Plasma is a pale yellow liquid component of blood composed primarily of water, proteins, salts, antibodies, and clotting factors. This fluid is separated from red blood cells and platelets through a process called plasmapheresis. Collected plasma is not used directly for transfusion but is fractionated to create specialized, life-saving therapies for immune deficiencies, hemophilia, and various neurological disorders. Because these products are administered to patients, the donation process is highly regulated and must meet stringent safety standards. The requirement for a second donation is a fundamental step in ensuring the safety and integrity of the source material.
The Infectious Disease Window Period
The primary reason a second donation is required is to manage the risk associated with the infectious disease “window period.” This period is the time gap between a person becoming infected with a pathogen, such as HIV or Hepatitis, and when that infection is detectable by standard screening tests. During this initial stage, a donor could be newly infected but test negative on the day of their first donation. This creates a theoretical risk that the plasma collected could contain a virus despite the negative test result.
Current testing methods, including Nucleic Amplified Testing (NAT), are highly sensitive but still require a small viral load to be present before they register a positive result. To close this safety gap, the industry requires a subsequent donation and retesting. The first donation is considered potentially unsafe until a follow-up test, conducted after the typical window period has elapsed, confirms the donor remains non-reactive. This two-step process provides an extra layer of assurance for patient safety.
Quarantine and Release Protocols
The regulatory framework that governs plasma collection mandates a strict quarantine protocol for the initial donation, which cannot be released until the donor successfully completes a second safety screening. The plasma from the first donation is collected, tested, and immediately placed on hold. This material is kept in a frozen state, sometimes for up to six months, awaiting the donor’s return.
For the initial plasma to be used, the donor must return and provide a second sample, generally within two to six months, which is then tested again for infectious disease markers. If the second test is also negative, it confirms that the donor was not in the infectious disease window period at the time of the first donation. Only then is the initial unit of plasma released from quarantine and deemed acceptable for further manufacturing into therapies.
If the donor does not return for the second donation, or if the second test yields a reactive result, the first unit of plasma must be destroyed, ensuring that no potentially unsafe material enters the supply chain. These protocols are supported by regulatory requirements, such as the U.S. Food and Drug Administration’s (FDA) regulations found in 21 CFR 610.46, which includes “lookback” procedures for prior collections. This rule requires the quarantine and management of previous donations if a donor later tests positive for a transmissible disease. The two-donation rule essentially preempts the need for a lookback by establishing a baseline of safety through repeated testing before the plasma is utilized.
Maintaining Donor Eligibility and Safety Standards
Beyond the initial two-donation requirement, consistent, repeated testing is necessary for a donor to maintain eligibility and for the plasma center to ensure the ongoing integrity of the supply. Every donation session requires a comprehensive health screening to monitor the donor’s well-being and identify any new risk factors that may have emerged since the last visit. This recurrent screening process involves checking vital signs, including blood pressure, pulse, temperature, and weight, before the donor is permitted to proceed with the donation.
A small blood sample is collected at every appointment and tested for markers of transmissible diseases like HIV, Hepatitis B, and Hepatitis C. The continuous monitoring of a donor’s health status and test results ensures that any change in infectious status is identified immediately, preventing potentially unsafe plasma from entering the manufacturing process. This cyclical system of screening and testing reinforces the high safety standards required by regulatory bodies, confirming that the donor is consistently monitored.