Persistent symptoms after COVID-19: an Australian stratified random health survey on long COVID

Objective

To determine the impact of persistent symptoms after coronavirus disease 2019 (COVID-19) in an Australian population.

Design, setting, participants

We conducted a statewide health survey of a stratified random sample of adults who had had a confirmed acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (COVID-19-positive group) and their close contacts (control group). The sample was drawn from Victoria's COVID-19 database between January 2020 and October 2022. Data were collected from 12 688 survey respondents between September 2022 and April 2023 (11 174 in the COVID-19-positive group and 1514 in the control group).

Main outcome measures

Persistent new symptoms, recovery, and daily function using validated questionnaires for fatigue, neurocognitive symptoms, anxiety, depression and quality of life.

Results

At a mean of 12.6 months after infection, 4560 respondents in the COVID-19-positive group (39.1%; 95% CI, 37.9–40.3%) reported at least one persistent new symptom, compared with 216 respondents in the control group (20.8%; 95% CI, 18.5–23.1%). A total of 1656 respondents (14.2%; 95% CI, 13.4–15.0%) were classified as having clinical long COVID using the criteria of at least one persistent new symptom and less than 80% recovery three months after the infection. Of the respondents with clinical long COVID, 535 (3.2%; 95% CI, 2.6–3.8%) reported at least moderate problems with usual activities at 12 months after their infection. The proportion of respondents with clinical long COVID was lower for those with more recent infections. The risk factors for clinical long COVID were female sex, age 40–49 years, infection severity, chronic illness, and past anxiety or depression. Factors associated with a decreased risk of having clinical long COVID included infection when the Omicron strain was dominant and infection when the Delta strain was dominant, as compared with when the ancestral strain of the virus was dominant.

Conclusion

Persistent symptoms after COVID-19 are common, though with a lower incidence following infection from less virulent strains. Although long COVID can be largely managed in primary care, a minority of people who have persistent symptoms and impaired function may require specialist care pathways, the effectiveness of which should be a focus of future research.