August 23, 2016
By Toby Simon, MD
Zika virus has been widely reported in the news during the past year, so much so that a number of athletes chose to stay home rather than compete in the Olympics in Rio de Janeiro and risk infection. We therefore understand that patients treated with our plasma derived products want to be certain they are not at risk for infection with Zika virus through their treatment with our products.
Infection with the Zika virus generally results in no symptoms, but 20% or more of individuals infected will have a mild illness of 5 to 7 days with fever, rash, headache, and discomfort in their hands, wrists, and ankles. This virus has also been associated with Guillain-Barre syndrome, a self-limited disease of the nervous system that can be serious.
Most of the public health concern relates to infection in pregnant women, because microcephaly (incomplete brain development) and other fetal defects have resulted from infection with this virus. The virus is spread by mosquito bites, but there is evidence of transmission through sexual contact and blood transfusion. The virus has been most common in tropical areas. The epidemic is severe in Puerto Rico and has emerged in the United States through both travel and in the last month from local mosquito transmissions in south Florida.
Zika virus is not a significant concern for CSL Behring’s plasma-derived products, which are used to treat chronic, life-threatening diseases. These include bleeding disorders, Alpha-1-Antitrypsin deficiency, primary immune deficiencies, hereditary angioedema, and certain rare disorders of the nervous system. Our therapies are also used in emergency and surgical medicine.
Patient safety is of paramount importance to everything we do at CSL Behring, and our integrated processes incorporate dedicated pathogen safety measures that help assure the safety and quality of our products. The plasma (the clear liquid portion of blood that remains after blood cells are returned to the donor) used as the starting material for our products comes from carefully screened plasma donors without known risk factors.
Donors who show any signs of infection such as fever are deferred from donating. All the plasma we collect is tested for some infectious diseases using state of the art technologies. All our manufacturing (fractionation) processes contain dedicated virus inactivation and/or removal steps that are designed to maintain a high margin of safety against a broad spectrum of viruses, both known pathogens, e.g. HIV, and potential emerging viruses such as Zika.
Zika is a flavivirus, a family of viruses that share similar chemical and physical features. We have considerable experience with other flaviviruses, and published studies show that our processes have the capability to inactivate or remove this type of virus. This family of viruses includes West Nile virus, which is a flavivirus similar to Zika virus. To date, no confirmed reports of West Nile virus transmission by any of CSL Behring’s products have been reported, providing additional data indicating that our existing virus safety measures are also effective against Zika virus.
We have data showing that West Nile virus and other model viruses with similar physical and chemical properties to Zika virus are rapidly inactivated by process steps such as pasteurization, dry heat treatment, solvent detergent treatment, and low pH incubation and would be removed by virus filtration and/or other purification steps.
Our scientists continue to vigilantly monitor and evaluate emerging viruses, such as Zika, to confirm that our donor screening and manufacturing procedures provide a high degree of protection from virus transmission to patients receiving our products. As a part of these efforts, we have conducted laboratory studies with the actual Zika virus that confirm the effectiveness of our current virus inactivation and removal steps. Taken together, these data continue to show that our products enjoy a significant safety margin relative to the Zika virus.
We are driven by our promise to deliver safe, high quality products for patients with rare and serious medical disorders.
Note: CSL Behring makes many products that are derived from components of human blood. The risk of transmission of infectious agents, including viruses and, theoretically, the Creutzfeldt-Jakob disease (CJD) agent, cannot be completely eliminated.
Dr. Simon is Senior Medical Director, Plasma and Plasma Safety, CSL Behring