Effect of COVID-19 vaccine on long-COVID: A 2-year follow-up observational study from hospitals in north India

IntroductionLong-COVID syndrome encompasses a constellation of fluctuating, overlapping systemic symptoms after COVID. We know that vaccination reduces the risk of hospitalization and death but not of re-infections. How these vaccines impact long-COVID is under debate. The current study was designed to analyze the patterns of long-COVID amongst vaccinated and unvaccinated hospitalized patients during the three waves in India. MethodsThe computerized medical records of the patients admitted to a group of hospitals in the National Capital Region of Delhi with a nasopharyngeal swab positive RT-PCR for SARS-CoV-2, during the three distinct COVID-19 waves, were accessed. Because of large numbers, every 3rd case from the data sheet for the wave-1 and wave-2 but all cases admitted during wave-3 were included because of small numbers (total 6676). The selected patients were telephonically contacted in April 2022 for symptoms and their duration of long-COVID and their vaccination status. Of these, 6056 (90.7%) responded. These were divided into fully vaccinated who received both doses of COVID vaccine at least 14 days before admission (913) and unvaccinated at the time of admission (4616). Others and deaths were excluded. "Symptom-weeks" was calculated as the sum of weeks of symptoms in case of two or more symptoms. The statistical significance was tested, and odds ratio (unadjusted and adjusted) were calculated by logistic regression. ResultsNearly 90% of COVID-19 patients reported at least one symptom irrespective of their vaccination status. Almost three-fourths of these had symptoms lasting up to a month but nearly 15% reported a duration a least 4 weeks including 11% even exceeding one year. During wave-3, significantly more vaccinated patients reported short term post-acute sequelae of COVID-19 than did the unvaccinated group. The cases with diabetes and hypertension had higher odds of reporting at least one symptom when the effect of vaccination, age, sex, severity, and length of stay was adjusted. The fully vaccinated cases had reduced length of stay in the hospital and had a milder disease. Most common symptoms reported by both the groups were fatigue (17.0%), insomnia (15.1%) and myalgia (15%). There were significant differences in the duration and the type of long-COVID symptoms across the three waves, and the presence of comorbidities between the vaccinated and the unvaccinated groups but overall no difference could be detected. No significant difference was seen between the cases receiving covishield and covaxin. ConclusionsNearly 15% reported symptoms of duration exceeding 4 weeks including 11% exceeding one year. There were significant differences in the specific symptoms with some more common in the vaccinated and some others more common in the unvaccinated but overall the vaccination or the type of vaccine did not significantly alter either the incidence or the duration of long COVID.