Allergies are the result of a hypersensitive immune system. The allergic immune system misidentifies an otherwise innocuous substance as harmful, and then attacks the substance with a ferocity far greater than required.
Laying off an employee is different from firing an employee. Firing means letting a worker go for any reason, whereas a layoff refers to an employment termination based on economics, usually involving more than one worker.
Dismissal or firing is generally thought to be the fault of the employee, whereas a layoff is generally done for business reasons (for instance a business slowdown or an economic downturn) outside the employee's performance.