Sarah Chapman blogs about a Cochrane A rapid review is a simplified systematic review that can be done in a few weeks to produce timely evidence for decision-making. More produced in response to the COVID-19 pandemic, looking at the evidence on convalescent plasma as a possible treatment for COVID-19. This blog discusses a A Living Systematic Review is a systematic review which is continually updated, incorporating relevant new evidence as it becomes available. More, which was last updated on 20th May 2021.
Page last updated 21 June 2021.
With an urgent need for evidence to help those making health decisions in these unparalleled times, one of the things Cochrane is doing in response is to produce rapid reviews. These are simplified In systematic reviews we search for and summarize studies that answer a specific research question (e.g. is paracetamol effective and safe for treating back pain?). The studies are identified, assessed, and summarized by using a systematic and predefined approach. They inform recommendations for healthcare and research. More that can be done in a few weeks to produce timely evidence for decision-making. The latest of these, updated on 20th May 2021, brings together the evidence on convalescent plasma as a possible treatment for people with COVID-19.
What is convalescent plasma?
Plasma is a liquid that makes up about half of your blood volume. After a person has recovered from an infection (this is the convalescent bit), their blood contains antibodies that help fight infection. Some people who have fully recovered from an infection can donate plasma (as with blood donation, there are reasons why they might not be able to). Randomized trials are being done to investigate the potential benefits or harms of using plasma from people who have recovered from COVID-19 to treat people who are currently ill with it.
Convalescent plasma has been used in the past to effectively treat infections where there were no drug treatments or vaccines, such as diptheria and polio. Evidence on whether it helps treat severe respiratory infections has been mixed and there are potential harms too, such as allergic reactions.
This has led some researchers to consider plasma as a potential Something done with the aim of improving health or relieving suffering. For example, medicines, surgery, psychological and physical therapies, diet and exercise changes. More for COVID-19, but we need to know what evidence there is on the benefits and risks.
What is the evidence from the Cochrane Rapid Review?
The review authors looked for studies investigating convalescent plasma or hyperimmune immunoglobulin (prepared from convalescent plasma) for people with COVID‐19, without any limits on age, ethnicity, gender or disease severity.
The latest news (20 May 2021)
This review is being updated as a ‘living systematic review’. The authors search for new evidence every week and update the review when they identify relevant new evidence.
In May 2021, the review was updated for the fourth time. Thankfully, we now have much more reliable evidence than we had previously. The review now includes 13 studies with 48,509 participants, of whom 41,880 received convalescent plasma. Twelve of these studies are Randomization is the process of randomly dividing into groups the people taking part in a trial. One group (the intervention group) will be given the intervention being tested (for example a drug, surgery, or exercise) and compared with a group which does not receive the intervention (the control group). More A trial in which a group (the ‘intervention group’) is given a intervention being tested (for example a drug, surgery, or exercise) is compared with a group which does not receive the intervention (the ‘control group’). More – the most reliable form of An investigation of a healthcare problem. There are different types of studies used to answer research questions, for example randomised controlled trials or observational studies. More. All but one of the studies included participants with moderate to severe COVID‐19. The studies mainly took place in hospitals, in countries all over the world. The review authors only found studies that investigated plasma – none investigated hyperimmune immunoglobulin.
Plasma as a treatment for people with moderate to severe COVID‐19
Compared to An intervention that appears to be the same as that which is being assessed but does not have the active component. For example, a placebo could be a tablet made of sugar, compared with a tablet containing a medicine. More or standard care, convalescent plasma makes little to no difference to:
- the chance of dying from any cause up to 28 days after treatment.
- the improvement of patients’ condition in terms of needing less breathing support, neither for people needing any breathing support before the start of treatment, nor for the people who were ventilated at the beginning of the study.
- the worsening of patients’ condition.
Convalescent plasma may make little to no difference to unwanted effects. However, only eight studies reported unwanted effects and they measured and reported their results very differently, so there is still uncertainty about potential harms.
None of the studies reported information about quality of life.
Plasma as a treatment for people with mild COVID‐19
The review authors only found one study with 160 participants that assessed people with mild COVID‐19. As such, the potential benefits and risks of plasma as a treatment for people with mild COVID-19 remain uncertain.
Increasing certainty that plasma has little to no benefit for treating people with moderate to severe COVID-19
The latest update of this review has brought increasing certainty. We can now be confident that convalescent plasma has little or no benefit as a treatment for people with moderate to severe COVID‐19. However, the effects of convalescent plasma for treating people with mild COVID‐19 or who have no symptoms remain uncertain.
More studies under way…
The authors found about 130 ongoing, unpublished and recently published studies. They will update the review with evidence from these studies as soon as possible. Hopefully, new evidence may answer the remaining questions.
There is a Cochrane Clinical Answer for this Review: What are the effects of convalescent plasma for people with moderate to severe COVID‐19?
On this page, which is constantly updated, you can stay informed about Cochrane content relating to the coronavirus (COVID-19) pandemic and the various related activities that Cochrane is undertaking in response.
Join in the conversation on Twitter with @CochraneUK @SarahChapman30 or leave a comment on the blog. Please note, we cannot give medical advice and we will not publish comments that link to commercial sites or appear to endorse commercial products.
Piechotta V, Iannizzi C, Chai KL, Valk SJ, Kimber C, Dorando E, Monsef I, Wood EM, Lamikanra AA, Roberts DJ, McQuilten Z, So-Osman C, Estcourt LJ, Skoetz N. Convalescent plasma or hyperimmune immunoglobulin for people with COVID‐19: a living systematic review. Cochrane Database of Systematic Reviews 2021, Issue 5. Art. No.: CD013600. DOI: 10.1002/14651858.CD013600.pub4. https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD013600.pub4/full
Cochrane. Updated Cochrane living review investigates the use of convalescent plasma to treat people with COVID-19. Cochrane.org, 20 May 2021. Web. 26 May 2021. Available from: https://www.cochrane.org/news/updated-cochrane-living-review-investigates-use-convalescent-plasma-treat-people-covid-19
Sarah Chapman has nothing to disclose.