When compared to people who avoided COVID-19 in the same time period, individuals who reported having COVID in early 2020 were also 1.67 times more likely to have clinically significant levels of anxiety after 13 months.

The study relied on participants self-reporting COVID-19, as limited testing was available at the beginning of the pandemic. However, the levels of reported infection are similar to two other key studies conducted at a similar time.

They also found that having a mental health condition before the pandemic was associated with increased odds of contracting COVID-19. Possible reasons for this may include lifestyle factors such as smoking, physical health vulnerabilities linked to poor mental health, and lower levels of adherence to government COVID-19 restrictions.

Previous studies have reported increases in anxiety and depression symptoms after patients likely contracted COVID-19, but only around six months later. This study suggests that the virus may have a longer-lasting mental health impact than previously thought.

The researchers are calling for medical professionals to take their findings into account when treating patients who have had COVID-19.

Professor O'Connor said: "The findings highlight the importance for GPs and other healthcare professionals to be vigilant to these longer-lasting symptoms and to put in place treatments and support for mental health, as well as physical health, for patients who may have contracted COVID-19 infection."

The researchers highlighted that long COVID may also be a factor in the findings, as its long-term symptoms such as fatigue, sleep disturbance, headaches, brain fog, loss of taste and smell and breathlessness could contribute to anxiety, depression, and poor well-being.

They concluded that further investigation was needed to identify the causes of the long-term impacts of COVID-19 on mental health.