-out on Thursday without a ball being bowled, in Queenstown.