There has been no official statement about the death of either of Vladimir Putin's daughters. No credible news agencies have reported it.
The Russian president has two daughters from his former wife, Lyudmila Aleksandrovna Ocheretnaya– Katerina Tikhonova and Maria Vorontsova. Reports about his daughter being inoculated did not mention which of his daughters was administered the vaccine. He reportedly stated that she had minor side effects such as slight fever, and was later feeling well. He is also quoted as saying that “she has a high number of antibodies.”
On August 15, 2020, Toronto Today published an article claiming that Katerina Tikhonova had died after receiving a second dose of the vaccine. The article reports that Putin's younger daughter Katerina Tikhonova, 'suffered a rise in temperature shortly after her second injection and then suffered a seizure. Doctors were not able to reverse the side-effects of the vaccine, and she was pronounced dead late yesterday evening'. The information is attributed to an unnamed source ‘in Russia’s inner circles.’ A video of a volunteer who took part in a clinical trial for a Russian COVID-19 vaccine with false claims that the volunteer was Putin's daughter had also gone viral.
No other credible news agencies have published any reports about the death of Putin’s daughter. No official statements corroborating the same have been issued by the Kremlin either.
The COVID-19 pandemic has given rise to a lot of potentially dangerous misinformation. For reliable advice on COVID-19 including symptoms, prevention and available treatment, please refer to the World Health Organisation or your national healthcare authority.