Vaccination against COVID-19 may reduce the risk of , with a rate of 0.81 for those vaccinated compared to unvaccinated.
Among 35,713 vaccinated patients and 75,522 unvaccinated patients, the incidence rate ratio (IRR) for long COVID was 0.81 overall.
In immunocompetent patients, the IRR for long COVID was 0.83, while in immunocompromised patients, it was 0.28.
No link was found between vaccination status and the number of primary care visits for patients with long COVID.
Costs for primary care consultations were higher for unvaccinated patients than for those who completed their vaccination series.
Future research may provide clearer insights into the effects of vaccination on long COVID over larger populations and longer timeframes.
Simplified
BACKGROUND: , a diverse set of symptoms that persist after a minimum of 4 weeks from the initial SARS-CoV-2 infection, has posed substantial burden to healthcare systems. There is some evidence that COVID-19 vaccination may be associated with lower risk of long COVID. However, little is known about the association between vaccination status and long COVID-associated healthcare resource utilisation (HCRU) and costs.
METHODS: We conducted a cohort study using primary care electronic health record data in England from the Clinical Practice Research Datalink (CPRD) Aurum dataset linked to Hospital Episode Statistics where available. Adult (≥ 18 years) patients were indexed on a COVID-19 diagnosis between 1st March 2021 and 1st December 2021. Vaccination status was assessed at index: unvaccinated or completed primary series (two doses for immunocompetent and three doses for immunocompromised patients). Covariate balance was conducted using entropy balancing. Weighted multivariable Poisson regression was used to estimate the incidence rate ratio (IRR) for incident long COVID, and separately long COVID primary care resource use, by vaccination status. Patients were followed up to a maximum of 9-months post index.
RESULTS: A total of 35,713 patients who had completed primary series vaccination, and 75,522 unvaccinated patients were included. The weighted and adjusted IRR for long COVID among patients vaccinated with the primary series compared to being unvaccinated was 0.81 (95% CI: 0.77-0.86) in the overall cohort, 0.83 (95% CI: 0.78-0.88) in the immunocompetent cohort and 0.28 (95% CI: 0.13-0.58) in the immunocompromised cohort. Among those with long COVID, there was no association between the rate of primary care consultations and vaccination status in the overall and immunocompetent cohorts. Cost of primary care consultations was greater in the unvaccinated group than for those who completed primary series.
CONCLUSION: Vaccination against COVID-19 may reduce the risk of long COVID in both immunocompetent and immunocompromised patients. However, no association was found between frequency of primary care visits and vaccination among patients diagnosed in 2021. Future studies with larger sample size, higher vaccine uptake, and longer study periods during the pandemic are needed to further quantify the impact of vaccination on long COVID.
Key numbers
0.81
Incidence Reduction
Adjusted incidence rate ratio for vaccinated vs. unvaccinated patients.
0.28
Immunocompromised Incidence Reduction
Adjusted incidence rate ratio for immunocompromised patients vaccinated vs. unvaccinated.
1.15
Primary Care Consultation Rate
Incidence rate ratio for primary care consultations among patients with clinical codes.
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Declarations. Ethics approval and consent to participate: The Clinical Practice Research Datalink’s (CPRD) supplies anonymised UK health data for public health research sponsored by the National Institute for Health Research (NIHR) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). The UK’s Health Research Authority Research Ethics Committee (East Midlands - Derby Research Ethics Committee) provides ethical approval to CPRD annually. No additional ethical approval is required for observational studies using CPRD Aurum data for public health research, subject to individual research protocols meeting CPRD data governance requirements. Therefore, informed consent is deemed unnecessary by CPRD. However, access to the CPRD database does require approval from CPRD’s Research Data Governance (RDG) committee; this study was approved by CPRD’s RDG: CPRD study ID: 22_002431, and therefore is covered by CPRD’s ethical approval. Consent for publication: Not applicable. Competing interests: This study was sponsored by Pfizer. JY, TA, LM, KMA, CT, RB, CR DM and JLN are employees of Pfizer and may hold stock or stock options. KKR, TT, LM and OM are employees of Adelphi Real World, which received funds from Pfizer to conduct the study and develop the manuscript. Funding: Funding for this study was provided by Pfizer Inc. The study protocol was developed collaboratively by Pfizer and Adelphi Real World. The protocol was independently reviewed and approved by CPRD’s Research Data Governance (RDG) committee, and the analysis was conducted by Adelphi Real World. Adelphi Real World wrote the first draft of the manuscript, and both Pfizer and Adelphi Real World reviewed and approved the manuscript prior to submission.
