Covid-19 death rate could be lowered among sickest patients using blood plasma treatment, says Hong Kong university expert

Zoe Low
·4-min read

The death rate among the sickest Covid-19 patients could be lowered by treating them using blood plasma with high levels of antibodies donated by those who have recovered from the virus, a local infectious diseases expert has said.

Out of 50 critically ill patients across the city who received convalescent plasma treatment, only 11 mostly elderly patients died, while 30 recovered, said Professor Ivan Hung Fan-ngai, a clinical professor of medicine at the University of Hong Kong.

“This treatment can help patients, who have received it quickly, fight off and clear out the virus from their system, as well as regulate the patients’ immune systems,” Hung said.

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He said the most important function of the treatment was to clear out the virus, which would prevent further complications such as organ failure.

“This will help lower the death rate and increase recovery rate among patients,” he said.

Side effects from plasma were rare, Hung said, although some people could develop allergies or heart failure if the body was unable to handle processing the 500ml of plasma required for treatment.

Since the pandemic broke out early this year, the city has seen 5,303 cases, with 105 related deaths.

In Hong Kong, use of the treatment derived from the antibody-rich plasma – the pale yellow liquid left behind after removing red and white cells from blood – has been ongoing since May. It is only used on patients in intensive care who need ventilators to help them breathe.

The Food and Drug Administration in the US has also authorised the use of plasma treatments for emergency situations, although the decision was contested by a group of top health officials including Dr Anthony Fauci because clinical trials had not proved the treatment was safe.

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On Thursday, the British Medical Journal published an Indian randomised trial which found convalescent plasma was not associated with a reduced rate of progression to severe Covid-19 or mortality.

An earlier study of 35,000 people by the Mayo Clinic found patients receiving transfusions within three days of their diagnosis had a seven-day rolling average death rate of 8.7 per cent, while those receiving it four or more days later had a death rate of 11.9 per cent.

Hung said doctors would consider giving patients convalescent plasma if their condition continued to worsen, even after being treated with antiviral drugs such as interferon, and steroids.

“The earlier we can give them the plasma the better, but we would usually look at the effect of other treatments as well,” he said.

Most patients only required one injection before making a recovery within a week, with two of the 50 patients requiring two transfusions before being able to be taken out of intensive care. Hung said one patient at Queen Mary Hospital, in Pok Fu Lam, had to be given two treatments as her lungs still showed signs of inflammation after the first injection.

Within two weeks of the second treatment, she was discharged from the intensive care unit and no longer required breathing support.

“Now she can easily walk up to two to three flights of stairs and is basically 70 to 80 per cent recovered,” Hung said.

However, he said use of plasma also needed to be carefully considered as the city only had enough blood left to treat another 40 or so patients.

“Ideally we hope we can have enough in store to treat up to 70 people, but that is also dependent on the number of suitable donors,” he said.

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Donors needed to meet a specific set of criteria, with levels of the neutralising antibody titre reaching more than 1:80 to be eligible to donate plasma, usually patients who had more severe forms of the illness.

They must also be males aged between 18 and 60, must not have any pre-existing conditions such as diabetes, liver or heart disease, and must not be carrying any Aids antibodies. They also cannot donate plasma if they are underweight or have fine capillaries.

Women were excluded from the donor pool as they would have to test negative for human leucocyte antigen, an antibody usually formed during pregnancy which regulates the immune system, but could cause lung injuries to recipients of blood transfusions.

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