The spread of the highly transmissible delta variant is accelerating amid the still-raging fourth wave of the COVID-19 pandemic.

Health authorities said Tuesday that three-thousand-62 cases of four major variant strains were reported from August 15 to the 21. About 99 percent of those cases, or three-thousand-33, were the delta strain.

The other 29 cases were the alpha variant.

The majority of both local and overseas transmissions in the past week were also the delta variant, as it has clearly become the dominant strain worldwide. The delta detection rate has reached nearly 90 percent.

The total caseload of alpha, beta, delta and gamma variants combined since last December stands at 16-thousand-842. Delta takes up close to 13-thousand-500, followed by alpha at over 32-hundred cases.