As many as 5% of people suffer long-term problems with their sense of taste or smell following Covid infection, research has found.
The international research team analysed 18 observational studies on adults with Covid-related changes to smell or taste, involving 3,699 patients.
They then used mathematical modelling to estimate self-reported rates of smell and taste recovery and to identify key factors associated with the duration and likelihood of recovery.
They found that:
- Smell loss may persist in 5.6% of patients following Covid recovery.
- Some 4.4% may not recover their sense of taste.
- At 30 days after initial infection, only 74% of patients reported smell recovery and 79% of patients reported taste recovery.
- Recovery rates increased with each passing month, reaching a peak of 96% for smell and 98% for taste after six months.
- Women were less likely to recover their sense of smell and taste than men, while patients with greater initial severity of smell loss and those with nasal congestion were less likely to recover their sense of smell.
Among limitations to the study, researchers noted that it did not take into account which Covid variant patients had recovered from. According to a recent large study, patients are less likely to develop long Covid with the currently dominant Omicron strain of the virus.
The paper published in the BMJ said that while most patients are expected to recover their sense of smell or taste within the first three months, ‘a major group of patients might develop long lasting dysfunction that requires timely identification, personalised treatment, and long term follow-up.
‘Our findings are likely to be of substantial relevance to general doctors and otolaryngologists in the counselling of patients with smell and taste disorders post-Covid-19,’ it added.
Professor Danny Altmann, professor of immunology at Imperial College London, said: ‘This is a strong and important study, alerting us once again to the difficulties inherent in charting the scale of long-term damage caused by Covid-19.
‘The authors conducted a rather rigorous meta-analysis across several cohorts, modelling the time to recovery of taste and smell. It goes without saying that problems with taste and smell are non-trivial for quality of life. This is part of a wider discussion about how we assess and address the persistent changes collectively termed long Covid.
‘Studies such as this alert us to the hidden burden out there of people suffering with persistent symptoms, but perhaps not having thought it worth contacting the GP on the assumption there wouldn’t be much to be done.’
The Office for National Statistics said in January that around 2% of the UK population – 1.3 million people – were experiencing Covid symptoms that lasted longer than four weeks after infection.