What makes the Delta variant more contagious?

The Delta variant is getting plenty of attention in Australia, and is currently the cause of concern in Sydney. Let’s take a look at what makes this variant different and concerning.  

Quickly, what is the Delta variant? 

Originally identified in India in October 2020, the Delta variant is considered a highly contagious strain and is classified as a “variant of concern” by the WHO. Its other names include B.1.617.2 and the Indian variant.

What makes this variant so different from the others? 

The main point of concern about the Delta variant is that it is highly contagious. So contagious in fact, that scientists believe it has the ability to spread in just 5-10 seconds of contact – this is where we’ve seen the rise in “fleeting transmission” like in Sydney’s Westfield. Not all cases spread that quickly, but it has the ability to do so. For context, one study showed the strain spreads about 225% faster than the original version of the virus. On average, it takes around four days for the Delta variant to reach detectable levels, compared to six days for the original COVID-19 variant. Overall, it is understood the Delta variant is about 60% more transmissible than the Alpha variant. 

The Delta variant has over 20 mutations compared to the original strain of COVID-19, with some of these mutations containing alarming characteristics. The Delta variant has mutations in the spike protein of the virus that attaches to human cells to infect them. The virus can reproduce more effectively because of these mutations in the spike protein. Scientists have also found that Delta mutates into regions that antibodies (the stuff that fights COVID) are less effective in.

Severe outcomes 
Further evidence shows the Delta variant can cause more severe outcomes for those who contract the virus. One study looking at 5.4 million people in Scotland found that infections with Delta were more than twice as likely to lead to hospitalisations compared to the Alpha variant.

Best prevention? 
Vaccines still remain the best possible way of preventing severe illness and death from these mutant forms of the virus — including the Delta variant. Additionally, the usual COVID-19 hygiene practices of social distancing, mask-wearing and hand washing are still very effective and reduce the risk of becoming infected.

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