November 29, 2021

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SARS-CoV-2 variants similar to Delta can exacerbate the COVID-19 pandemic

SARS-CoV-2 variants similar to Delta can exacerbate the COVID-19 pandemic



 

Cell: SARS-CoV-2 variants similar to Delta variants can exacerbate the COVID-19 pandemic. 

In a new study, researchers from the Harvard TH Chan School of Public Health in the United States constructed a mathematical model and found:

A SARS-CoV-2 variant with similar characteristics to the Delta variant—enhanced transmission and The ability to infect people who have previously been infected/vaccinated — will cause a more serious pandemic, resulting in more infections and breakthroughs than the SARS-CoV-2 variant that has one of these two characteristics alone Sexual infection/reinfection.

 

These findings may help scientists and public health officials explain the importance of new and existing variants, and design targeted public health responses for various situations based on the characteristics of the variants.

The relevant research results were published online in the Cell Journal on November 18, 2021. The title of the paper is “Population impact of SARS-CoV-2 variants with enhanced transmissibility and/or partial immune escape”.

 

SARS-CoV-2 variants similar to Delta can exacerbate the COVID-19 pandemic

 

The first author of the paper and the corresponding author of the paper, and a postdoctoral researcher in the Department of Epidemiology at Harvard TH Chan School of Public Health, said Mary Bushman, “So far, immune escape—a variant that evades the immune system and leads to reinfection or The ability to break through infection — the evidence is like a red flag (dangerous signal). Our research results suggest that this may be more like a yellow flag — this is not a big problem in itself. But When it is combined with enhanced communicability, then it can be a real big problem.”

 

As the COVID-19 pandemic progresses, variants of the original wild-type SARS-CoV-2 virus have emerged. Some variants quickly became dominant strains and increased the number of infections, such as Alpha variants and Delta variants, while other variants, such as Beta variants, failed to dominate or contributed significantly to the development trajectory of the COVID-19 pandemic.

In order to understand the impact of certain factors on the COVID-19 pandemic, Bushman constructed a mathematical model that simulates how the pandemic driven by hypothetical variants will affect various combinations of wearing a mask and physical distance and vaccination. 

 

The analysis simulates several different hypothetical variants of the COVID-19 pandemic. These variants include multiple combinations of two characteristics: enhanced transmission, similar to Alpha variants; partial immune escape, similar to Beta variants ; Enhanced transmission and partial immune escape, similar to Delta variants; and variants that do not have either of these two characteristics.

The analysis also considers how certain variables, such as wearing a mask/physical distance or vaccination, will affect the trajectory of the COVID-19 pandemic. For each case, the authors analyzed the total number of infections and the percentage of infections that were avoided through vaccination.

 

SARS-CoV-2 variants similar to Delta can exacerbate the COVID-19 pandemic

Picture from Cell, 2021, doi:10.1016/j.cell.2021.11.026.

 

Bushman and his team determined that variants with only enhanced transmission may be more dangerous than variants that partially evade the immune system. However, variants with these two characteristics may cause more infections, re-infections, and breakthrough infections than variants with either of these characteristics alone.

 

According to this mathematical model, it is also very useful to predict vaccination in the case of a SARS-CoV-2 variant similar to the Delta variant, because vaccination will prevent a more transmissible virus from potentially causing more infections. , And the mild nature of breakthrough infections should greatly reduce overall mortality.

 

William P. Hanage, co-author of the paper and associate professor of the Department of Epidemiology at Harvard TH Chan School of Public Health, said, “It is true that people recognize that the emergence of variants like Delta variants makes high-level vaccination even more critical. Very important.

Even if we can’t eliminate this virus, we can ensure that people are best prepared to face it, and a more transmissible virus means that there will be more without vaccinations. Infection, so more people can benefit from vaccination.”

 

 

 

Reference:

Mary Bushman et al. Population impact of SARS-CoV-2 variants with enhanced transmissibility and/or partial immune escape. Cell, 2021, doi:10.1016/j.cell.2021.11.026.

SARS-CoV-2 variants similar to Delta can exacerbate the COVID-19 pandemic

(source:internet, reference only)


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