About 83 percent of new COVID-19 cases in the U.S. have been fueled by the delta variant, and as the surge continues, the number of associated cases is expected to rise even higher in the coming weeks, according to health officials.
Approximately one month ago, on June 19, the delta variant accounted for just over 30 percent of new cases. On July 3, it crossed the 50 percent threshold to become the dominant variant in the U.S. Public health experts nationwide have focused their efforts on encouraging vaccinations as most of those who've contracted the variant haven't been vaccinated.
Studies have shown that the COVID-19 vaccines are effective against multiple variants, including the delta variant. However, when it comes to symptoms, there appear to be key differences.
"“It seems like cough and loss of smell are less common," Dr. Inci Yildirim, a Yale Medicine pediatric infectious diseases specialist, said in a news release. "And headache, sore throat, runny nose, and fever are present based on the most recent surveys in the U.K., where more than 90% of the cases are due to the delta strain."
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It’s not yet clear why cold-like symptoms are increasingly being reported, or if there is a link to the delta variant. The implications of such a change — if it exists — are also not yet known. A wide range of symptoms have been associated with the coronavirus, and the U.S. Centers for Disease Control and Prevention includes congestion and runny nose on its list of potential COVID-19 symptoms.
Compared to other strains, the delta variant is significantly more contagious.
According to scientists at Yale Medicine, the delta variant is 50% more contagious than the alpha variant, which originated in the United Kingdom and is the most common strain of the virus seen in Illinois.
The alpha variant was 50% more contagious than the original strain of COVID-19, meaning that the number of people that could potentially be infected by each COVID-positive individual is significantly higher.
A study published June 14 in the journal The Lancet examined the impact of the delta variant in Scotland, where it had become the dominant strain. The researchers found that the risk of hospitalization from COVID-19 was roughly doubled for patients infected with delta, compared with people infected with the alpha variant.
“If for comparison we look at the original strain, the U.K. [alpha] variant and now the delta one, we are noticing that there is a difference in transmissibility, as well as the potential for more dangerous outcomes,” Dr. Alejandro Perez-Trepichio, an internal medicine physician based in Florida told NBC News.