The immediate action after a needlestick injury with HIV-positive blood is to wash the area thoroughly with soap and water. This helps to reduce the viral load at the site of injury and lowers the risk of HIV transmission. Using soap and water ensures effective mechanical removal of blood and potential virus particles. Alcohol-based sanitizers do not replace washing and may be insufficient. Prompt cleansing is critical before any further post-exposure prophylaxis measures. Delaying or ignoring this step increases the risk of infection.

Reference: Harrison's Principles of Internal Medicine, Fauci et al., 20th Edition.