The announcement comes as a leading public health expert warned that long COVID could become 'a bigger public health problem' than excess COVID-19 deaths.
The new guideline is expected to be published before the end of the year as part of NICE's rapid COVID-19 guidance series, where guidelines are developed more quickly than the process normally used by the institute.
NICE and SIGN said that the guideline would include a formal definition of the disease and how to identify ongoing symptoms. It would also provide 'a definition of best practice investigation and treatment options to support the management of the condition across diverse communities,' they added.
Evidence from the House of Lords inquiry into long COVID earlier this year suggested that there could be as many as 60,000 people in the UK with symptoms that persist after the initial infection has cleared.
A report published on Monday by the Tony Blair Institute for Global Change cites data from the COVID Symptom Study, led by King’s College London, which suggests around 10% of patients who have had COVID-19 continue to suffer from symptoms for a month, while between 1.5% and 2% still experience symptoms after three months.
Professor Tim Spector, who is leading the King's College research, said in the report's foreword that long COVID 'could turn out to be a bigger public-health problem than excess deaths from COVID-19'.
Ongoing problems can be experienced by patients regardless of how severe their COVID-19 infection was and whether or not they were hospitalised. Symptoms of long COVID include breathlessness and fatigue as well as cardiovascular, lung, kidney, neurological and musculoskeletal problems.
Last month the RCGP said that GPs needed access to appropriate rehabilitation services in the community to help hundreds of thousands of patients with long-term COVID-19 symptoms. At the time the college called for up-to-date guidance on the effects of long COVID to ensure that family doctors can manage COVID-19 'in the most appropriate way' for patients.
Paul Chrisp, director of the Centre for Guidelines at NICE, said: 'There is growing evidence to suggest COVID-19 is a multi-system disease that for many people involves persistent symptoms with longer term impacts on their health. We want to ensure that clinicians have clear guidance on how best to support patients struggling with this newly emerging disease.'
RCGP chair Professor Martin Marshall said: 'Treating or managing any new virus or condition is a challenge for healthcare professionals. The college is delighted to be working with both NICE and SIGN to develop this guideline. It aims to support GPs and other healthcare professionals to ensure all patients with long term effects of COVID-19, including those diagnosed in the community irrespective of whether they received a positive test or not, can be cared for in the best possible way, based on the latest evidence.'
Roberta James, programme lead for SIGN, said: 'National guidance in this emerging field will help to align services with the needs of people who may be at risk of receiving inconsistent care. The guideline will support health and care services with recommendations on monitoring, testing, treatment options and the provision of advice and support for those who are experiencing these long-term effects.'