Effect of COVID Vaccine on Long COVID: An Observational Study on Hospitalised Patients in North India

We know that vaccination reduces the risk of hospitalisation and death but how these vaccines impact long-COVID is under debate. The current study analyses the patterns of long-COVID amongst vaccinated and unvaccinated hospitalised patients during the three waves in India. From the computerised medical records of COVID patients admitted to a group of hospitals in and around Delhi every 3rd case of wave-1 and wave-2 and all cases of wave-3 were telephonically contacted in April 2022 for symptoms and their duration of long-COVID and their vaccination status. Of the 6676 contacted, 6056 (90.7%) responded. These were compared for two groups: fully vaccinated (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 fully vaccinated cases had reduced length of stay in the hospital and had a milder disease. When all the cases are combined, almost three-fourths had symptoms lasting up to a month. In the first two waves, 15.6% (95% CI: 14.6%–16.7%) reported a duration of exceeding 4 weeks including 11.5% (95% CI: 10.6%–12.4%) even one year or more. During wave-3, more vaccinated patients reported short-term long-COVID than the unvaccinated group. The cases with diabetes (OR = 1.96, 95% CI: 1.45–2.66) and hypertension (OR = 1.60, 95% CI: 1.25–2.04) had higher odds of reporting at least one symptom when the effect of vaccination, age, sex, severity and length of stay was adjusted. Most common symptoms reported by both the groups were fatigue, insomnia and myalgia. There were differences in the duration and the type of long-COVID symptoms between the vaccinated and the unvaccinated groups but overall, no difference could be detected. Nearly 15% reported symptoms of duration at least 4 weeks including 11% at last one year. Some symptoms were more common in the vaccinated and some others more common in the unvaccinated but overall, the vaccination did not alter either the incidence or the duration of long-COVID.