Clinical outcomes in vaccinated individuals hospitalized with Delta variant of SARS-CoV-2

Abstract

Emerging variants of SARS-CoV-2 with increased transmissibility or immune escape have been causing large outbreaks of COVID-19 infections across the world. As most of the vaccines currently in use have been derived from viral strains circulating in the early part of the pandemic, it becomes imperative to constantly assess the efficacy of these vaccines against emerging variants. In this hospital-based cohort study, we analysed clinical profiles and outcomes of 1161 COVID-19 hospitalized patients (vaccinated with COVISHIELD (ChAdOx1) or COVAXIN (BBV-152), n = 495 and unvaccinated n = 666) in Hyderabad, India between April 24th and May 31st 2021. Viral genome sequencing revealed that >90% of patients in both groups were harbouring the Delta variant (Pango lineage B.1.617.2) of SARS-CoV-2. Vaccinated individuals showed higher neutralizing antibodies (545+-1256 AU/ml Vs 51.1+-296 AU/ml; p<0.001) and significantly decreased Ferritin (392.26+-448.4 ng/mL Vs 544.82+-641.41 ng/mL; p<0.001) and LDH (559.45+-324.05 U/L Vs 644.99+- 294.03 U/L; p<0.001), when compared to the unvaccinated group. Severity of the disease (3.2% Vs 7.2%; p=0.0039) and requirement of ventilatory support (2.8% Vs 5.9%; p=0.0154) were significantly low in the vaccinated group despite the fact that these individuals had significantly higher age and risk factors. The rate of mortality was about 50% lower (2/132=1.51%) in the completely vaccinated breakthrough infections although mortality in individuals who had received a single dose was similar to the unvaccinated group (9/269=3.35% vs 23/666= 3.45%). Our results demonstrate that both COVISHIELD and COVAXIN are effective in preventing disease severity and mortality against the Delta variant in completely vaccinated hospitalized patients.

Comparison of the Clinical and Laboratory Findings and Outcomes of Hospitalized COVID-19 Patients Who Were Either Fully Vaccinated with Coronavac or Not: An Analytical, Cross Sectional Study

“…Indeed, comorbidities were found as independent risk factors for mortality in the multivariate analysis, while vaccination was not. In contrast to our study, the severity of the disease and a requirement for ventilator support were significantly lower in the vaccinated group than in the unvaccinated patients in the Indian study mentioned above; however, the mortality rate was not found to be significantly different between the groups in that study and, similar to our study, no significant differences were seen in the incidence of acute kidney injury, requirement for renal replacement therapy or thrombotic complications between the two groups [ 12 ]. In another study of 218 mRNA-vaccinated breakthrough delta variant COVID-19 cases hospitalized in a Singapore Hospital, despite the significantly older age of the vaccine breakthrough group, the odds of severe COVID-19 requiring oxygen supplementation were significantly lower following vaccination, and vaccination was found to be associated with a faster decline in viral RNA load and a robust serological response [ 14 ].…”

“…Finally, in a recent study from the USA, among patients hospitalized with COVID-19, mRNA vaccine breakthrough cases less commonly received ICU care and invasive mechanical ventilation than unvaccinated cases, and the likelihood of death was also lower in the vaccinated cases; but these findings did not differ by age group or immunocompromised status [ 11 ]. These differences in the clinical severity and outcomes of vaccinated and unvaccinated hospitalized COVID-19 patients between our study and other cohorts might be associated with two reasons: One is that compared with the Indian and Singapore cohorts [ 12 , 14 ], our and USA’s [ 3 ] vaccinated breakthrough cases were older (mean ages were 75 and 73 vs. 58 and 56 years in our and USA and Indian and Singapore studies, respectively) and had more comorbidities (prevalence of HT+ DM were 72% + 44% and 70% + 39% vs. 51% vs. 7% + 19% in our and USA [ 3 ] and Indian and Singapore cohort [ 12 , 14 ], respectively). Both older age and comorbidities are well-defined risk factors leading to severe disease and lower antibody response and protection from vaccines or higher vaccine unresponsiveness.…”

“…Additionally, the laboratory findings on admission of vaccinated patients were similar to the findings of unvaccinated COVID-19 patients in our cohort, except that the mean ferritin level of vaccinated patients was lower than the levels in unvaccinated patients (690.04 ng/mL vs. 485.42 ng/mL). In another study from India, ferritin levels were also found to be lower in patients with vaccine breakthrough infections than in patients with primary infection (544.82 ng/mL vs. 392.26 ng/mL) [ 12 ]; however, no significant differences were found in white blood count, absolute lymphocyte count nadir, CRP, interleukin-6, procalcitonin, oxygen saturation, lung involvement, and fever frequency between the recipients of the first and second vaccine doses in a study conducted in Poland [ 13 ]. It should be known that the clinical course or laboratory findings of patients hospitalized due to breakthrough COVID-19 after Coronavac vaccination may not reveal any distinctive features.…”

“…Although the mean S/CO of anti-S IgG on the 7th day of complaints among Coronavac-vaccinated inpatients was higher than that among unvaccinated inpatients in our study, the numbers were found to be very close to one another, at 6.11 vs. 5.14, respectively. However, it was shown that SARS-CoV-2 breakthrough infections are a strong booster of the humoral immune response among fully vaccinated patients, the anti-spike IgG antibody levels were increased significantly as low as 2 to 4 days after the onset of symptoms of breakthrough infections, and the levels were more than 10-fold higher in fully vaccinated infected individuals than in unvaccinated uninfected individuals [ 12 , 27 , 28 ]. These findings also support the lower response rate to the Coronavac vaccine in our cohort.…”

Current Review of Delta Variant of SARS-CoV-2

“…Kumar et al [30] investigated the clinical outcomes of vaccinated persons among hospitalized patients in India. They examined the clinical attributes and consequences of 1161 hospitalized patients of COVID-19.…”