Incidence Trends and Co-Diagnosis of Post–COVID-19 Condition in the Active Duty Population

Introduction: Long COVID, also known as Post–COVID-19 Condition (PCC) is characterized by the persistence or development of symptoms following SARS-CoV-2 infection. Post–COVID-19 Condition has the potential to impact military readiness, and yet the incidence among active duty service members (ADSM) is unknown. The objective of this study is to assess the incidence of diagnosed PCC, explore demographic associations, and identify common co-occurring diagnoses among ADSM. Materials and Methods: We conducted a repeated cross-sectional study using the Military Health System Data Repository (MDR). The MDR was queried for care records containing the ICD-10 code for PCC, U09.9, from October 2021 to October 2022. Incidence was calculated using the monthly counts, although Incidence Rate Ratios were calculated using a Poisson regression model, adjusting for age, sex, rank, race/ethnicity, and region. The frequency of co-occurring diagnoses with PCC encounters was analyzed to identify the top co-occurring diagnoses. Results: A total of 7,171 ADSM were diagnosed with PCC. The average monthly incidence of PCC was 4.7 per 10,000 ADSM. Females had 3.70 times (95% CI, 3.50-3.90) the adjusted incident rate ratio (aIRR) of PCC compared to males. Active duty service members aged 55-64 had the greatest risk with an aIRR of 28.81 (95% CI, 20.81-38.75) compared to ADSM aged 17-24. The highest frequency co-occurring diagnoses were respiratory signs and symptoms, with 874 diagnosed with R06.02 (shortness of breath). Conclusion: Post–COVID-19 Condition represents a significant burden on the health of ADSM. Further research is warranted to study trends of PCC among the ADSM and to assess the effect of PCC on readiness and retention.