Plasma from donors convalescent from SARS-CoV-2 infection–A matter of priorities

A number of studies have described the transfusion of plasma, harvested from donors who have recovered from SARS-CoV-2 (COVID-19) infection, to infected patients suffering from acute illness [1], [2]. The promising results reported in these small observational studies have stimulated global interest in the organisation of collection systems for this “convalescent plasma” (CP). It is recognised that this modality's evidence base requires confirmation, and that a more standardised product for the delivery of antibodies to COVID-19 would be a hyperimmune immunoglobulin (Ig) manufactured industrially from CP, as is provided for other interventions [3]. The availability of such an Ig product would be valuable, in the first instance, in providing prophylactic protection to individuals at higher risk of acquiring COVID-19 infection, including health care workers and, if supply permits, individuals with co-morbidities. In the interim, the use of CP, if confirmed through further studies, is needed to treat patients suffering from infection. The establishment of global networks for the collection of CP, including the recent establishment of a “Plasma Coalition” bringing together a number of for-profit and not-for-profit plasma product manufacturers [4] is a commendable development in international collaboration. This plasma is intended, presumably, for the manufacture of hyperimmune Ig. This global effort, and similar systems under development within a number of countries, need to be managed carefully in order to ensure the continued supply of CP for the treatment of patients suffering from COVID-19 infection. In particular, in geographies covered by the “Plasma Coalition” [5] where paid plasma donation exists in tandem with the voluntary mainstream voluntary blood system, there is a risk that donations of CP may be deflected from the hospital based transfusion sector to the industrial environment. It is noteworthy that the manufacture of intramuscularly delivered immunoglobulins through the mainstream fractionation processes, which include hyperimmune industrial Ig, results in the loss of ca half the donated protein over the course of fractionation [6]. Until technologies which promise higher yields and which are more suited to the small volumes collected from immunised donors are available [7], [8] it is therefore preferable that the collection of CP for the treatment of patients continues unhampered until the epidemic wanes and the urgent need of transfusable CP decreases. In the interim, donor panels for hyperimmune Ig production may be constructed and an optimal path for the provision of this medicine may be developed, hopefully with harmonisation between the major regulatory agencies. This parallel path will cover the demand for treatment as well as generating hyperimmune Ig for the protection of select groups. For the general population, provision of enough Ig is unlikely and will not provide long-term protection, and hence a vaccine is eagerly awaited.

Finally, in the rapidly developing field of therapeutics to Covid-19 infection, continued vigilance is required to ensure ethical principles are maintained. Convalescent plasma harvested from voluntary donors in state blood services is at risk of being deflected from therapeutic use through preferential patient allocation to clinical trials for other Covid-19 therapies funded by large pharmaceutical companies. The evidence base of some of these therapies is nebulous, and patient allocation to such trials, which needs to include control arms, may result in disadvantage to patients [9]. Given the continued body of evidence and public effort in the collection and use of convalescent plasma, it is to be hoped that this treatment will be considered as a first line modality and will not be obstructed by commercial considerations. In particular, a transparent, publicly-driven process is required, given that mechanisms have been developed to facilitate commercial companies’ access to patients and patient organisations, a development which needs to be viewed with concern [10].

Disclosure of interest

The author declares that he has no competing interest.