ABSTRACT
Globally 58.83% human population received at least one dose of the COVID-19 vaccines as of 5 January 2021. COVID-19 vaccination rollout is progressing at varied rates globally and data on the impact of mass vaccination on infection and case-fatality rates require definition. We compared the global reported cumulative case-fatality rate (rCFR) between top-20 countries with COVID-19 vaccination rates (>125 doses/100 people) and the rest of the world, before and after commencement of vaccination programmes. We considered the 28th day of receiving the first vaccine in the world as a cut-off to compare the pre-vaccine period (Jan 1, 2020 - Jan 5, 2021) and the post-vaccine period (Jan 6, 2021-Jan 5, 2022). We used a Generalized linear mixed model (GLMM) with a beta distribution to investigate the association between the CFR and potential predictors of each country and reported the relative risk (RR) of each variable. The mean rCFR of COVID-19 in the top-20 countries with vaccination rates was 1.83 (95% CI: 1.24-2.43) on 5 Jan 2021 and 1.18 (95% CI: 0.73-1.62) on 5 Jan 2022. The CFR for the rest of the world on 5 Jan 2021 was 2.32 (95% CI: 1.86-2.79) and 2.20 (95% CI: 1.86-2.55) on 5 January 2022. In Sub-Saharan Africa, the CFR remained roughly unchanged at 1.97 (95% CI: 1.59-2.35) on 5 Jan 2021 and 1.98 (95% CI:1.58-2.37) on 5 Jan 2022. The GLMM showed vaccination (/100 population) (RR:0.37) and Stringency Index (RR:0.88) were strong protective factors for the countrys COVID-19 CFR indicating that both vaccination and lockdown measures help in the reduction of COVID-19 CFR. The rCFR of COVID-19 continues to decline, although at a disproportionate rate between top vaccinated countries and the rest of the world. Vaccine equity and faster roll-out across the world is critically important in reducing COVID-19 transmission and CFR. Key Questions What is already knownO_LIVaccination can reduce the case-fatality rate of COVID-19. Globally, the COVID-19 vaccination rollout is progressing at varied rates. C_LI What are the new findingsO_LIIn the top-20 countries with vaccination, >200 doses of vaccines are given per 100 people on 5th Jan 2022, In the rest of the word, the figure is 105, and in Sub-Saharan Africa (SSA) only 15.72 C_LIO_LIAfter the introduction of COVID-19 vaccination the reported case-fatality rate (rCFR) of COVID-19 has reduced by 35% in the top-20 countries with vaccination, 8% in the rest of the world roughly unchanged in SSA. C_LIO_LIThe doses of COVID-19 vaccines (/100 people) and rCFR has a negative correlation on 5 Jan 2022 (r=-0.296, p<0.001). C_LIO_LIThe COVID-19 vaccination and Stringency Index are strong protective factors for the countrys COVID-19 rCFR indicating that both vaccination and lockdown measures help in reduction of COVID-19 rCFR. C_LI What do the new findings implyO_LIThe disproportionate case-fatality rate of COVID-19 between top vaccinated countries and the rest of the world demand fast and equitable vaccine rollout globally to reduce COVID-19 transmission and CFR C_LI
ABSTRACT
The presence of SARS-CoV-2 genetic materials in wastewater has become a matter of grave for many countries of the world. Wastewater based epidemiology, in this context, emerged as an important tool in developed countries where proper sewage system is available. Due to the recent shift in the spread of the infection from urban to rural areas, it is now equally important to develop a similar mechanism for rural areas as well. Considering the urgency of the issue a study was conducted in 14 districts of Bangladesh and a total of 238 sewage samples were collected in two different periods from December 2020 to January 2021. We are the first to propose a surveillance system for both urban and rural areas where a proper sewage system is absent. Based on RT-PCR analysis of the water samples, in more than 92% of cases, we found the presence of the SARS-COV-2 gene (ORF1ab, N, and Internal Control-IC). The trend of Ct value varies for different study locations. The spread of genetic material for on-site ({Delta}m = 0.0749) sanitation system was found more prominent than that of off-site sewage system ({Delta}m = 0.0219); which indicated the shift of genetic material from urban to rural areas. Wastewater samples were also measured for physicochemical parameters, including pH (6.30 - 12.50) and temperature (22.10 - 32.60) {o}C. The highest viral titer of 1975 copy/mL in sewage sample was observed in a sample collected from the isolation ward of the SARS-COV-2 hospital. Additionally, a correlation was found between bacterial load and SARS-CoV-2 genetic materials. The results indicated the association of increased Ct values with decreasing number of patients and vice versa. The findings reported in this paper contributed to the field of wastewater-based epidemiology dealing with SARS-COV-2 surveillance for developing countries where proper sewage system is absent and highlighting some of the challenges associated with this approach in such settings. HighlightsO_LIDevelopment of wastewater-based surveillance system based on on-site sanitation system for developing countries. C_LIO_LIAssociation of different environmental parameters with the presence of SARS CoV-2 genetic material in wastewater. C_LIO_LIPrediction of the viral concentration of sewage system using viral load and copy number parameter. C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=122 SRC="FIGDIR/small/21261347v2_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@1f7847dorg.highwire.dtl.DTLVardef@11b2c93org.highwire.dtl.DTLVardef@10b9fe1org.highwire.dtl.DTLVardef@2d9e8d_HPS_FORMAT_FIGEXP M_FIG C_FIG
