Why have “long COVID” cases become less frequent and less severe over time?
This morning, the Infectious Diseases Society of America (IDSA) held a webinar to brief the public on what is known about post-acute sequalae of COVID-19, often called “long COVID.”
The focus for the briefing was the latest data from the INSPIRE study. INSPIRE is funded by the US Centers for Disease and Control (CDC), and sought to characterize the prevalence and variety of symptoms after COVID-19 infection.
The study analyzed post-COVID-19 conditions at 3 key points in time: the period before Delta became the most predominant variant, the Delta period, and the Omicron period. INSPIRE included 8 countries and over 6000 study patients.
Michael Gottlieb, MD, RDMS, a co-principal investigator of the INSPIRE study at the Rush University Medical Center, fielded questions and gave an overview of his team’s findings. Gottlieb is an associate professor at Rush University Medical Center, as well as the director of emergency ultrasound in their Department of Emergency Medicine.
Gottlieb emphasized the prevalence of long COVID—1 in 8 infected individuals had severe fatigue lasting at least 3 months after infection. To those suffering the debilitating effects of long COVID, Gottlieb said, “You are not alone in this.”
One objective of the INSPIRE study was to quantify long COVID, specifically the number of symptoms and the number of people suffering. “We need to understand what people are going through,” said Gottlieb.
Across the 3 variant time periods, INSPIRE compared fatigue severity, fatigue symptoms, individual and organ system-based symptoms, and presence of ≥ 3 total symptoms among participants with and without long COVID.
The variety of symptoms identified during the INSPIRE trial suggest that long COVID manifests differently in different people. “Long COVID is not a singular concept,” Gottlieb said. “There are phenotypes, or versions of long COVID.”
The other guest speaker during the briefing was Paul E. Sax, MD, FIDSA. Sax is editor-in-chief of Clinical Infectious Diseases, the journal that published the INSPIRE study. Sax said he was excited to see this study submitted to Clinical Infectious Disease, citing the large control group of uninfected participants as adding credibility to INSPIRE’s findings.
“This study highlights the importance of long COVID and how much we need to learn,” Sax said.
A particularly interesting finding was that rates of long COVID have decreased over the 3 variant time periods. Gottlieb said this observation was impetus for the INSPIRE study, as the team wanted to determine whether it was the mutating variants or another factor causing fewer long COVID infections over time.
Gottlieb and Sax concluded that people getting vaccinated over time drive down the rates of long COVID. Indeed, the INSPIRE study found that COVID-19 vaccination reduces the risk of long COVID across variants.
“Those who were vaccinated had lower rates of long COVID across all time periods,” Gottlieb emphasized. Sax reiterated, “This is one of the benefits we see from vaccination.”
In addition to occurring less frequently, long COVID cases have become less severe since the beginning of the pandemic. “We’re seeing fewer cases of organ damage long COVID,” Pax said.