key: cord-0721901-rwm0utwt
authors: ruban, A. c. p.; Mohamed, A.; Kalyanaraman, S.
title: Effectiveness of vaccination in preventing severe SARS CoV-2 infection in South India-a hospital based cross sectional study
date: 2021-09-21
journal: nan
DOI: 10.1101/2021.09.17.21263670
sha: 8e32595dcda37448c03be8e79b858d6add4401cb
doc_id: 721901
cord_uid: rwm0utwt

Background & objectives: Establishing concrete evidence on effect of vaccination on severity of SARS CoV-2 infections in real world situations is the need of the hour. The aim of this study is to estimate the effectiveness Covid 19 vaccines in preventing the new and severe SARS CoV-2 infections. Methods: We did this retrospective cross-sectional study among the 4765 patients consecutive adult inpatients admitted in the Covid 19 wards of a tertiary care hospital from May 1,2021 to July 7, 2021 during the second wave of Covid 19 pandemic. Information on basic demographic variables, RT PCR status, vaccination status, outcome and clinical severity of illness were obtained from the electronic hospital patient records. Results, and Interpretation & conclusions: Type of vaccine and number of doses of vaccines didnot have any protective effect against new SARS CoV-2 infection. Covid 19 patients vaccinated with at least one dose had 75 % less risk of requiring oxygen (OR 0.25 CI: 0.15 to 0.44) and 60 % less risk of ICU admission (OR 0.4 CI: 0.2 to 0.6) and it was statistically significant. Only 31 % of fully vaccinated Covid 19 positive patients had oxygen requirement (90% less risk) and 15% of the fully vaccinated patients had needed ICU admission (90% less risk). Conclusion: Vaccination didnot protect against SARS Cov-2 infection however significant protection was documented against severe SARS Cov-2 infection. Vaccination coverage should be increased urgently in order to halt the impending wave of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

Damage caused by the Novel SARS-CoV-2 virus on global health is indescribable (1) . As of August 9 th of 2021, globally 20,22,96,216 people were affected and 42,88,134 deaths were caused by SARS CoV-2(2). Vaccination drive is one of the most imperative strategies ratified to combat the deadly pandemic.

Eradication of the Covid19 may be too aspirational a goal given the current situation; elimination of Covid 19 is still a realistic goal. Israel has achieved an all-time low level of infections of SARS-CoV-2 with high vaccination coverage (3) . India being the pharmaceutical hub; there are 8 vaccines in the pipeline under various phases of the clinical trial, 2 vaccines -Covishield and Covaxin were approved for restricted emergency use by the Drugs Controller General of India (DCGI) (4) . Covishield, produced by Serum Institute of India in synergy with Oxford University and Pharmaceutical giant Astra Zeneca uses a nonreplicating adenovirus viral vector that infects chimpanzees given in 2 doses 84 days apart. The efficacy of the vaccine was found to be 76% after the first dose. If the interval between the first and second dose was extended to 12 weeks or more the efficacy rose to 91.6% (5) . Covaxin, a domestic vaccine developed in the country by Bharat Biotech in collaboration with the Indian Institute of Medical Research (ICMR) and subsidiary National Institute of Virology (assisted by isolating virus sample) is an inactivated vaccine given 28 days apart with a vaccine efficacy of 81% (6) . is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint

The copyright holder for this this version posted September 21, 2021. ; https://doi.org/10.1101/2021.09.17.21263670 doi: medRxiv preprint the comorbid status were included in the vaccination drive from 1 April 2021. Vaccination for 18-44 years was kicked off from 1 May 2021 (7) .

Vaccine efficacy is defined as reduced risk of infection or disease among vaccinated individuals resulting from vaccination in carefully controlled circumstances; estimated from randomized clinical trials.

Vaccine effectiveness is reduced risk of infection or disease among vaccinated individuals attributed to vaccination in real-world conditions; estimated from observational (non-randomized) studies. Gauging COVID-19 vaccine performance in the real world is crucial. Several factors like cold chain management during transportation and storage, completing dosing schedule, the inclusion of the general population (as people enrolled in a clinical trial are many times young and healthy) has a bearing on real-world vaccine effectiveness (8) . Vaccine hesitancy is one of the top ten global health threats reported by the World health organization which threatens the progress made against vaccine-preventable diseases(9). In Tamil Nadu, only 5.9% of the people were fully vaccinated and 26% of the people had received at least one dose of vaccination which is below the national average ( 8.1% and 28.6% respectively)(10). With high vaccine hesitancy among the population, providing concrete evidence on the effect of vaccination on the severity of the disease has become crucial and need of the hour. Hence this study was mapped out to analyse vaccine effectiveness in preventing severe SARS CoV-2 infection as there is a significant dearth of such studies in our country to arrive at a decisive policy on vaccination.

. CC-BY-NC-ND 4.0 International license It is made available under a perpetuity.

is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint 

Antenatal mothers and children (aged <13 years) were excluded from the study population as vaccination for them wasn't started yet.

Patients with incomplete data on outcome measured were excluded from the study. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint We did this retrospective cross-sectional study among the consecutive adult inpatients admitted in the Covid 19 wards of a tertiary care hospital, South India in the above said period. Our hospital is a government-run medical college hospital. It offers speciality and super speciality and allied health services and caters also to the neighbouring districts. All the patients admitted are tested for SARS-COV2 infection via nasopharyngeal and oropharyngeal swabs and the samples are transported to the designated Microbiological Lab within the College campus and the turnover time for report generation is within 12

hours.

An Electronic patient record database (Google sheet) has been developed and maintained by the hospital Covid control room and the required study variables were extracted from the database. After getting approval from the Institutional ethics committee, the following variables were collected; Name, age, sex, Clinical guidelines for the management of Covid 19 issued by the Ministry of Health and family welfare, Government of India was followed for disease classification as follows: (11) . is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint Vaccine breakthrough infection is defined as the detection of SARS-CoV-2 RNA or antigen in a respiratory specimen collected from a person ≥14 days after they have completed all recommended doses of COVID-19 vaccine (12) .

The proportion of patients with severe Covid 19 (patients require oxygen; patients requiring ICU admission, the proportion of patients died).

The proportion of patients with severe Covid 19 (patients requiring oxygen; patients requiring ICU admission, the proportion of patients died) following vaccination

Data entry was done with Microsoft Excel and data analysis was done with SPSS 23 Version. Frequencies and proportions were calculated as appropriate. Means, Range and standard deviation were calculated for quantitative variables. The difference between the proportions was calculated using the Chi-Square test.

Differences between more than two proportions were calculated using the Chi-Square trends.

A total of 4765 patients have been admitted in Covid 19 wards during the above said period. After excluding the antenatal mothers and children (353) and patients with incomplete data about the outcome studied (734), a total of 3679 patients were included in this study. The majority of the patients were male (60%). The majority of the patients belonged to the age group of 61-70 years (27.2%) followed by the 51-60 years is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint

The copyright holder for this this version posted September 21, 2021. ; https://doi.org/10.1101/2021.09.17.21263670 doi: medRxiv preprint (26.2%) age group. The mean age of the study population was 56.8 years and the standard deviation was 14.2. (Table 1) 95% of the patients were symptomatic and 53 % of the patients had co-morbid conditions. Among the patients presented with SARI (Severe acute respiratory illness), 44% were RT-PCR positive. Among the SARI cases, 65% of the patients needed ICU care on admission. The proportion of SARI patients admitted post-Covid vaccination was 3.7%. The proportion of patients with SARI who needed oxygen was 80.6% and the Proportion of patients with SARI who needed ICU admission was 65%. The proportion of patients who died during the hospital stay was 23.4%. The proportion of patients with RT-PCR positive needed oxygen was 78.5% and the Proportion of patients with RT-PCR positive needed ICU admission was 63%.

The proportion of patients who died during the hospital stay was 29.5% (Table 1) .

Our study didn't find any protective effect of vaccination against new COVID 19 infections. Type of vaccine nor number of doses has any effect on new infection. Those who had prior vaccination have 1.2 times more odds of becoming positive with RT PCR when compared to patients who didn't have vaccination; however, it is not statistically significant(p>0.05). More samples are needed to conclude further. Out of the 21 patients who had more than 2 doses of vaccines, the data on days between the second dose of vaccination and date of RT PCR positive was available for 16 patients. 7 of them (43.8%) had a breakthrough infection (RT PCR positive after 14 days of vaccination). (Table 3 )

Those aged more than 59 years (1.7 times) and patients without co-morbidity (1.5 times) have higher odds of requiring oxygen therapy and it was statistically significant(p<0.05). There was no significant difference exists between the two groups in terms of sex and residence. (Table 2) . CC-BY-NC-ND 4.0 International license It is made available under a perpetuity.

is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint and 80% reduction in the need for oxygen therapy respectively when compared to patients without vaccination. both of them were statistically significant(p<0.05). RTPCR positive patients with at least one dose of Covid 19 vaccine and full vaccinated RTPCR positive patients had 75% and 90% reduction in the need for oxygen therapy respectively when compared to patients with RT PCR negative and it was statistically significant (p<0.05). Both were statistically significant(p<0.05). (Table 4 )

Females (1.2 times), those aged more than 59 years (1.5 times) and patients without co-morbidity (1.4 times) have higher odds of needing ICU care on admission and it was statistically significant(p<0.05). (Table 2) SARI patients with at least one dose of Covid 19 vaccine and fully vaccinated SARI patients had a 50% and 70% reduction in the need for ICU admission respectively when compared to patients without vaccination. both of them were statistically significant(p<0.05). RTPCR positive patients with at least one dose of Covid 19 vaccine and full vaccinated RTPCR positive patients had a 60% and 90% reduction in the need for oxygen therapy respectively when compared to patients with RT PCR negative and it was statistically significant (p<0.05). Both were statistically significant(p<0.05). (Table 4 )

Those aged more than 59 years (1.6 times) and patients with co-morbidity (1.2 times) had more odds of dying and it was statistically significant(p<0.05) ( Table 2) .

SARI patients with at least one dose of Covid 19 vaccine and fully vaccinated SARI patients had a 20% and 85% reduction in the need for ICU admission respectively when compared to patients without vaccination. however, both were not statistically significant(p>0.05). RTPCR positive patients with at least is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint

The copyright holder for this this version posted September 21, 2021. ; https://doi.org/10.1101/2021.09.17.21263670 doi: medRxiv preprint one dose of Covid 19 vaccine and full vaccinated RTPCR positive patients had a 20% and 80% reduction in the need for oxygen therapy respectively when compared to patients with RT PCR negative and it was statistically significant (p<0.05 however, both of them were not statistically significant(p>0.05). (Table 4 ).

We did this retrospective cross-sectional study among the patients admitted in the Covid 19 wards of a tertiary care hospital during the second wave of the Covid 19 pandemic. In our study, only 3.8% of SARI patients and 4% of the RTPCR positive patients were vaccinated which is comparable to the district data as well as the state vaccine coverage (10) . There is a possibility that vaccination could have reduced the need for hospitalization which needs to be explored. The proportion of SARI patients and RT PCR positive patients who required oxygen support, ICU admission and died reported by our study was significantly higher than the first wave studies and also other studies done during the second wave in India. Our study had found that 80% of patients with SARI and 79 % of the RT PCR positive patients required oxygen. 65% of the SARI patients and 63% of the RT PCR is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint findings. This is in contrast to the finding that only 5-15% percentage of the patients had the severe disease as reported by the first wave study findings (15) (16) (17) (18) (19) (20) . More transmission and more virulence were noticed in the second wave which suggests that this could be due to different virus strains (21) . Another important reason for the high proportion of patients with severe disease could be the hospital admission policy.

Only 31 % of fully vaccinated Covid 19 positive patients had oxygen requirement (90% less risk of requiring oxygen during admission) and 15% of the fully vaccinated patients had needed ICU admission (90 % less risk of ICU admission) as compared to non-vaccinated people (78%, 62% respectively) and it was significant. Only 7.7% (n=1) of the fully vaccinated covid 19 positive patients had died; 80 % less risk of death as compared to non-vaccinated people (30%) and however it was not significant. More number of samples are needed to conclude further. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint protection against hospitalization and symptomatic infections(28). The efficacy of the covishield vaccine against symptomatic infections was found to be 76% after the first dose. If the interval between the first and second dose was extended to 12 weeks or more the efficacy rose to 91.6% (5) . Not many studies are available in India in this category to make more comparisons. Our study findings are comparable to other studies however the protective effect documented by them was higher than ours. A possible reason would be the smaller number of vaccinated (n=94) and fully vaccinated patients(n=21) in our study. The inclusion of a greater number of vaccinated people may give more evidence. There is a paucity of studies in this field and more samples are needed to conclude further.

The proportion of vaccinated and fully vaccinated patients were low in our study. Explicit research with more sample size and negative case-control study is quintessential to corroborate the findings. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint

The copyright holder for this this version posted September 21, 2021. ; https://doi.org/10.1101/2021.09.17.21263670 doi: medRxiv preprint Tables: is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint

The copyright holder for this this version posted September 21, 2021. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint

The copyright holder for this this version posted September 21, 2021. ; https://doi.org/10.1101/2021.09.17.21263670 doi: medRxiv preprint

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