Long COVID and its risk factors in migrants: a nationwide register study from Sweden, 2025, Cederström et al

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Long COVID and its risk factors in migrants: a nationwide register study from Sweden

Agneta Cederström, George Frederick Mkoma, Thomas Benfield, Charles Agyemang, Marie Nørredam, Mikael Rostila

Background
Many studies have found more severe COVID-19 outcomes in migrants and ethnic minorities throughout the COVID-19 pandemic, while recent evidence also suggests higher risk of longer-term consequences. We studied the risk of a long COVID diagnosis among adult residents in Sweden, dependent on country of birth and accounting for known risk factors for long COVID.

Methods
We used linked Swedish administrative registers between March 1, 2020 and April 1, 2023, to estimate the risk of a long COVID diagnosis in the adult population that had a confirmed COVID-19 infection. Poisson regressions were used to calculate incidence rate ratios (IRR) of long COVID by country/region of birth. The contribution of sex, preexisting health status, disease severity, vaccination status, and socioeconomic factors to differences in long COVID diagnosis by country/region of birth were further investigated.

Results
Of the 1,869,188 persons diagnosed with COVID-19 that were included, 7539 had received a long COVID diagnosis. Compared with residents born in Sweden, we found higher risks of long COVID among migrants from East Europe (IRR: 1.44 CI: 1.29–1.60), Finland (IRR: 1.36 CI: 1.15–1.61), South Asia (IRR: 1.28 CI: 1.03–1.59), Other Asia (IRR: 1.35 CI: 1.13–1.62), Other Africa (IRR: 1.48 CI: 1.17–1.87), and the Middle East (IRR: 1.43 CI: 1.27–1.63) in models adjusted for age and sex. We discovered that disease severity, i.e., whether the person was hospitalized (IRR: 18.6 CI: 17.3–20.0) or treated in an intensive care unit (IRR: 120.5 CI: 111.7–129.8), primarily contributed to the higher risk of long COVID found in migrants while the contribution of vaccinations and social conditions were moderate. Preexisting health problems did not contribute to the increased risk of long COVID in migrants.

Conclusions
The greater exposure and impact of the COVID-19 virus among migrants also affected longer-term consequences. Disease severity was the most important risk factor for long COVID in migrants. The findings emphasize the need for targeted health interventions for migrant communities during an infectious disease pandemic, such as strategic vaccination campaigns and extending social insurance schemes, focusing on reducing disease severity to mitigate the longer-term health consequences of an infection.

Link | PDF (BMC Medicine) [Open Access]

 

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The effect of migrants having a higher risk of long COVID seems to be mainly due to them having a higher risk of severe COVID. After controlling for severity, the effect disappears or even reverses for several countries.

the estimates were drastically reduced when adjusting for disease severity. The incidence rate ratios were actually lower for migrants from Horn of Africa (M3 IRR: 0.55 CI: 0.44–0.68), the Middle East (M3 IRR: 0.76 CI: 0.69–0.83), and Other Asia (M3 IRR: 0.73 CI: 0.57–0.92), when compared to residents born in Sweden, and had completely attenuated for migrants from East Europe (M3 IRR: 0.96 CI: 0.87–1.05), Finland (M3 IRR: 0.95 CI: 0.81–1.10), and Other Africa (M3 IRR: 0.84 CI: 0.67–1.05) after adjusting for disease severity.]

These findings align with previous studies that have found higher risks of ICU and death due SARS-COV-2 infection in migrants throughout the pandemic. The higher rates of ICU care in migrant and ethnic minorities can be understood in light of higher exposure to the virus in earlier stages of the pandemic in which socioeconomic and living conditions contributed to higher contagion among these groups at a time with less developed treatment options [26,27,28], perhaps in conjunction with disparities in health care access and health care seeking behavior. Lower rates of vaccination in migrants and poorer socioeconomic conditions (education, income, and occupational skill level) did mediate some of the association between country of birth and long COVID while underlying health problems did not contribute to this association.