Passive immunization involves the administration of antibodies against a given agent to a susceptible individual for the purpose of preventing or treating an infectious disease due to that agent. A general principle of passive antibody therapy is that it is more effective when used for prophylaxis than for treatment of disease. When used for therapy, antibody is most effective when administered shortly after the onset of symptoms
Passive immunization involves the administration of antibodies against a given agent to a
susceptible individual for the purpose of preventing or treating an infectious disease due to
that agent. A general principle of passive antibody therapy is that it is more effective when
used for prophylaxis than for treatment of disease. When used for therapy, antibody is most
effective when administered shortly after the onset of symptoms. The reason for temporal
variation in efficacy is not well understood but could reflect that passive antibody works by
neutralizing the initial inoculums, which is likely to be much smaller than that of
established disease . As an example, passive antibody therapy for pneumococcal pneumonia was
most effective when administered shortly after the onset of symptoms, and there was no
benefit if antibody administration was delayed past the third day of disease.
Therapeutic and prophylactic significance was explored in influenza and measles . Transfusion
of immune plasma is a standard treatment modality for various viral hemorrhagic fevers . Its
efficacy in treating Ebola Virus Disease is also well established . Studies have reported
reduction viral load in patients with H1N1 influenza .Efficacy of convalescent plasma has
been anecdotally reported in SARS-CoV-2 infections .
The largest study involved the treatment of 80 patients with SARS in Hong Kong. Patients
treated before day 14 had improved prognosis defined by discharge from hospital before day
22, consistent with the notion that earlier administration is more likely to be effective .
In the case of SARS-CoV-2, the anticipated mechanism of action by which passive antibody
therapy mediated protection is viral neutralization. However, other mechanisms may be
possible, such as antibody-dependent cellular cytotoxicity and/or phagocytosis. The only
antibody type that is currently available for immediate use SARS-CoV-2 is that found in human
convalescent sera.
In China for SARS-CoV-2 disease, it has been found that the convalescent plasma therapy is
effective for patients with a disease course exceeding three weeks and whose virus nucleic
acid tests continuously to show positive from respiratory tracts specimen. It can speed up
virus clearance, increase the numbers of the plasma lymphocytes and NK cells, reduce the
level of plasma lactic acid, and improve renal functions.
Biological: convalescent plasma
Transfuse 2 aliquots of plasma (200 mL x 2) per patient.
Transfuse first aliquot for 2-3 hours (~1.4 to 2 mL/min)
Transfuse second aliquot at same rate 2 hours after completion of first aliquot
Other Name: Plasma therapy
Inclusion criteria:
- Severe or critically ill COVID-19 patients tested positive in respiratory tract test.
- The COVID-19 patients who are not severe or critically ill, but in a state of immunity
suppression;
- or have low CT values in the virus nucleic acid testing but with a rapid disease
progression in the lungs.
- Severe or immediately life-threatening COVID-19, for example,
- Severe disease is defined as one or more of the following:
- shortness of breath (dyspnea),
- respiratory frequency ≥ 30/min,
- blood oxygen saturation ≤ 93%,
- partial pressure of arterial oxygen to fraction of inspired oxygen ratio < 300,
- lung infiltrates > 50% within 24 to 48 hours
- Within 3 to 21 days from onset of symptoms
Exclusion criteria:
• Life-threatening disease is defined as one or more of the following: respiratory failure,
septic shock, multiple organ dysfunction or failure
Critically ill COVID-19 patients will not considered suitable for being transfusion as
inflammatory pathway is already set in, so antibodies will not make that much of
difference.
Muhammad Irfan Malik
Lahore, Punjab, Pakistan
Muhammad Irfan Malik, FCPS, Study Director
Post-Graduate Medical Institute, Lahore General Hospital, Lahore Pakistan