Long COVID-19 symptoms can affect even fully vaccinated people after mild breakthrough infections, but their risk of serious complications such as lung and blood-clotting disorders is much lower than that of their unvaccinated peers, finds a study of more than 13 million US veterans published this week in Nature Medicine.Researchers from Washington University and the VA Saint Louis Health Care System extracted data from US Department of Veterans Affairs (VA) databases on 33,940 veterans who had mild COVID-19 from Jan 1 to Oct 31, 2021, after receiving two doses of the Pfizer/BioNTech or Moderna vaccines or one dose of the Johnson & Johnson vaccine.They were compared with 4,983,491 contemporary unvaccinated and uninfected controls, 5,785,273 historical controls, and 2,566,369 vaccinated controls.
The study period preceded the emergence of the Omicron variant.Veterans diagnosed as having COVID-19 were mostly older, White men, but the study also included more than 1.3 million women and adults of all ages and races.Most protective against lung disorders, blood clotsRelative to the 113,474 infected, unvaccinated veterans, those who were vaccinated and then infected were at lower risk for death (hazard ratio [HR], 0.66; 95% CI, 0.58 to 0.74) and long-term symptoms (HR, 0.85; 95% confidence interval [CI], 0.82 to 0.89).The risk of long COVID was 17% higher among vaccinated, immunocompromised people who later tested positive for COVID-19, relative to healthy, vaccinated, infected veterans.
An analysis of 3,667 vaccinated veterans hospitalized for their infections found that they were at 2.5 times the risk for death and a 27% higher risk of long COVID within 30 days of symptom onset than 14,337 peers hospitalized with the flu."Va