COVID-19 , caused by the novel coronavirus SARS-CoV-2, is currently a big threat to global health, and as of Sunday, the World Health Organisation reported over 28 lakh confirmed cases and close to 2 lakh confirmed deaths. Unlike bacterial or fungal infections, there are few effective medicines for viral infections. Once infected by a virus, we have to depend on the development of immunity to fight it. But the infection overwhelms some patients and becomes lifethreatening before their body can mount an effective immune response.
Thankfully, majority of the people who are infected have mild symptoms and their body does develop effective immunity in the form of antibodies which circulate in their blood. These antibodies can be collected from their blood using a widely available technique called apheresis. Plasma collected from patients who have recently recovered is called convalescent plasma. This can be given to other severely-ill patients just like a routine blood transfusion.
Convalescent plasma is a form of immunotherapy and helps patients fight the infection by boosting their immunity. However, precautions need to be taken while collecting and infusing convalescent plasma. We need to ensure that the donor has definitely recovered and does not harbour the virus. PCR testing of the donor is to be performed twice to ensure that the donor will not transmit more virus to the recipient patient. We also have to test the donor for other infectious diseases such as HIV and hepatitis to ensure that the plasma is safe for transfusion.
Parallelly, precautions are taken to ensure that the healthcare workers who are involved in the donor testing and the collection of plasma are also protected from infections. The donor is then matched to a recipient patient with cross-matching of the blood group and the plasma can then be infused. Convalescent plasma is given to patients who are seriously ill.
They are either dependent on supplemental oxygen or on the ventilator in the ICU. The convalescent plasma therapy is expected to help a good number of such critically ill patients. The therapy has been given to several patients across the world and the outcome of 15 patients, who were seriously suffering from COVID-19, has been published. All of these patients started improving in 2-3 days of infusion and a majority of them stabilised enough for them to be discharged.
Dr SACHIN JADHAV
(Group Head, Haematology and Bone Marrow Transplant, HCG)