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Convalescent plasma: A promising old therapeutic approach

Coronavirus disease 2019 (COVID-19), an acute respiratory disease whose outbreak has been declared a pandemic, infected more than 1.2 million people worldwide, killed 69,498 and 2,65,883 were recovered (as of Apr 6, 2020).1

Any approved vaccines or therapies for COVID-19?

As of now, there are no Food and Drug Administration (FDA) -approved vaccines or therapies for COVID-19, although the U.S. regulators on March 29 approved limited emergency use for chloroquine and hydroxychloroquine to treat COVID-19 patients.2 Infected patients should receive supportive care to help alleviate symptoms. Favilavir, an anti-viral drug is the first approved coronavirus drug in China, though FDA has not regarded it as an effective treatment for coronavirus. Currently, about 35 companies and academic institutions are racing to create a vaccine.3 Given the dearth of treatments for COVID-19, convalescent plasma seems to be a promising option to try.

What is convalescent plasma?

The blood plasma extracted from an animal or human patient who has “convalesced” or recovered from infection with a particular disease is known as convalescent plasma. This is a passive antibody therapy in which the body does not create its own antibodies, but instead “borrows” them. It can greatly reduce time to recover, however, unlike vaccine, their protection does not last long. History suggests that since 1892, convalescent plasma has always been used when confronted with infectious diseases and outbreaks. In recent years, plasma therapy has been used to treat victims of Ebola, SARS and H1N1 influenza.4

U.S needs plasma from COVID-19 survivors now as FDA grants permission

1. On Mar 27, 2020, Chinese researchers reported that convalescent plasma appeared to help Covid-19 patients on ventilation5

2. Mar 24, 2020, the FDA allowed use of COVID-19 convalescent plasma for severely ill patients under single-patient emergency Investigational New Drug Applications (INDs). This does not include its use for the prevention of infection6

3. Table 1 shows the worldwide ongoing clinical studies of convalescent plasma use in COVID-19 treatment

Table 1

Registered numberSponsorCondition (Patient pool)Phase/StatusStart date/
Primary completion date
NCT04332835Del Rosario UniversityCOVID-19 (Adults)Phase 2/3/ Not yet RecruitingApr-2020/Aug-2020Colombia
NCT04323800SKCC, Johns HopkinsCOVID-19 (Adults)Phase 2/Not yet RecruitingApr-2020/Dec-2022
NCT04325672Mayo ClinicAcute respiratory symptoms due to COVID-19 (Adults)Phase 2/ Not yet RecruitingApr-2020/Dec-2022U.S.
NCT04333251Baylor Research InstituteInterstitial Pneumonia due to COVID-19 (Adults)Phase 1/Not yet RecruitingApr-2020/Dec-2022
NCT04333355San Jose Tec de Monterrey HospitalCOVID-19 (Adults)Phase 1/Not yet RecruitingApr-2020/Dec-2020Mexico
NCT04292340Shanghai Public Health Clinical CenterCOVID-19 Pneumonia (All ages)RecruitingFeb-2020/Jul-2020China
NCT04327349Mazandaran University of Medical SciencesCOVID-19 (30-70 years)Not Applicable/Enrolling by InvitationMar-2020/May-2020Iran

Key players in the pharma industry have also initiated developments to use COVID-19 convalescent plasma

Companies using convalescent plasma in the pursuit of COVID-19 treatment Developments
Grifols• Mar 25, 2020, Grifols entered a collaboration with Biomedical Advanced Research and Development Authority (BARDA), FDA and other Federal public health agencies to collect COVID-19 convalescent plasma and support preclinical and clinical studies to determine if anti-SARS-CoV-2 H-IG therapy can successfully be used to treat COVID-19 disease
• Grifols is providing viral inactivation technology to support utilization of convalescent plasma for transfusion7
CSL, Takeda, Octapharma, Biotest, Bio Products Laboratory (BPL), LFBApr 6, 2020, global plasma companies collaborated to develop anti-SARS-CoV-2 polyclonal H-IG medicine with the potential to treat individuals with serious complications from COVID-198
Emergent BioSolutions BiotherapeuticsThey are using convalescent plasma to develop 2 different kinds of treatments, one based on horse-derived plasma and other human-derived plasma9

Will this old age therapy give new life to COVID-19 patients without any hurdles?

In the case of COVID-19, the potential risks of receiving convalescent plasma remain unknown. The possibility of being introduced with unknown pathogens and transfusion reactions while receiving this treatment is also an important point to be investigated. For dengue virus, being treated with convalescent serum makes the patient’s condition worse, as it causes the virus to replicate.

Although the study on 5 patients with COVID-19 treatment reported good results, however, it was unclear if patients would have improved without the use of convalescent plasma, as they were treated with multiple other agents, including antiviral medications. Hence, further evaluation in clinical trials is necessary.5

As of now we have less recovered patients and a single plasma donation from a COVID-19 survivor could treat 2-3 patients. But most of these interested donors will not be suitable for one reason or another:

1. The criteria, set by the FDA, suggest that donors must have had proven COVID-19 infection and have been shown to be recovered

2. Female donors must be negative for HLA antibodies

3. Suitable donors will not be selected unless they have had a documented infection that began 28 days before they can donate plasma as they seem to increase anti-body titer around day 28

As a U.S. vaccine is 18 months off, effective treatments still unidentified, the use of convalescent plasma seems to be promising for now.10


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