Health outcomes one year after Omicron infection among 12,789 adults: a community-based cross-sectional study, 2025, Zhang

https://www.thelancet.com/journals/lanwpc/article/PIIS2666-6065(25)00044-6/fulltext

Articles
Online first
101507
March 13, 2025
Open access
Health outcomes one year after Omicron infection among 12,789 adults: a community-based cross-sectional study
Hui Zhang Peng Yang Xiaoying Gu Ying Sun Rongling Zhang Daitao Zhang

Summary

Background
Characterizing the paradigm and impact of long COVID is crucial for addressing this worldwide health challenge. This study aimed to investigate the prevalence of long COVID one year after primary Omicron infection and characterize differences in long-term health consequence between participants with persistent long COVID and those who fully recovered.

Methods
This a community-based cross-sectional study conducted from December 2023 to March 2024 at the China-Japan Friendship Hospital and 16 administrative districts in Beijing. 12,789 participants infected with Omicron between December 2022 and January 2023 were recruited through stratified multistage random sampling and included in the final analysis. Of them, 376 participants with persistent long COVID and 229 without long COVID were matched for further physical examinations. The primary outcome was the prevalence of long COVID one year after infection. Secondary outcomes included muscle strength, exercise capacity, health-related quality of life (HRQoL), mental health, work status, laboratory tests, and examinations.

Findings
Among 12,789 participants (media [IQR] age, 48.4 [37.3 to 61.4] years; 7817 females [61.1%]), 995 of them (7.8%) experienced long COVID within one year, with 651 (5.1%) having persistent symptoms. Fatigue (598/995 [60.1%]) and post-exertional malaise (367/995 [36.9%]) were the most common symptoms. Brain fog had the lowest resolution proportion as 4.2% within one year. The odds of long COVID increased with reinfections (odds ratios for one reinfection 2.592 [95% CI: 2.188 to 3.061]; two or more: 6.171 [3.227 to 11.557]; all p < 0.001). Participants with persistent long COVID had markedly lower muscle strength (upper-limb: 26.9 ± 12.4 vs. 29.1 ± 14.5 Kg; lower-limb: 40.0 [27.0 to 62.0] vs. 43.0 [28.0 to 59.0] s), worse exercise capacity and poorer HRQoL, and meaningful difference in laboratory tests results compared to those without long COVID. They also exhibited significantly higher proportions of abnormal lung function (FEV1 %pred<80%: 13.0% vs. 2.0%; DLco %pred<80%: 32.7% vs. 19.9%) and lung imaging abnormalities (23.5% vs. 13.6%).

Interpretation
The considerable health burden of long COVID and the progression of neurological symptoms following Omicron infection warrant close monitoring. Utilizing professional questionnaires and developing reliable diagnostic tools are necessary for improving diagnosis and treatment of long COVID.

Funding
This work was supported by Beijing Research Center for Respiratory Infectious Diseases (BJRID2024-012), Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences (2022-I2M-CoV19-005/CIFMS 2021-I2M-1-048), the National Natural Science Foundation of China (82241056/82200114/82200009), the New Cornerstone Science Foundation.

Keywords

1. Long covid
2. COVID-19
3. Health outcomes
4. Lung function
5. Neurological

Research in context

Evidence before this study
Omicron has become the most prevalent strain globally, with 4.2–18.2% of individuals who were infected experienced long COVID. Several risk factors for the development of long COVID have been identified. However, as of September 21, 2023, a PubMed search indicated that data on the prevalence of long COVID after primary Omicron infection in representative populations, as well as the factors contributing to its persistence, remained scarce. The diagnosis of long COVID, which primarily depends on patient-reported symptoms, continues to be challenging, with no universally accepted objective diagnostic tools available.

Added value of this study
This community-based cross-sectional study included 12,789 highly vaccinated adults primarily infected with Omicron, with 7.8% of them developed long COVID within one year, and 5.1% had persistent long COVID (LC) at 1-year after infection. The risk of long COVID increased with reinfection in a dose-dependent manner. While risk factors for long COVID were identified, they did not further contribute to its persistence. The highest rate of symptom recovery occurring within 6 months after infection, except for brain fog and cognitive impairment. Compared to participants without long COVID, those with persistent LC exhibited higher levels of leukocytes, triglycerides, fibrinogen, and myoglobin. They also had significantly higher proportions of abnormal lung function, and lung imaging abnormalities.

Implications of all the available evidence
Nearly 5% of highly vaccinated adults experienced persistent LC one year after primary Omicron infection. Reinfection increased the risk for the development of long COVID. Participants with persistent LC displayed higher levels in several laboratory tests parameters, alongside more prevalent abnormal lung function, all of which could serve as diagnostic indicators for long COVID. The findings of this study underscore the significant long-term health impacts of long COVID on multiple organ systems and emphasize the necessity of ongoing monitoring and targeted interventions to address the persistent symptoms experienced by suffered individuals.

 

65.7% of persistent LC participants exhibited clinically important fatigue, 34.0% were suggestive of PEM and 5.5% were suggestive of myalgic encephalomyelitis/chronic fatigue syndrome, all of which were nearly twice as high as those in no LC (35.9%, 12.8%, and 1.8%, respectively). These results across different persistent LC subgroups were detailed in Table 3.