Over the years, we’ve broached the subject of plasma therapy a time or two, mostly in regards to attempts by Chinese doctors to treat H5N1 infections. Early results have been promising.
The idea isn’t new.
In fact, it was central to what was arguably the first controlled clinical trial, Fibiger’s trial of serum treatment of Diphtheria, dating back to 1898.
Later, during the great pandemic of 1918, serum treatments were tried, but the results were often disappointing.
The process is actually fairly simple.
Blood is collected from those who been infected, and have recovered, and through a process called plasmapheresis, the blood cells are removed from the blood plasma.
This is done by passing the blood through a special filter, or by using a centrifuge. The remaining blood plasma will contain antibodies that could then be injected into severely ill patients.
Convalescent plasma could, theoretically, be used as either a treatment for someone already infected, or as a temporary prophylactic, to prevent infection.
There is more to it, of course.
The donor must be checked for a variety of blood borne diseases (i.e. hepatitis B, hepatitis C, Syphilis, and HIV), and then the plasma is usually heated to inactivate other possible pathogens.
One of the earliest reports I can find on China’s use of plasma to treat bird flu dates back to March of 2007 (see China Using Human Serum to Treat H5N1).
Six months later, an article appeared in the NEJM on China’s early success with serum treatment of H5N1 (see Human Serum For Bird Flu?). And the following year, we got more details on two patients who received this experimental treatment and recovered (see Clinical Case Review Of 26 Chinese H5N1 Patients).
In December of 2009, Shanghai health officials began asking for blood donations from those who had recovered from the pandemic H1N1 virus (see Shanghai: Serum Treatment For H1N1) in order to produce serum.
First, excerpts from the Press release, then a link to the study.
Convalescent plasma therapy—using plasma from patients who have recovered from an infection to treat those with the same infection—has been used to treat multiple diseases. However, the efficacy of this treatment in patients with severe 2009 H1N1 influenza is unknown. A study published in the February 15 issue of Clinical Infectious Diseases suggests that convalescent plasma may reduce the death rate in patients severely ill with this type of influenza. (Please see below for a link to the embargoed study online.)
From September 2009 through June 2010, patients from a hospital cluster in Hong Kong with severe 2009 H1N1 infection requiring intensive care were recruited for the study. Of the 93 patients in the study, 20 received the plasma treatment. Prior patients who had recovered from H1N1 infection provided the convalescent plasma for the study. The 73 members of the study who declined the treatment were the study controls.
Mortality in the treatment group was 20 percent, compared to 55 percent in the non-treatment group. The viral load in the treatment group also decreased at a higher rate than in the control group. None of the patients developed adverse events from the treatment.
"One of the benefits of convalescent plasma treatment in patients with severe influenza A infection is that it does not suffer from the problem of drug resistance," said study author Kowk-Yung Yuen, MD, of the University of Hong Kong in China. "Additionally, it would remain effective until the virus has changed significantly enough to affect immunity. This form of treatment may be useful in future novel viral infections."
While a 20 percent mortality rate among those receiving plasma therapy may seem extraordinarily high, only patients that were already critically ill were offered this experimental treatment.
And 55% of those declining the treatment died.
You can read the entire study by following the link below.
Ivan FN Hung, Kelvin KW To, Cheuk-Kwong Lee,Kar-Lung Lee, Kenny Chan, Wing-Wah Yan, Raymond Liu,Chi-Leung Watt, Wai-Ming Chan, Kang-Yiu Lai,Chi-Kwan Koo, Tom Buckley,Fu-Loi Chow,Kwan-Keung Wong, Hok-Sum Chan, Chi-Keung Ching, Bone SF Tang,Candy CY Lau,Iris WS Li, Shao-Haei Liu, Kwok-Hung Chan, Che-Kit Lin, and Kwok-Yung Yuen
* * * * * *
Note: The words `plasma’ and `serum’ have often been used interchangeably in earlier reports on these Chinese experimental treatments.
While similar, these two blood products are not exactly the same.
Serum = Plasma – clotting factors (fibrinogen)
A trivial enough point, I suppose. But one I thought I’d mention before one of my sharp-eyed readers brought it up.
Today’s study refers to convalescent plasma, and makes no specific mention of the removal of clotting factors.