Even with the latest increase, cases in the US are nowhere near their peak of 250,000 per day in January [File: Julia Rendleman/Reuters]

New York, July 14 (RHC)-- The coronavirus infections curve in the United States is rising again after months of decline, with the number of new cases per day doubling over the past three weeks, driven by the fast-spreading Delta variant, lagging vaccination rates and Fourth of July gatherings.

Despite having one of the highest vaccination rates in the world, new daily infections in the US have doubled over the past two weeks to an average of about 24,000, according to the Centers for Disease Control and Prevention (CDC).  Deaths linked to the coronavirus are still on a downward trajectory at around 260 a day.

“It is certainly no coincidence that we are looking at exactly the time that we would expect cases to be occurring after the July Fourth weekend,” said Dr Bill Powderly, co-director of the infectious-disease division at Washington University’s School of Medicine in St Louis.

At the same time, parts of the country are running up against widespread vaccine resistance, while the highly contagious version of the coronavirus that was first detected in India is accounting for an ever-larger share of infections.

Nationally, 67.7 percent of American adults have received at least one COVID-19 jab, according to data from the CDC. The five states with the largest, two-week jump in cases per capita all had lower vaccination rates.

But even with the latest surge, cases in the U.S. are nowhere near their peak of 250,000 per day that was recorded in January – a testament to how effectively vaccines can prevent serious illness and death in those who become infected.

Still, the rise has prompted health authorities in places such as Los Angeles County and St Louis to urge residents, including those who have been vaccinated, to resume wearing masks in public.

Officials in the city of Chicago announced on Tuesday that unvaccinated travellers from Missouri and Arkansas must either quarantine for 10 days or have a negative COVID-19 test, while the health department in Mississippi, which ranks last for vaccinations, began blocking COVID-19 posts on its Facebook page amid a “rise of misinformation” about the virus and the vaccine.