Association of COVID vaccinations and treatments with long COVID beyond 6 months: a case-control study on the adult population in a large integrated healthcare system in the United States from 2020 to 2023.

OBJECTIVE

Long coronavirus disease (Long COVID) is a chronic condition causing significant long-term disability and economic burden. This study aims to measure the association between COVID vaccinations and treatment at the time of acute infection with Long COVID outcomes beyond six months post-infection, controlling for demographic and medical variables.

METHODS

This retrospective case-control study used electronic medical records from Kaiser Permanente Southern California to evaluate Long COVID outcomes from January 2022 to June 2023 with vaccination doses and nirmatrelvir/ritonavir, and from October 2020 to June 2023 with remdesivir and other treatments. Statistical analysis used univariate chi-square and Kruskal-Wallis tests and conditional logistic regression.

RESULTS

Our study had 840 (January 2022 analysis) and 2632 (October 2020 analysis) Long COVID patients diagnosed by International Classification of Diseases-10 code at least 6 months after acute COVID infection with 1:5 matched controls by age, sex, race/ethnicity, Body Mass Index, and date of acute COVID infection. Long COVID outcome was inversely associated with the number of COVID vaccination doses (one dose odds ratio (OR) 0.77; 95 % CI 0.63-0.96, two doses OR 0.73; 95 % CI 0.59-0.92, three doses OR 0.64; 95 % CI 0.44-1.00, four doses OR 0.29; 95 % CI 0.06-1.49) and nirmatrelvir/ritonavir (OR 0.05; 95 % CI 0.04-0.07) or remdesivir (OR 0.31; 95 % CI 0.19-0.49) treatment with no interaction between three vaccinations with nirmatrelvir/ritonavir and four vaccinations with remdesivir treatment.

CONCLUSION

These findings may influence existing clinical practices for vaccination and antiviral treatment strategies to decrease Long COVID consequences.