Intravenous Immunoglobulins for the Treatment of Covid-19 Patients: a Clinical Trial

Emerging and re-emerging viruses are a significant threat to global public health. Since the end of 2019, Chinese authorities have reported a cluster of human pneumonia cases in Wuhan City, China and the disease was designated as coronavirus disease 2019 (COVID-19). These cases showed symptoms such as fever, dyspnea, and were diagnosed as viral pneumonia. Whole genome sequencing results show the causative agent is a novel coronavirus, which was initially named 2019-nCoV by World Health Organization (WHO). Later the International Committee on Taxonomy of Viruses (ICTV) officially designate the virus as SARS CoV-2 (Coronaviridae Study Group of the International Committee on Taxonomy of Viruses, 2020), although many virologists argue that HCoV-19 is more appropriate . As of 24 February 2020, 79,331 laboratory-confirmed cases have been reported to the WHO globally, with 77,262 cases in China, including 2,595 deaths. In addition, twenty-nine other countries have confirmed imported cases of SARS-CoV-2 infection raising great public health concerns worldwide. SARS-CoV-2 represents the seventh coronavirus that is known to cause human disease. Coronaviruses (CoVs) are a group of large and enveloped viruses with positive sense, single-stranded RNA genomes. Previously identified human CoVs that cause human disease include severe acute respiratory syndrome coronavirus (SARS-CoV), and Middle East respiratory syndrome coronavirus (MERS-CoV) . SARS-CoV and MERS-CoV infection can result in life threatening disease and have pandemic potential. During 2002-2003, SARS-CoV initially emerged in China and swiftly spread to other parts of the world, causing > 8,000 infections and approximately 800 related deaths worldwide. In 2012, MERS-CoV was first identified in the Middle East and then spread to other countries. As of November 2019, a total of 2,494 MERS cases with 858 related deaths have been recorded in 27 countries globally. Notably, new cases of MERS-CoV infecting humans are still being reported recently. Both SARS-CoV and MERS-CoV are zoonotic pathogens originating from animals. Detailed investigations indicate that SARS-CoV is transmitted from civet cats to humans and MERS-CoV from dromedary camels to humans. The source of SARS-CoV-2, however, is still under investigation, but linked to a wet animal market. There is no specific antiviral treatment recommended for COVID-19, and no vaccine is currently available. The treatment is symptomatic, and oxygen therapy represents the major treatment intervention for patients with severe infection. Mechanical ventilation may be necessary in cases of respiratory failure refractory to oxygen therapy, whereas hemodynamic support is essential for managing septic shock. Although no antiviral treatments have been approved, several approaches have been proposed such as lopinavir/ritonavir (400/100 mg every 12 hours), chloroquine (500 mg every 12 hours), and hydroxychloroquine (200 mg every 12 hours). Alpha-interferon (e.g., 5 million units by aerosol inhalation twice per day) is also used. Preclinical studies suggested that remdesivir (GS5734) - an inhibitor of RNA polymerase with in vitro activity against multiple RNA viruses, including Ebola - could be effective for both prophylaxis and therapy of HCoVs infections. This drug was positively tested in a rhesus macaque model of MERS-CoV infection. One dose of 200 mL convalescent plasma (CP) derived from recently recovered donors with the neutralizing antibody titers above 1:640 was transfused to the patients as an addition to maximal supportive care and antiviral agents. Despite a lack of completed clinical trials, the FDA has granted this temporary authorization under its Investigational New Drug Applicants (eINDS) exemption, in light of the extent and nature of the current public health threat that COVID-19 represents. A number of pre-clinical and clinical trials around use of plasma from patients who have recovered are underway, however, and there are some promising signs that convalescent plasma could indeed be effective against SARS-CoV-2.

Apart from convalescent plasma, small scale concentrates of immunoglobulins prepared from convalescent plasma collections provide higher potency and greater consistency than individual units. The feasibility of production of large scale of diseases specific immunoglobulins concentrates can considered for longer term, based on the course of epidemic, access to large numbers of suitable plasma collections, and the available infrastructure for manufacturing such products under GMP.

• Convalescent plasma can be used for serum therapy but it has further limitations which include:

• Separate plasma for separate blood groups: In case of plasma, it seems difficult to arrange the required blood groups separately for serum therapy, while immunoglobulins can be injected randomly to individual of different blood groups.
• Serum Sickness & Blood Proteins reactogencity: Only 18% of plasma constitutes immunoglobulins required for passive immunization. Remaining portions contain proteins that pose to reactogenicity threat to patient safety.
• Dose volume: In case of plasma therapy, 200-300ml of plasma required for single patient that depends upon number of recovered patients available. While in case of immunoglobulins used in virus therapy require only 3-5ml per day.
• Risk of microbial contamination: As most portion of plasma contain proteins and proteins are more prone to contamination risk. It is difficult to handle the serum to maintain its sterility while immunoglobulins are far less prone to sterility issues.
• Potency: Concentrated immunoglobulins are far more potent as it shows targeted response. In case of plasma, proteins fractions pose a delayed response.
• Targeted Population: Plasma therapy is subjected to moderate to severe patients specially, while all effected individuals can take benefit of immunoglobulin therapy because dose of immunoglobulins can be controlled.