Kinetics of the PASC Index in Long COVID
- 1Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
Abstract
Background: The post‑acute sequelae of SARS‑CoV‑2 infection (PASC, “Long COVID”) remain difficult to evaluate because standardized diagnostic tools are limited. We applied the recently proposed PASC index (score ≥ 12) to describe the 12‑month trajectory of Long COVID symptoms. Methods: In this prospective cohort, adults with laboratory‑confirmed COVID‑19 were consecutively enrolled from November 2022 to February 2025. Long COVID was defined by a PASC index of ≥12 across 12 symptom domains persisting for at least 30 days post-infection. Symptom questionnaires were completed at 1, 3, 6 and 12 months after infection. Results: Among 183 participants, 48 (26.2%) met Long COVID criteria. Symptom assessments indicated that the proportion of participants meeting the Long COVID threshold declined from 27% at 1 month to 18% at 12 months, although this change was not statistically significant (p = 0.16). Participants classified as having Long COVID had consistently higher PASC index values across follow-up, while pairwise within-person comparisons showed no significant temporal changes in either the Long COVID or non-Long COVID group. These findings suggest that the overall symptom burden remained relatively stable over time, despite fluctuations in threshold status. Conclusion: During 12 months of follow-up, approximately one quarter of participants met the PASC index threshold at least once. Among participants with repeated assessments, PASC index scores showed limited within-person change, although differential non-response limits the interpretation of temporal prevalence estimates.
Related
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BibTeX
@article{kwon2026kinetics,
title = {{Kinetics of the PASC Index in Long COVID}},
author = {Kyungsup Kwon and Choi Young Jang and Woori Kim and JuYeon Son and Euijin Chang and Sung-Han Kim},
journal = {PLOS One},
year = {2026},
month = sep,
doi = {10.1371/journal.pone.0357670},
url = {https://doi.org/10.1371/journal.pone.0357670},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Kinetics of the PASC Index in Long COVID
AU - Kyungsup Kwon
AU - Choi Young Jang
AU - Woori Kim
AU - JuYeon Son
AU - Euijin Chang
AU - Sung-Han Kim
PY - 2026
DA - 2026/09/08
JO - PLOS One
DO - 10.1371/journal.pone.0357670
UR - https://doi.org/10.1371/journal.pone.0357670
AB - Background: The post‑acute sequelae of SARS‑CoV‑2 infection (PASC, “Long COVID”) remain difficult to evaluate because standardized diagnostic tools are limited. We applied the recently proposed PASC index (score ≥ 12) to describe the 12‑month trajectory of Long COVID symptoms. Methods: In this prospective cohort, adults with laboratory‑confirmed COVID‑19 were consecutively enrolled from November 2022 to February 2025. Long COVID was defined by a PASC index of ≥12 across 12 symptom domains persisting for at least 30 days post-infection. Symptom questionnaires were completed at 1, 3, 6 and 12 months after infection. Results: Among 183 participants, 48 (26.2%) met Long COVID criteria. Symptom assessments indicated that the proportion of participants meeting the Long COVID threshold declined from 27% at 1 month to 18% at 12 months, although this change was not statistically significant (p = 0.16). Participants classified as having Long COVID had consistently higher PASC index values across follow-up, while pairwise within-person comparisons showed no significant temporal changes in either the Long COVID or non-Long COVID group. These findings suggest that the overall symptom burden remained relatively stable over time, despite fluctuations in threshold status. Conclusion: During 12 months of follow-up, approximately one quarter of participants met the PASC index threshold at least once. Among participants with repeated assessments, PASC index scores showed limited within-person change, although differential non-response limits the interpretation of temporal prevalence estimates.
SN - 1932-6203
ER -