Convalescent plasma is defined as the plasma that is extracted from the blood of a person who has recovered from a disease, and then transfused into a patient who is still battling from it.
When a person’s body is exposed to a foreign pathogen, the system produces antibodies to fight off the virus or disease. It works by binding and deactivating these invaders, preventing it from conquering the body.
Persons who have recovered from an illness tend to have a larger amount of antibodies in their system, which can linger for some time. These are contained in the plasma. Each virus is said to require its own antibodies.
During a recent engagement, Deputy Chief Medical Officer, Dr Karen Boyle had shared that Guyana is willing to be part of the clinical trials to determine if this can be used to treat the novel coronavirus, COVID-19.
“We don’t have a cure yet. The world doesn’t have a cure yet. There are some clinical trials that are taking place. In fact, Guyana is poised to possibly join some of those trials.”
On Monday, the DMO had said that a proposal was submitted to the Pan American Health Organisation (PAHO) to which the country has received a response. The DCMO believes this can aid the country’s fight against the virus, which has claimed eight lives thus far in Guyana.
Dr Boyle asserted, “That plasma would be rich in antibodies [of] people who are overcoming the disease – people who have been sick and they’re now winning the battle…”
Treatment
According to a report issued by PAHO on the “regulatory considerations on authorisation” of convalescent plasma usage, experience with the usage of these antibodies as COVID-19 treatment is “limited” but preliminary results have demonstrated “potential usefulness”.
“Several controlled clinical trials are underway, to collect more quality scientific evidence to confirm the safety and efficacy of this intervention. In this context, the recommendations foresee its use under experimental conditions within the regulatory framework of each country,” PAHO indicated.
Nevertheless, it sought to mention that challenges will arise in the large-scale collection, processing and distribution to meet potential clinical needs.
In the United States of America – which has recorded the highest coronavirus cases, antibody tests have also begun. Meanwhile, some countries have opted to issue immunity passports, allowing citizens to return to their normal social and work activities.
But the WHO contended, “At this point in the pandemic, there is not enough evidence about the effectiveness of antibody-mediated immunity to guarantee the accuracy of an “immunity passport” or “risk-free certificate.” People who assume that they are immune to a second infection because they have received a positive test result may ignore public health advice. The use of such certificates may, therefore, increase the risks of continued transmission.”
Plasma separation
For the plasma to be donated, it is first collected as a regular blood unit. However, instead of being placed in a bag, it is transferred to a centrifuge where the plasma is separated from the other components of blood.
The blood is returned to the body of the donator with a saline solution and the plasma serum is collected in a separate bag. This step is repeated until the desired amount is collected. On a normal basis, one plasma contribution can yield up to four units. This is later transferred to the patient.
In the past, this form of passive immunisation has been used to treat patients suffering from the Argentine Hemorrhagic Fever, Ebola, the H1N1 virus, the Spanish flu and other coronaviruses such as Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS).
