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At least one dose of vaccine before COVID-19 infection provided 60% protection against post-discharge mortality, an Indian Council of Medical Research (ICMR) study on factors related to mortality within one year after discharge in hospitalised COVID-19 patients has found. The study has also found that there is a higher chance of mortality within one year following discharge for those over 40 years of age, those with comorbidities, and those who suffered moderate to severe COVID-19. The study observed that of the 14,419 participants contacted at least once in one year after discharge from the hospital, 942 deaths or 6.5% all-cause mortality were reported. Overall, the study’s findings suggest that a post-discharge mortality rate of 6.5% in patients hospitalised for COVID-19 warrants a vigilant follow-up. “Encouragingly, vaccination before the COVID-19 infection confers protection to post-discharge mortality. Post-COVID Conditions (PCC) and the presence of comorbidities may have some association with late post-discharge deaths; further research is warranted in this field,” the study said. Similar trends were seen in participants in the 18-45 years age group. The study also noted that the National Clinical Registry for the COVID-19 study team had conducted matched nested case-control analyses to evaluate the factors related to one-year post-discharge mortality. 

The ICMR has been maintaining the National Clinical Registry for COVID-19 at 31 centres across the country, where all hospitalised COVID-19 patients are periodically contacted by telephone till one year after discharge. Data collected till February 2023 were included in the study. Meanwhile, other ongoing studies on COVID include the effect of the vaccine on thrombotic events in the 18-45-year-old population in India in 2022 and factors associated with sudden deaths in the same age bracket. The study further states that in the present investigation, post-COVID conditions were associated with 2.7 times higher odds of post-discharge mortality. The limitations of the current investigation include reliance on telephonic follow-up, which could have led to underreporting of the symptoms. The present analysis only included patients who were hospitalised due to COVID-19, and consequently, the findings cannot be generalised to all patients who had COVID-19. Furthermore, the operational definition of PCC used in this study is not an exact match to either the World Health Organization (WHO) or the definition of the Centers for Disease Control (CDC). This variation of the definition for PCC may be a source of bias. In the first two nested case-control analyses, it is possible that the participants could have died sometime after being contacted and were misclassified as controls rather than cases. “However, we do not expect any major bias to arise, as this misclassification would have made the analyses more conservative,’’ notes the study.