New COVID-19 diagnoses have risen sharply in New Jersey ever since the Independence Day holiday, the lowest point in the state’s daily case count. Experts attribute that spike to the growing presence of the highly transmissible delta variant of the virus. Hospitalizations — a key metric in determining public health requirements — are also rising, but at a far slower pace.

While the reported number of new cases see-saws significantly based on the day of the week, with fewer people likely to be tested on Sundays and Mondays, a NJ Spotlight News analysis of state data paints a clear picture overall. The viral spread has driven daily case counts from 86 new diagnoses on July 5 to a peak of 1,313 on Aug. 3.

At the start of July, New Jersey was testing about one in 10 diagnoses to identify which strain caused the infection. Delta accounted for just 16% of the variants found in those tests, NJ Spotlight News found in a review of state data. By Aug. 4 delta accounted for 84% of the tests sequenced, while more than a dozen other strains accounted for the remaining 16%.

On the up side, New Jerseyans continue to get vaccinated against the virus. The number of doses administered daily has dropped from early July — when nearly 80,000 individuals got a shot over two days — to between 2,000 and 24,500 inoculations every day since. More than 5.3 million residents are now fully immunized.

While the delta variant can spread via immunized hosts and the number of breakthrough cases, or infections among vaccinated people, is growing, studies show the vaccines are extremely effective in protecting against severe illness and death.