Two Years Later, We Still Don’t Understand Long Covid. Why?

Depending on the data you look at, between 10 and 40 percent of people who get Covid will still have symptoms months later. For some, those symptoms will be modest. A cough, some fatigue. For others, they’ll be life-altering: Debilitating brain fog. Exhaustion. Cardiovascular problems. Blood clotting.This is what we call long Covid. It’s one term for a vast range of experiences, symptoms, outcomes. It’s one term that may be hiding a vast range of maladies and causes. So what do we actually know about long Covid? What don’t we know? And why don’t we know more than we do?Dr. Lekshmi Santhosh is an assistant professor at UCSF Medical Center, and the founder and medical director of UCSF’s long Covid and post-ICU clinic. Her clinic opened in May 2020 and was one of the first to focus on treating long Covid patients specifically. We discuss the wildly broad range of symptoms that can qualify as long Covid; the confusing overlaps between Covid symptoms and other diseases; whether age, race, sex and pre-existing conditions affect a person’s chances of contracting long Covid; why it’s so difficult to answer a seemingly simple question like, “How many people have gotten long Covid?”; what to make of a recent study that seemingly undermines the biological existence of long Covid; how worried we should be about correlations between Covid and medical disasters like heart attacks, strokes and abnormal blood clotting; and more.Mentioned:“Post–COVID Conditions Among Adult COVID-19 Survivors Aged 18–64 and ≥65 Years — United States, March 2020–November 2021” by Lara Bull-Otterson, Sarah Baca1, Sharon Saydah, Tegan K. Boehmer, Stacey Adjei, Simone Gray and Aaron M. Harris“Long COVID after breakthrough SARS-CoV-2 infection” by Ziyad Al-Aly, Benjamin Bowe and Yan Xie“A Longitudinal Study of COVID-19 Sequelae and Immunity: Baseline Findings” by Michael C. Sneller, C. Jason Liang, Adriana R. Marques, et al.“Positive Epstein–Barr virus detection in coronavirus disease 2019 (COVID-19) patients” by Ting Chen, Jiayi Song, Hongli Liu, Hongmei Zheng and Changzheng Chen“Risk factors and disease profile of post-vaccination SARS-CoV-2 infection in UK users of the COVID Symptom Study app” by Michela Antonelli, Rose S. Penfold, Jordi Merino, Carole H. Sudre, Erika Molteni, Sarah Berry, et al.“Understanding and Improving Recovery From COVID-19” by Aluko A. Hope“Markers of Immune Activation and Inflammation in Individuals With Postacute Sequelae of Severe Acute Respiratory Syndrome Coronavirus 2 Infection” by Michael J. Peluso, Scott Lu, Alex F. Tang, Matthew S. Durstenfeld, et al.Book Recommendations:In Shock by Dr. Rana AwdishEvery Deep-Drawn Breath by Wes ElyMountains Beyond Mountains by Tracy KidderWe're hiring a researcher! You can apply here or by visiting nytimes.wd5.myworkdayjobs.com/NewsThoughts? Guest suggestions? Email us at ezrakleinshow@nytimes.com.You can find transcripts (posted midday) and more episodes of “The Ezra Klein Show” at nytimes.com/ezra-klein-podcast, and you can find Ezra on Twitter @ezraklein. Book recommendations from all our guests are listed at }https://www.nytimes.com/article/ezra-klein-show-book-recs.“The Ezra Klein Show” is produced by Annie Galvin, Jeff Geld and Rogé Karma; fact-checking by Haylee Millikan and Michelle Harris; original music by Isaac Jones; mixing by Jeff Geld; audience strategy by Shannon Busta. Our executive producer is Irene Noguchi. Special thanks to Kristin Lin, Kristina Samulewski, Dr. Ziyad Al-Aly and Lauren Nichols.