A blood collection device comprising: a housing; a plunger slideably mounted within the housing, sidewalls of the plunger defining a retraction lumen within the plunger; a needle seal (246, 246A) frictionally engaged within the retraction lumen at a distal end of the plunger, the needle seal (246, 246A) having a sealing engagement structure (264, 274) on a distal side thereof; a needle initially secured at a distal portion of the housing; a needle support structure (218, 218A) frictionally engaged in the distal portion of the housing for initially securing the needle in place, a first portion of the needle support structure (218, 218A) being moveable in a distal direction in response to application of an activation force against the plunger by a user, a second portion (270, 276) of the needle support structure (218, 218A) being shaped and configured to engage with the sealing engagement structure (264, 274) of the needle seal (246, 246A) upon the application of the activation force against the plunger by the user to provide a needle retraction assembly including the needle; a propellant chamber positioned in the housing distally of the needle support structure (218, 218A); rupturing spikes provided proximally of the propellant chamber and distally of the needle support structure (218, 218A), the rupturing spikes being moveable to rupture the propellant chamber upon the application of the activation force against the plunger by the user; and a blood collection outlet for passing blood flowing through the needle to a blood collection reservoir; a blood flow path being provided through the needle and past the plunger to the blood collection outlet when the blood collection device is in its initial configuration, whereby the application of the activation force against the plunger by the user moves the plunger distally within the housing to engage the needle seal (246, 246A) with the second portion (270, 276) of the needle support structure (218, 218A) to form the needle retraction assembly and causes the first portion of the needle support structure (218, 218A) to move distally within the housing to cause the rupturing spikes to release propellant from the propellant chamber, so that the released propellant retracts the needle retraction assembly and the needle within the retraction lumen. a housing; a plunger slideably mounted within the housing, sidewalls of the plunger defining a retraction lumen within the plunger; a needle seal (246, 246A) frictionally engaged within the retraction lumen at a distal end of the plunger, the needle seal (246, 246A) having a sealing engagement structure (264, 274) on a distal side thereof; a needle initially secured at a distal portion of the housing; a needle support structure (218, 218A) frictionally engaged in the distal portion of the housing for initially securing the needle in place, a first portion of the needle support structure (218, 218A) being moveable in a distal direction in response to application of an activation force against the plunger by a user, a second portion (270, 276) of the needle support structure (218, 218A) being shaped and configured to engage with the sealing engagement structure (264, 274) of the needle seal (246, 246A) upon the application of the activation force against the plunger by the user to provide a needle retraction assembly including the needle; a propellant chamber positioned in the housing distally of the needle support structure (218, 218A); rupturing spikes provided proximally of the propellant chamber and distally of the needle support structure (218, 218A), the rupturing spikes being moveable to rupture the propellant chamber upon the application of the activation force against the plunger by the user; and a blood collection outlet for passing blood flowing through the needle to a blood collection reservoir; a blood flow path being provided through the needle and past the plunger to the blood collection outlet when the blood collection device is in its initial configuration, whereby the application of the activation force against the plunger by the user moves the plunger distally within the housing to engage the needle seal (246, 246A) with the second portion (270, 276) of the needle support structure (218, 218A) to form the needle retraction assembly and causes the first portion of the needle support structure (218, 218A) to move distally within the housing to cause the rupturing spikes to release propellant from the propellant chamber, so that the released propellant retracts the needle retraction assembly and the needle within the retraction lumen.