Mizoram Chief Minister Zoramthanga's elder sister Lalvuani died due to COVID-19 at a hospital on Monday.
Lalvuani, 88, died while undergoing treatment at the Zoram Medical College (ZMC) near Aizawl.
"It is with deep sorrow that I announce the demise of my beloved elder sister Lalvuani (88-years) this morning at 11:30 am," the chief minister tweeted.
Lalvuani, the third eldest of seven siblings, was bed-ridden for months due to asthma and age-related complications, family sources said.
She was diagnosed with COVID-19 on September 22 and shifted to the ZMC, they said.
Mizoram on Monday reported 527 new cases of COVID-19, pushing the state's tally to 88,693, a government bulletin said.
The death toll rose to 295 as three more people succumbed to the infection, it said.
The positivity rate was 31.77 per cent as the fresh cases were detected after testing 1,659 sample tests, it added.
Aizawl reported the highest number of new cases at 550, followed by Lawngtlai (20) and Champhai (16).
At least 131 children were among the newly-infected people, the bulletin said.
Mizoram now has 15,485 active cases, while 72,913 patients have recovered.