Vaccinated patients fared better across outcomes
At 4 weeks after infection, 41% of fully vaccinated patients had at least one persistent symptom, compared with 54% of unvaccinated or partially vaccinated patients (P = .04). At 3 months after infection, 21% of fully vaccinated patients had at least one persistent symptom, compared with 41% of unvaccinated or partially vaccinated patients (P < .0001).
Vaccinated patients were half as likely to have long COVID at 4 weeks after infection (adjusted odds ratio, 0.49) and 90% less likely to have long COVID 3 months after infection (aOR, 0.1), after adjustment for age, sex, race, comorbidities, and use of any of four immune-suppressing medications (anti-CD20 monoclonal antibodies, methotrexate, mycophenolate, or glucocorticoids).
Fully vaccinated patients with breakthrough infections had an average 21 additional days without symptoms during follow-up, compared with unvaccinated and partially vaccinated patients (P = .04).
Reduced risk of long COVID did not change for vaccinated patients after sensitivity analyses for those who did not receive nirmatrelvir/ritonavir (Paxlovid) or monoclonal antibodies, those who didn’t receive any COVID-19-related treatment, those who completed their questionnaires within 6 months after infection, and those who were not hospitalized.
“One important message is that among those who did get PASC, the severity appears similar among those with and without a breakthrough infection,” Dr. Wallace said. “This highlights the need for ongoing research to improve recognition, diagnosis, and treatment of PASC.”
Many more breakthrough infections (72%) than nonbreakthrough infections (2%) occurred during Omicron. The authors acknowledged that different variants might play a role in different long COVID risks but said such potential confounding is unlikely to fully explain the results.
Dr. Naomi Patel
“Even with data suggesting that the Omicron variants may be intrinsically less severe, vaccination still has an impact on severity of infection, rates of hospitalization, and other outcomes and thus may play a role in the risk of PASC,” lead author Naomi Patel, MD, an instructor at Harvard Medical School and a rheumatologist at Massachusetts General Hospital, said in an interview. “A study evaluating the proportions with PASC by vaccination status during the time in which a single variant is predominant, such as the early Omicron era, could help to better assess the more isolated impact of vaccination on PASC.”
Dr. Calabrese said he is convinced that Omicron infections are less likely to result in more severe forms of acute COVID than pre-Omicron infections, and he suspects Omicron infections are also less likely to result in long COVID, although less evidence currently supports this hypothesis.
Dr. Leonard Calabrese
Hospitalization was more common in unvaccinated/partly vaccinated patients than in vaccinated patients (27% vs. 5%; P = .001). Although pain and fatigue were lower in those with breakthrough infections, functional scores and health-related quality of life were similar in both groups.
Some symptoms significantly differed between vaccinated and unvaccinated/partly vaccinated groups, possibly caused partly by different variants. Nasal congestion was more common (73%) in those with breakthrough infections than in those with nonbreakthrough infections (46%; P < .0001). Those who were unvaccinated/partly vaccinated were significantly more likely to have loss of smell (46% vs. 22%) or taste (45% vs. 28%) or to have joint pain (11% vs. 4%).
Treatment with nirmatrelvir/ritonavir was also more common in vaccinated patients (12%) than in unvaccinated/partly vaccinated patients (1%; P < .0001), as was treatment with monoclonal antibodies (34% vs. 8%; P < .0001).
Dr. Jeffrey A. Sparks
The study was limited by its low diversity and being at a single health care system, the authors said. Study coauthor Jeffrey A. Sparks, MD, MMSc, an assistant professor of medicine at Brigham and Women’s Hospital and Harvard Medical School, said in an interview that the group is planning additional studies as their cohort grows, including “investigating the relationships between COVID-19 and specific rheumatic diseases and immunomodulating medications, expansion of autoimmunity and systemic inflammation, and lung damage among specific patient populations.”
Dr. Calabrese said it will be important for follow-up study of the symptomatic patients to “determine how many of these patients will fit the clinical picture of long COVID or long-haul phenotypes over the months and years ahead, including documenting exertional malaise and quality of life.
This study only assessed patients who received zero, one, or two doses of a vaccine, but many patients with rheumatic disease today will likely have received booster doses. However, Dr. Calabrese said it would be difficult to quantify whether a third, fourth, or fifth dose offers additional protection from long-term COVID complications after full vaccination or hybrid vaccination.
The research was funded by the Rheumatology Research Foundation, the National Institutes of Health, the R. Bruce and Joan M. Mickey Research Scholar Fund, and the Llura Gund Award for Rheumatoid Arthritis Research and Care. Dr. Wallace has received research support from Bristol-Myers Squibb and Principia/Sanofi and consulting fees from Zenas BioPharma, Horizon, Sanofi, Shionogi, Viela Bio, and Medpace. Dr. Sparks has received research support from Bristol-Myers Squibb and consulting fees from AbbVie, Amgen, Boehringer Ingelheim, Bristol-Myers Squibb, Gilead, Inova Diagnostics, Janssen, Optum, and Pfizer. Dr. Patel has received consulting fees from FVC Health. Calabrese has consulted for Genentech, Sanofi-Regeneron, AstraZeneca, and GlaxoSmithKline.
A version of this article first appeared on Medscape.com.