This is a summary, written by members of the CITF Secretariat, of:

Reyes Domingo F, Waddell LA, Cheung AM, Cooper CL, Belcourt VJ, Zuckermann AME, Corrin T, Ahmad R, Boland L, Laprise C, Idzerda L, Khan A, Jaramillo Garcia A. Prevalence of long-term effects in individuals diagnosed with COVID-19: a living systematic review. 2021 Jun 6. doi:10.1101/2021.06.03.21258317.

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

Researchers, including CITF-supported researcher Dr. Angela Cheung, conducted a systematic review to document the prevalence of post-COVID-19 symptoms in people in the short term (4-12 weeks after being diagnosed with COVID-19), as well as in the long term (after more than 12 weeks post-diagnosis). In this pre-print, therefore not yet peer-reviewed, the researchers suggest that most confirmed COVID-19 patients continued to experience one or more symptoms in the short-term (83%) and long-term (56%) after initial diagnosis. This has important implications for health systems globally as well as national and international public health organizations to continue supporting those experiencing post-COVID-19 symptoms.

Known as long COVID, post-COVID condition, chronic COVID syndrome and post-acute sequelae of SARS-CoV-2 infection (PASC), this condition refers to an individual continuing to exhibit a variety of symptoms even after being cleared of an acute SARS-CoV-2 infection. As we transition into year two of the pandemic, more and more research on post-COVID-19 conditions is being conducted, to better understand the health burden of this disease. This is important both in the short-term (four to twelve weeks post-COVID) and the long term (over 12 weeks post-COVID), to anticipate and plan for the necessary health programming and resource allocation needed to support survivors.

Key points:

  • 83% of laboratory-confirmed COVID-19 patients continued to experience one or more symptoms in the short-term; 56% experienced long-term symptoms.
  • The most prevalent symptoms in the short-term (4-12 weeks after diagnosis) were fatigue, general pain or discomfort, shortness of breath, sleep disturbances, anxiety, and cough. More than half of the individuals reported feeling ill or not back to pre-COVID health in the short-term.
  • The most prevalent symptoms in the long-term (>12 weeks following diagnosis) were fatigue, general pain or discomfort, and sleep disturbances. 42% of individuals in the long-term category reported continued decrease in lung functioning that was not apparent pre-COVID.


Thirty-six studies met the inclusion criteria for the systematic review. Most studies (28) included data for individuals with laboratory-confirmed COVID-19 and eight included data for individuals who were clinically diagnosed with COVID-19. The majority of the studies were conducted in Europe (57%). Altogether, over 100 symptoms attributed to long-COVID were reported.

For patients in the long-term category, fatigue, general pain or discomfort, and sleep disturbances were the most prevalent symptoms. Anxiety, depression, post-traumatic stress disorder (PTSD), shortness of breath, and hair fall/loss followed, with a roughly 22-23% prevalence for each of these symptoms in the study population. Importantly, the most prevalent clinical complication from acute COVID-19 was unresolved impaired pulmonary function (42%). Indeed, many individuals were unable to return to work following a COVID-19 diagnosis due to ongoing symptoms, even after recovering from the acute infection.

At month 16 of this evolving pandemic, we are still learning about the novel SARS-CoV-2 virus and are just beginning to scratch the surface of post-COVID-19 conditions. The authors note that most studies in this systematic review included adults who may have experienced severe enough disease to warrant hospitalization. Data is less available for children and for those whose COVID-19 infection was mild or asymptomatic. In addition, longitudinal studies following survivors are only in their infancy. Research is ongoing to better understand the burden of post-COVID-19 conditions as well as the social and economic impacts of this disease. This is an important and growing area of research because our health systems will require this evidence to develop necessary interventions and programming to support long COVID patients.