tetano
Editor, Senior Moderator
PLoS One
. 2026 Sep 8;21(9):e0357670.
doi: 10.1371/journal.pone.0357670. eCollection 2026.
Kyungsup Kwon 1 , Choi Young Jang 1 , Woori Kim 1 , JuYeon Son 1 , Euijin Chang 1 , Sung-Han Kim 1
Affiliations Expand
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.
. 2026 Sep 8;21(9):e0357670.
doi: 10.1371/journal.pone.0357670. eCollection 2026.
Kinetics of the PASC Index in Long COVID
Kyungsup Kwon 1 , Choi Young Jang 1 , Woori Kim 1 , JuYeon Son 1 , Euijin Chang 1 , Sung-Han Kim 1
Affiliations Expand
- PMID: 42709774
- PMCID: PMC13552729
- DOI: 10.1371/journal.pone.0357670
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.