One in every 20 people who catch Covid-19 have long-term smell or taste problems as a result, according to a new study.

This could mean that millions of people around the world may have suffered smell and taste issues for at least six months following a Covid-19 infection.

Loss or change of sense of smell or taste can suffer “severe distress”, academics said as they urged health systems to be prepared to support people who often feel “isolated” when dismissed by clinicians.

They said daily activities such as smelling coffee and testing the flavour of food can become “disgusting and emotionally distressing”.

The study comes as the NHS announced plans to improve long Covid services for people suffering ongoing illness after infection.

Under new guidelines, patients with suspected long Covid in England will have an initial assessment within six weeks.

Meanwhile, the new study, published in The BMJ, reviewed data from 18 studies involving 3,699 patients.

Based on the data, the team of international researchers, including some from the UK, used modelling to estimate how many people go on to suffer from altered taste or smell for at least six months after a Covid-19 infection.

They concluded that an estimated 5.6% of Covid patients suffer smell dysfunction for at least six months and 4.4% have an altered taste

In July there had been some 550 million infections worldwide, which means 15 million may have had lasting smell problems and 12 million patients had taste problems for at least six months, the authors estimated.

Women were less likely to recover their sense of smell and taste, they found.

And patients who suffered the most at the initial infection were also more likely to have lasting effects.

In a linked editorial, a team of Italian academics wrote: “About 5% of people report smell and taste dysfunction six months after Covid-19, and given that an estimated 550 million cases of Covid-19 have been reported worldwide as of July 2022, large numbers of patients will be seeking care for these disabling morbidities.

“Health systems should therefore be ready to provide support to these patients who often report feeling isolated when their symptoms are overlooked by clinicians.”

They said people “only realise the importance of smell when it is lost” and they can be “severely distressed” when they lose these senses.

“Loss of smell and taste adversely affects quality of life by depriving those affected of several everyday pleasures and social bonds,” the team, led by Paolo Boscolo-Rizzo from the University of Trieste, wrote.

“People can also experience anorexia, food aversions, malnutrition, anxiety, and depression,” they added.

They highlighted that parosmia – the experience of a distorted sense of smell – means that for many this “transforms a pleasant odour into an unpleasant one”.

This means that “daily activities such as smelling coffee and sensing the flavour of food can become disgusting and emotionally distressing”.

Meanwhile, NHS England has set out its ‘Long Covid Action Plan’ for thousands of people with ongoing symptoms.

Under the plans, people will be able to access services closer to home and be given an initial assessment within six weeks at a specialist clinic.

It is hoped that the £90 million service will reduce the need for a patient to return to their GP for multiple different symptoms.

The money will be used to fund 90 specialist long Covid clinics, 14 hubs for children and young people and investment in training and guidance to support GP teams in managing the condition.

Dr Kiren Collison, GP and chair of the NHS long Covid taskforce said: “Long Covid can be devastating for those living with it, and while we continue to learn more about this new condition, it’s important people know they’re not alone, and that the NHS is here for them.

“In just under two years, the NHS has invested £224 million to support people experiencing long term effects from Covid – from setting up specialist clinics, hubs for children, and an online recovery platform, to providing training for GP teams.

“Today’s plan builds on this world-leading care, to ensure support is there for everyone who needs it, and that patients requiring specialist support can access care in a timely and more convenient way.”

Meanwhile, a separate study has concluded that face shields do not provide high level Covid protection.

Some use the shields as a method of protecting themselves from the virus when they are unable to use masks.

But a new study from academics at the University of East Anglia assessed the 13 styles of face shield in a laboratory setting.

Researchers found that while all the face shields provided some protection, none gave high levels of protection against “external droplets contamination”, according to the study, published in the journal, American Journal of Infection Control.