In a recent research paper published on medRxiv* Preprint server Scientists from the Yale School of Public Health have analyzed deaths associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the United States (US).
Study: Million and Count: Estimates of mortality in the United States from ancestral SARS-CoV-2 and variants. Image Credit: Gargantiopa / Shutterstock
New variants of SARS-CoV-2 with high virulence, transmissibility and immune evasion due to the worldwide transmission of the sustained worldwide coronavirus disease 2019 (COVID-19) have emerged since its emergence in Wuhan, China, at the end of 2019. In the United States, more One million deaths associated with SARS-CoV-2 have been reported to date. In addition, the SARS-CoV-2 mutations identified worldwide have altered the course of the COVID-19 epidemic in the United States several times.
As of May 12, 2022, the World Health Organization (WHO) has described five different types of SARS-CoV-2 of concern (VOCs), first found on four distinct continents. All five VOCs were more infectious than the original SARS-CoV-2 strain and spread to the United States. COVID-19 vaccines based on unmutated SARS-CoV-2 (ie non-VOC SARS-CoV-2) are poorly effective against Omicron infections and Delta VOCs but highly effective against severe diseases. Notably, over the course of the SARS-CoV-2 epidemic in the United States, the specific death burden of each viral variant remains unknown.
The aim of this study was to calculate the number of deaths from all SARS-CoV-2 mutations in the United States. Scientists built an epidemiological model to determine the number of documented COVID-19 deaths in the United States attributable to each SARS-CoV-2 mutation. They used information obtained from the Centers for Disease Control and Prevention (CDC) on SARS-CoV-2-related deaths by jurisdiction and proportions of circulating viral variants. Furthermore, to address the uncertainty in the parameters, the team performed a sensitivity assessment.
The current analysis was based on provisional figures for SARS-CoV-2 deaths from the National Center for Health Statistics (NCHS) of the Centers for Disease Control. This data was accessed as of May 12, 2022.
To get the number of documented COVID-19 deaths caused by each SARS-CoV-2 variant, the team again distributed deaths to determine the proportion of fatal COVID-19 cases tested daily in each jurisdiction and then compared these statistics with percentages of the variables between cases. Serialized at the exact site and time point, controlling for differences in disease severity between variables.
Given the time interval between onset of symptoms, testing, and deaths, the team used lag periods to estimate the timing of sample procurement for new deaths. They predicted that sampling for testing occurred one, one, two or three days after the onset of symptoms, with a probability associated with 25% for all of these four possible periods of delay in initial assessment. The researchers also hypothesized that there was a gap between the onset of symptoms and death.
The authors explained that 46% (460,124) of the 1,003,419 SARS-CoV-2 deaths documented as of May 12, 2022 were attributable to SARS-CoV-2 variants identified by the World Health Organization in the United States at the national level. On the other hand, 54% of all COVID-19 deaths have been attributed to unchanged SARS-CoV-2.
The researchers demonstrated the effect of SARS-CoV-2 variants across the United States. Variants caused a large number of deaths in all regions. The South had the highest per capita mortality, with a median estimate of 158 per 100,000, while the Northeast had the lowest, with a median estimate of 111 per 100,000, by US census district. Some regions were disproportionately affected, due to disparities in vaccination coverage, demographics, pre-existing immunity, community vulnerabilities, and use of a non-pharmaceutical intervention.
SARS-CoV-2 Alpha, with an average estimate of 39,548 deaths, Omicron (117,560) and Delta (273801) were expected to be responsible for approximately 40% of national COVID-19 deaths. In fact, the 3,628 deaths from COVID-19 documented by the NCHS cannot be assigned to the SARS-CoV-2 variant because the week of deaths is not specified statewide in the data.
Study results show that SARS-CoV-2 mutations that have been detected worldwide have claimed a large number of lives in the United States. Variants of SARS-CoV-2 that were initially found outside the United States were responsible for more than 40% of COVID-19 deaths in the country.
The current study supports the claim that “no one is safe until everyone is safe” by demonstrating the observed effect of SARS-CoV-2 mutations on mortality in the United States, which appeared near uncontrolled circulation both locally and globally. This analysis suggests that rapid implementation of mitigation methods for emerging variants of SARS-CoV-2 after the onset of a viral epidemic may be beneficial. The authors note that more efforts are needed to reduce the potential for novel variants of SARS-CoV-2 to emerge, including global COVID-19 vaccination and treatment and outbreak management, regardless of national public health policies.
To summarize, the current work underscores the risk to Americans posed by novel SARS-CoV-2 variants, a risk that is exacerbated by poor global vaccination rates for COVID-19 and the paucity of treatments, diagnoses, and preventive methods for SARS-CoV-2 infection.
medRxiv It publishes preliminary scientific reports that have not been peer-reviewed and therefore should not be considered conclusive, guide clinical practice/health-related behaviour, or be treated as established information.