A GP and former member of the Medical Council has been found guilty of professional misconduct over his posts on social media during the pandemic, which were highly critical of Covid-19 vaccines and public health guidelines.

A fitness-to-practise committee of the Medical Council also found allegations of professional misconduct proven against Marcus de Brun over his attendance and comments made at a public rally in August 2020, when he failed to maintain social distancing and wear a facemask.

The ruling followed a medical inquiry held over seven days since last September into 10 separate counts of professional misconduct against Dr de Brun – a married father of four who had operated his own practice in Rush, Co Dublin – over his criticism of vaccines, lockdowns, facemasks and various public health guidelines.

Most of the allegations related to 67 posts by the GP on Twitter (now X) on dates between May 2020 and October 2021.

In its ruling, the committee found seven allegations of professional misconduct proven, including four for which the actions of Dr de Brun were considered both “disgraceful and dishonourable” and falling seriously short of the standards expected of doctors.

Such findings related to his posts about Covid-19 vaccines, particularly in relation to children, lockdowns and his attendance at a public rally at the Customs House in Dublin on 22 August 2020 when he was also accused of failing to wear a facemask and observe social distancing at a demonstration attended by up to 7,000 people.

The hearing is continuing with submissions by both lawyers for the Medical Council and Dr de Brun on the appropriate sanction.