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Long COVID-19 symptoms may appear for months after infection

A new study from the CDC shows that long COVID-19 symptoms may emerge months after the initial SARS-CoV-2 infection. The study also found that individuals with long COVID-19 symptoms had significant activity limitations.

Let’s examine this study and review its conclusions.

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Long COVID-19 paper from the CDC

In a paper published on 11 August 2023 in the MMWR Morbidity and Mortality Weekly Report, Sharon Saydah, Ph.D., CDC’s National Center for Immunization and Respiratory Diseases, and coauthors examined data from the prospective multicenter INSPIRE study, which is a project to understand the long-term health outcomes in recently tested adults, both negative and positive, who have suspected COVID symptoms at the time of their test.

A total of 1,741 people completed all quarterly surveys over 12 months, including 1,288 COVID test-positive and 453 COVID test-negative participants. Most participants were female. Outcomes included self-reported symptoms in eight categories: extreme fatigue; cognitive difficulties; cardiovascular; pulmonary; musculoskeletal; gastrointestinal; constitutional; or head, eyes, ears, nose, and throat.

Here are the key results:

  • Approximately 16% of study participants had symptoms that lasted 12 months after their initial SARS-CoV-2 test.
  • At 3, 6, 9, and 12 months after testing, some people had ongoing symptoms, while others had emerging symptoms not reported previously.
  • The prevalence of any symptom decreased substantially from baseline to 3-month follow-up — from 98.4% to 48.2% for COVID-positive participants, and from 88.2% to 36.6% for COVID-negative participants.
  • At 12 months, symptom prevalence was similar between groups, at 18.3% in the COVID-positive group and 16.1% in the COVID-negative group.

The authors concluded:

Given the findings that approximately 16% of persons who have had an acute COVID-like illness might experience persistent symptoms through 12 months, post-COVID–like conditions could represent a substantial impact on health and the health care system. This report highlights the patterns of symptoms after acute COVID-like illness by providing estimates of symptom prevalence for both ongoing and emerging symptoms. Improved understanding of the persistent and fluctuating nature of symptoms could guide clinical care and public health response to post-COVID–like conditions.


Once again, we have more data that shows that long COVID-19 is an important outcome of the initial infection. It doesn’t hit everyone and it does not show up immediately after getting a negative COVID-19 test, but it happens to a significant number of people.

The only thing I wish this study showed was a difference in long COVID-19 between vaccinated and unvaccinated populations, but there are studies ongoing that will be published soon.

This study does show that even if you have negative tests after a COVID-19 infection, you are still at risk of new and serious symptoms.


Michael Simpson

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