Impact of COVID-19 vaccination on disease severity & outcomes in hospitalized patients in a tertiary care centre in the second wave

Sir,

COVID-19 vaccination has been shown to reduce disease severity12, but there are scant reports of outcomes in vaccinated hospitalized patients with COVID-19 pneumonia in India. We present here the outcomes in vaccinated patients with COVID-19 pneumonia in the second wave hospitalized in Apollo Hospital, a tertiary care center, Bengaluru, India. The characteristics of the patients were as follows; 500 consecutive patients with moderate-to-severe COVID-19 pneumonia were admitted over 40 days between April 21 and May 30, 2021; of these 320 (64%) were males and the mean age was 52.5±15.8 yr. The mean body mass index (BMI) was 26.6±4.8 kg/m²; 256 (51.2%) patients had at least one comorbidity; 37.5 and 30.5 per cent of patients had diabetes mellitus and hypertension, respectively. While all patients had an increased C-reactive protein (CRP) level, mean CRP level at admission was 70.8±31.2 mg/dl. On admission, 265 (53%) patients required respiratory support ranging from low-flow oxygen to mechanical ventilation. In the remaining 235 patients without respiratory support at admission, 85 (36%) patients worsened clinically and eventually required respiratory support during the course of hospitalization. The overall mortality rate was 17.2 per cent, with a median length of hospital stay of six days.

Of the 500 patients, 148 (29.6%) were vaccinated with at least one dose of COVID-19 vaccine before being hospitalized; of these, 14 (9.5%) had received both doses. The majority of vaccinated patients [124 (84%)] received the ChAdOx1 nCoV-19 coronavirus vaccine (Covishield), while 24 (16%) received BBV152 (Covaxin). The median time from the first dose to hospitalization was 25 days (1-150 days) and second dose to admission was 18 days (2-51 days).

Data was tabulated and analysed using SPSS version 25.0 (IBM Corp. Chicago, IL, USA). Results were analysed in a descriptive fashion as numbers and percentages, mean and standard deviation, median and inter quartile range (IQR). Difference between mean and median was expressed using chi-square test and Mann-Whitney U test, respectively. Correlation analysis was performed using linear correlation and results expressed using Pearson’s correlation coefficient. P<0.05 was considered as significant.

The mean age of vaccinated patients (VPs) was 58.4±13.6 yr compared to 49.9±16 yr in non-vaccinated patients (NVPs) (P<0.05). Assessing disease severity, 29 of 148 (19.6%) VPs compared to 125 of 352 (35.5%) NVPs had severe disease at presentation (P<0.05). This was also reflected in the laboratory parameters, with VPs having a significantly lower CRP level at baseline (74.2 vs. 64.5 mg/dl, P<0.05). In terms of respiratory support, 66 (44.5%) VPs required respiratory support at baseline, compared to 199 (56.5%) of NVPs (P<0.05). Of note, the need for respiratory support was lower in VPs despite a higher mean age as noted above (58.4±13.6 yr) and more comorbidities (71 vs. 53%, P<0.05). Of the 352 NVPs, 170 (48%) had worsening hypoxia during hospitalization as compared to only 51 of 148 (34.5%) patients in the VP group (P<0.05). The overall mortality was numerically lower in the VP group (VP 13.5% vs. 18.75% NVP), though statistically not significant. The cause for mortality in all cases was severe COVID-19 pneumonia and acute respiratory distress syndrome (ARDS). The subgroup analysis between VP and NVP groups is presented in the Table.

All the 20 of 148 (13.5%) VPs who died had received a single dose of vaccine. All patients who received two doses (14/148, 9.5%) were discharged from the hospital. The VPs who died had a higher mean CRP (113 vs. 56.3 mg/dl, P<0.05) as compared to survivors and were on respiratory support at admission.

The analysis of data focusing on outcomes in vaccinated hospitalized COVID-19 patients, showed that vaccination with both vaccines had a significant impact on reducing severity of disease, inflammatory markers, need for respiratory support and a trend towards lower mortality. This effect was seen despite the VPs having more risk factors such as higher mean age and comorbidities. Similar results were noted in studies from Europe, Israel and Brazil23. The data published by the Ministry of Health and Family Welfare, Government of India, suggest that vaccines effectiveness in preventing death after the first dose is 96.6 per cent and after two doses is 97.5 per cent4. The impact of single dose versus two doses could not be evaluated, as most of these patients (134/148, 90.5%) were vaccinated with only a single dose. There was no mortality in the VPs who received two doses, but this finding could not be confirmed with a large number of patients. This remains the main lacunae of the study.

In conclusion, our study suggests the role of vaccination in impacting disease severity despite hospitalization for COVID-19 pneumonia. It raises additional questions on outcomes such as mortality and the role of one versus two vaccine dose(s).