Do you tackle a problem without knowing what it is? The enemy was quickly identified. Long Covid is a lesser threat but is proving more difficult to pin down. Doctors don't know how common it is or how to respond to it.

The World Health Organization says that up to 200 have been recorded, with the most common being brain fog and fatigue, while others include loss of smell and dizziness. It's possible that there are more than one syndromes involved. It is still hard to find non- Covid causes in most of the symptoms.

It is obvious that it is common. There are an estimated 2 million sufferers in the UK who have continued or returned symptoms more than a year after falling ill. The number of people in the UK with Covid will increase. According to official data in the US, one in five people who have had Covid still suffer from symptoms after a year.

Older people and people with comorbidities are more likely to be affected by the effects of Covid, according to some evidence. The vaccine seems to offer some protection. This is nothing new. Some very fit people have also been hit. Men seem to suffer more than women.

Doctors are trialling different treatments for ongoing problems, such as pockets of the virus remaining in the gut, or the virus triggering an autoimmune disease, and scientists are looking into possible explanations. In Britain, the Royal College of Nursing has warned that services are not up to par. Though long Covid clinics have been set up by the National Health Service, demand far outstrips supply. Thousands of sufferers are travelling abroad to try and find a cure.

There are echoes of existing autoimmune diseases and ME/CFS, which are difficult to diagnose and treat, in long Covid. The biggest difference may be that Covid's seriousness and its spread have ensured greater attention and resources this time; patients with ME/CFS and some autoimmune illnesses who have long complained about the lack of interest and investment in research hope that it may lead to breakthrough that could help them

There will be no miracle cure if that materialises. Some may recover with little help, while others may benefit from different treatments. Other forms of help are needed by people who are unwell. British doctors who worked on the frontline in the Pandemic have said that they have not been given disability benefits.

Delays to or denial of personal independence payments can affect the recovery of patients as well as their state of mind, according to the Long Covid Support group. Supporting people as well as trying to cure them should be part of an appropriate response to Covid.