Ms Tóibín, a sister of party founder, Peadar Tóibín, has worked as a pharmacist in addiction and mental health services in Dublin Bay South for 15 years.
She also worked as an inspector of the Pharmaceutical Society of Ireland and says she has seen first-hand the many challenges that patients seeking treatment in the health service suffer.
“The Dublin Bay South by-election is in many ways a referendum on how this government mismanaged the Covid crisis,” Ms Tóibín said following the announcement of her selection by the party.
“The majority of people who died with Covid caught Covid in a hospital or a nursing home, both run or regulated by the Government.
“This is an incredible situation.
“The most vulnerable were the most exposed. We in Aontú were the first to call for a full investigation into the manner in which the government mismanaged this crisis. This mismanagement is not over.
“Many seriously ill patients with life threatening diseases are still not getting the treatment they need due to the fact that the health services are not fully open”.