(CNN) The US National Institutes of Health said Wednesday it's starting a $470 million study to try to understand what's become known as long Covid—the long-term, sometimes serious effects of Covid-19.
The study will aim to include 30,000-40,000 people and will make use of digital data -- including input from wearable devices, the NIH said.
"We know some people have had their lives completely upended by the major long-term effects of Covid-19," NIH Director Dr. Francis Collins said.
"These studies will aim to determine the cause and find much needed answers to prevent this often-debilitating condition and help those who suffer move toward recovery."
The study, called Researching Covid to Enhance Recovery or RECOVER, will include researchers at more than 30 institutions across the country, the NIH said. They'll study existing and new patients with some of the mystifying conditions that show up after people supposedly get over the intense, acute effects of a bout with Covid-19.
"These post-Covid conditions are often referred to as long Covid, long-haul Covid, post-acute Covid-19, long-term effects of Covid, or chronic Covid. NIH refers to this scientifically as PASC- post-acute sequalae of SARS-CoV-2," Collins told a briefing.
"Persistent symptoms originate in multiple organs. The most common symptoms include pain, headaches, fatigue, what's called brain fog, shortness of breath, anxiety, depression, fever chronic cough and sleep disorders. PASC also includes multisystem inflammatory syndrome in children or MIS-C and also in adults -- MIS-A."
It's not clear what causes these symptoms and the study will seek to find what they might be.
"Is it a misfiring of the immune system that fails to reset after the infection with this coronavirus? Is it a triggering of some metabolic dysfunction?" Collins asked.
"We don't know. The diversity of symptoms and presentations leads us to believe that long Covid is not just one condition," he added.
"The only way, therefore, we're going to sort this out is with very large studies that collect lots and lots of data about symptoms, physical findings and laboratory measures."
The NIH said it would encourage researchers to recruit a variety of patients -- people of all ages, ethnicities, pregnant women and other. Researchers will be including input from the patients -- an unusual approach that Collins said is important to make sure the study covers all the bases.
Studies will also include data from wearable devices. Collins said the study has been put together in months, rather than the usual multi-year process for something so big and complex.
The NIH has set up a website where people who would like to volunteer can sign up.
Funding for the study comes from $1.15 billion Congress appropriated specifically for studying long Covid as part of the $1.9 trillion American Rescue Plan President Biden signed into law last March.
Collins said the $470 million for the study will leave money over to start research into possible treatments.
The study will look into whether various treatments used for severe cases of Covid-19 affect the risk of long Covid, whether vaccination affects risk, and will include people who had only mild symptoms of coronavirus infections, the NIH said.