The delta variant of the coronavirus was detected in India in February of 2021, causing a huge rise in infections. By June, it was the dominant variant of the virus in the United Kingdom, and by July, it had infiltrated all 50 states.
Though the resurgence was frightening and continues to affect global efforts to eradicate COVID-19, viral variants are normal. Some pop up and quickly fade away, while others, like the delta variant, become more of a concern for public health.
The delta variant arose from errors in viral replication. The coronavirus uses a layer of protein spikes called a corona to enter our cells. The spikes act as keys, engaging with receptors on the surface of our cells to get inside.
Once the virus enters the cell, it replicates, making copies of its genes. Most of the time, it creates a carbon copy of itself, but not always.
When the coronavirus replicates, it makes random errors. Sometimes, these errors do not change anything, or they may even make the virus less potent. Other times, like in the delta variant, these errors benefit the virus. Over time, more errors appear. Eventually, the mutations are enough to significantly change the behavior of the virus.
The symptoms of the delta variant are the same as the original coronavirus, predominantly fever, cough, difficulty breathing, sore throat, headache, and diarrhea. Other symptoms include loss of taste and smell, fatigue, and a runny nose.
Typically, vaccinated people with breakthrough delta variant infections have very mild symptoms that mimic the common cold or no symptoms at all.
While the symptoms of the delta variant are the same as the original coronavirus, there are some significant differences between them. Delta symptoms seem to make people sicker more quickly, and they affect younger people more than other variants, which may be because delta replicates faster and to much higher levels, according to new studies.
Another significant difference is that delta is more than twice as contagious as previous variants.
Some studies from Scotland and Canada show that people with delta may be more likely to be hospitalized than those with the original virus. But because delta is more contagious, it is difficult to determine if it is making people sicker or if it is circulating faster among at-risk individuals where vaccination rates are low and hospital systems cannot handle the patient load. Mortality varies across countries and death rates are not broken down by viral variants.
Vaccines are highly effective against the delta variant, and experts believe they play an important role in controlling the spread. Vaccines are not 100 percent effective, however, and some vaccinated people will still become infected, though their symptoms are much less severe. Low vaccination rates in some areas are driving the spread of the delta variant and increasing the chance that more concerning variants could emerge.
There are many other variants of the coronavirus, including Alpha, Beta, Gamma, Epsilon, Ets, Iota, Kappa, Mu, and Zeta, though, so far, none have been as contageous as Delta. Mutations and new variants can make a virus more deadly, but being more deadly it is not advantageous to the virus. If a virus kills its host, it has less of a chance to spread.
Variants of interest have markers indicating that they may not bind to cell receptors in the same way, which can lead to less effective treatments, reduced effectiveness of antibodies from either a vaccine or previous infection, or an increase in severity or contagiousness.
When health officials identify a variant of interest, they may respond by watching the variant more closely, performing enhanced lab studies, or monitoring how well vaccines and existing treatments are working.
The Delta variant is classified as a variant of concern; it has shown evidence that it is more transmissible, more severe, or does not respond the same way to treatments or vaccines. Because of this classification, officials may take increased steps to control the spread or ramp up testing. If necessary, they may start to explore new treatments or modifications to those currently in use.
The more infections there are, the more likely it is that the virus will mutate again, and for every mutation, there is a chance that the virus will improve itself to be more deadly.
The delta variant fueled the latest coronavirus surge, but if the virus continues to spread, more dangerous and transmissible variants may follow. The best way to control the development of new variants is to stop the spread of the virus through methods such as vaccination and more careful interactions.
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