Researchers at Polytechnic University interviewed 3,011 residents contacted by telephone at random between December 2020 and February last year. It found 12.4 per cent of respondents exhibited symptoms of PTSD, including inadvertently thinking about the pandemic, growing irritable or angry and denying the existence of the coronavirus.

But the researchers warned the situation could have worsened during the fifth wave, which was now subsiding, when hundreds of thousands of new infections and thousands of deaths overwhelmed the healthcare system. They warned that between 30 and 40 per cent of residents could be afflicted with PTSD symptoms.