And for my money, the best show in TV's greatest decade was Lost in Space. It's impossible to describe what watching this show was like in the 1960s. It's an experience that simply can't be re-produced today.
The reaction reaches its peak about 48 to 72 hours after the PPD is injected. Waiting too long or not long enough may cause an underestimation of the reaction and, therefore, affect how the test is read.A positive test will cause redness, itching and a raised, hardened area of skin called an induration.
The PPD test also take 48-72 hours and requires at least two visits to complete. This may delay a candidateâs employment start date and cause travel inconveniences. A QuantiFERON instead is performed in one visit and analyzed by a laboratory to rule out false positives.