The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is responsible for coronavirus disease 2019 (COVID-19), has disrupted all of our lives. While the mortality rate is significantly less than its predecessors (i.e. SARS-CoV, Middle East respiratory syndrome or MERS), its global transmission is unprecedented. This can be partially attributed to the high rate of asymptomatic and mildly symptomatic individuals; the virus is easily spread by those who don’t even realize they have it. So while the mortality rate and prevalence of severe disease among those infected may pale in comparison to previous outbreaks, the total number of patients infected brings the number of life threatening cases to potentially overwhelming levels.
As this is a novel virus, no specific therapeutic agents or vaccines are available. The FDA recently issued an emergency investigational new drug protocol (eIND) for the use of COVID-19 convalescent plasma as treatment in patients with severe or life-threatening disease. COVID-19 convalescent plasma is plasma from individuals who have recovered from COVID-19 and have antibodies to the virus in their blood. Infusing the plasma from recovered individuals to treat those with the disease is not a new concept, it was used in the 1918 Spanish flu epidemic. The idea is to transfer passive immunity to the patient. It has also been used with other recent viral outbreaks such as SARS-CoV and H1N1 influenza, and was recommended as empirical treatment for Ebola virus in 2014 and MERS in 2015. Studies in these settings, as well as limited data treating COVID-19 patients, has shown promise.
The FDA has set criteria for donor eligibility to donate convalescent plasma. First, these potential donors must meet all regular FDA donor eligibility requirements for blood donation and/or plasma donation by apheresis. Second, the donors must have laboratory proof of previous infection, either through a positive diagnostic test (i.e. NP swab) at the time of illness or a positive serologic test for antibodies after recovery. Third, the donor must be recovered, defined as 14 days after complete resolution of symptoms with a negative COVID-19 test result, or 28 days after complete resolution of symptoms and no COVID-19 testing required. Fourth, the donor should have no risk for HLA antibodies in order to decrease the risk of transfusion related acute lung injury. For this reason, male donors and female donors without a history of pregnancy are preferred; female donors with a history of pregnancy require HLA antibody testing. Last, titers of neutralizing antibodies should be tested for if available, and samples stored for future testing if not available.
Kentucky Blood Center was one of the first in the country to begin collecting convalescent plasma from recovered COVID-19 patients just three days after the eIND was issued by the FDA. Since that time, plasma has been collected from more than 15 recovered COVID-19 patients. The first local donation transfusion recipient was recently released from the hospital after a lengthy stay and an extended period of critical care.
Hospitals have been critical in helping find recovered COVID-19 patients to make the plasma donations and Kentucky Blood Center fully vetted the potential donors and completed the pre-donation screening and the collection of the plasma. Most donors are able to donate enough plasma to help two patients. Kentucky Blood Center has developed a registry for recovered COVID-19 patients wishing to donate plasma and also urges anyone who believes they may have been infected to register. When reliable FDA approved antibody testing becomes available, those donors can be contacted for screening.
While the success of an experimental treatment like this will not be known for some time, history indicates it is a promising treatment option when there are no other known therapies available.