The convalescent sera option for containing COVID-19

With a vaccine for COVID-19 still a long way from being realized, Johns Hopkins University is working to revive a century-old blood-derived treatment in hopes of slowing the spread of the disease.



Even at their most effective – and draconian – containment strategies have only slowed the spread of the respiratory disease Covid-19. With the World Health Organization finally declaring Covid-19 a pandemic, all eyes have turned to the prospect of a vaccine, because only a vaccine can prevent people from getting sick. About 35 companies and academic institutions are racing to create such a vaccine, at least four of which already have candidates they have been testing in animals. The first of these – produced by Boston-based biotech firm Moderna. Human trials, skipping animal testing, with a potential corona vaccine have already begun – but even if they go well and a cure is found, there are many barriers before global immunisation is feasible. Traditionally, immunisation has been achieved using live, weakened forms of the virus, or part or whole of the virus once it has been inactivated by heat or chemicals. These methods have drawbacks. The live form can continue to evolve in the host, for example, potentially recapturing some of its virulence and making the recipient sick, while higher or repeat doses of the inactivated virus are required to achieve the necessary degree of protection.



Arturo Casadevall, an immunologist at Johns Hopkins University in Baltimore, Maryland, has been fighting to use blood as a COVID-19 treatment since late January, as the disease spread to other countries and no imminent therapy was in sight. Scientists refer to this measure as ‘passive antibody therapy’ because a person receives external antibodies, rather than generating an immune response themselves, as they would following a vaccination. The approach dates back to the 1890s. One of the largest case studies occurred during the 1918 H1N1 influenza virus pandemic. More than 1,700 patients received blood serum from survivors, but it’s difficult to draw conclusions from studies that weren’t designed to meet current standards. A key advantage to convalescent plasma is that it’s available immediately, whereas drugs and vaccines take months or years to develop. Infusing blood in this way seems to be relatively safe, provided that it is screened for viruses and other infectious agents. Scientists who have led the charge to use plasma want to deploy it now as a stopgap measure, to keep serious infections at bay and hospitals afloat as a tsunami of cases comes crashing their way.



As of early 2020, humanity is confronting a pandemic in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). SARS-CoV-2 causes coronavirus disease, abbreviated as COVID-19. At the time of this writing, SARS-CoV-2 is spreading in multiple countries, threatening a pandemic that will affect billions of people. This virus appears to be a new human pathogen. Currently there are no vaccines, monoclonal antibodies (mAbs), or drugs available for SARS-CoV-2, although many are in rapid development and some may be available in a short time. This Viewpoint argues that human convalescent serum is an option for prevention and treatment of COVID-19 disease that could be rapidly available when there are sufficient numbers of people who have recovered and can donate immunoglobulin-containing serum.


A. Casadevall and L Pirofski. The convalescent sera option for containing COVID-19. Nature Protocols. J. Clin. Invest. (2020)