The pieces of the long Covid puzzle are falling into place.

I am a medical scientist and have been deeply involved in the study of long COVID since the early days of the pandemic. I have testified before the U.S. Senate as an expert witness on long COVID-19, published extensively on the topic, and was named one of Time magazine’s 100 Most Influential People in Health Care in 2024 for my research in this area.

During the first half of 2024, a series of scientific reports and articles on long-haul coronaviruses have shed light on this complex condition. In particular, this includes insights into how COVID-19 can continue to wreak havoc on multiple organs years after the initial viral infection, as well as emerging evidence of viral persistence and immune dysfunction that persists for months or years after the initial infection.

How COVID-19 affects the body in the long term

A new study published by my colleagues and I in the New England Journal of Medicine on July 17, 2024, shows that the risk of developing long COVID has declined over the course of the pandemic. In 2020, when the ancestral strain of SARS-CoV-2 was dominant and vaccines were not available, about 10.4% of adults who got COVID-19 developed long COVID. By early 2022, when the Omicron variants were dominant, that rate had dropped to 7.7% among unvaccinated adults and 3.5% among vaccinated adults. In other words, unvaccinated people were more than twice as likely to develop long COVID-19.

While researchers like me don’t yet have specific numbers on what the current rate will be in mid-2024, given the time it takes for long Covid cases to be reflected in the data, the influx of new patients into long Covid clinics was similar to what it was in 2024. In 2022.

We found that the decline was due to two main factors: the availability of a vaccine and changes in the characteristics of the virus — which made the virus less likely to cause severe acute infections and perhaps reduced its ability to survive in the human body long enough to cause chronic disease.