Plasma donation involves collecting blood, separating the liquid component (plasma), and returning the remaining blood components to the donor. This plasma is used to manufacture life-saving therapies, such as immunoglobulins and clotting factors. Herpes Simplex Virus (HSV), including HSV-1 (oral cold sores) and HSV-2 (genital herpes), is a highly prevalent viral infection. The history of this infection often raises questions about donation eligibility.
Herpes Simplex Virus and Donation Eligibility
The general regulatory stance is that a history of Herpes Simplex Virus (HSV) infection does not automatically disqualify an individual from donating plasma. The virus establishes a latent, lifelong infection in nerve cells. When asymptomatic, HSV is not considered a high-risk transfusion-transmissible agent. Therefore, having experienced an HSV outbreak does not result in a permanent deferral.
Regulatory bodies do not categorize HSV in the same high-risk group as chronic bloodborne pathogens like HIV or Hepatitis B and C, which require permanent deferral. HSV is primarily a localized infection, and during periods of latency, the virus is not actively circulating in the bloodstream at levels that pose a significant risk. Most individuals with HSV are eligible to donate plasma, provided they meet all other standard health and screening requirements.
Research indicates that viremia, the presence of the virus in the blood, is rare and tends to be limited to the initial, or primary, infection, especially in cases of severe illness. For the vast majority of people who experience recurrent, localized outbreaks, the virus does not typically circulate in the blood in a way that would pose a known threat to recipients. This understanding allows for the acceptance of donors with a history of recurrent HSV infections.
Deferral Criteria Based on Active Symptoms
While a history of HSV does not prevent donation, the donor’s immediate physical state at the time of the appointment is paramount in determining eligibility. Any active manifestation of the Herpes Simplex Virus, such as fresh lesions, blisters, or cold sores, is a cause for a temporary deferral. This restriction is put in place because an active outbreak indicates the virus is replicating, potentially increasing the chance of viral particles being present in the bloodstream.
The temporary deferral remains in effect until the active symptoms have completely resolved. Donation centers typically require that the lesions are fully healed, scabbed over, or otherwise symptom-free. This ensures that the donor is past the peak period of viral activity before proceeding with the plasma collection. In some cases, a deferral period may also apply for a short time, such as 48 hours, following the completion of any antiviral medication taken to treat the outbreak.
Plasma donation requires the donor to be in good general health. Any systemic symptoms associated with a primary or severe recurrent outbreak will also lead to a deferral. Symptoms like fever, general malaise, or feeling unwell are reasons to postpone the donation, regardless of the localized lesion status.
Safety Measures in Plasma Screening and Processing
The safety of plasma-derived medicinal products relies on a multi-layered approach often referred to as the “Safety Tripod,” which includes donor selection, donation testing, and robust manufacturing processes. Even after careful donor screening, the plasma collected is subjected to intensive purification steps designed to eliminate or inactivate potential pathogens, including enveloped viruses like HSV. This processing provides a substantial margin of safety for the final therapeutic products.
The manufacturing process for fractionated plasma products incorporates dedicated virus inactivation and removal steps. One highly effective method is the solvent/detergent (S/D) treatment, which is specifically designed to disrupt the lipid envelope surrounding viruses such as HSV. Since the implementation of S/D treatment in the 1980s, there have been no reported transmissions of enveloped viruses through human plasma-derived products.
Other methods, such as pasteurization (heat treatment) or nanofiltration, also contribute to viral safety. Nanofiltration uses specialized filters with extremely small pore sizes to physically remove viral particles based on their size. This combination of multiple, complementary steps ensures that even if trace amounts of a lipid-enveloped virus like HSV were present in the initial donation, the manufacturing process significantly reduces the risk of transmission to the final product.