Sarah Chapman highlights Cochrane evidenceCochrane Reviews are systematic reviews. 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 on COVID-19 and other health effects of the pandemic, with links to reviews, blogs and other Cochrane resources.
This blog was last updated on 26 July 2021.
While we’ve all been adapting to huge and sudden changes in our lives and healthcare workers have been meeting unprecedented challenges, scientists have scrambled to produce research evidence relevant to the pandemic. Cochrane is responding by producing rapid reviews of this new evidence on priority topics, and these are updated as new evidence emerges. They show that much of the research that has been done so far leaves us with more unanswered questions than answers, but we must hope that this changes as new studies are available to add to the reviews.
Here’s a round-up of some of the Cochrane evidence so far. On this page, there are sections on:
- Detecting COVID-19
- Measures to control the spread of COVID-19
- Treating people with COVID-19
- The impact of the pandemic on other areas of health and wellbeing
- Coronavirus (COVID-19): Special Collections
- Coming up…
Detecting COVID-19
Signs and symptoms of COVID-19
We’re hearing a lot about temperature checks, which in many places are being used determine whether someone may enter a care home, hairdressers or other building. But what’s the evidence? We’ve blogged about a Cochrane Review, first published in July 2020 and updated in February 2021, on the accuracy of any signs and symptoms, either alone or in combination, for diagnosing COVID‐19.
You can read the blog: “Signs and symptoms of COVID-19: new Cochrane evidence“. There is also a podcast.
Antibody tests for COVID-19
Antibody tests have the potential to identify people who have had COVID-19. A Cochrane Review ‘Antibody tests for identification of current and past infection with SARS-CoV-2′ was published in June 2020 and we have blogged about it: “Antibody tests for COVID-19: new evidence on test accuracy and some considerations“.
Rapid point-of-care tests for diagnosing COVID-19 infection
Tests for diagnosing COVID-19 infection are important tools for helping reduce the spread of infection in communities, schools and workplaces, and have received a huge amount of attention in the press and on social media over the last year. The Cochrane Review Rapid, point‐of‐care antigen and molecular‐based tests for diagnosis of SARS‐CoV‐2 infection, was updated for the first time in March 2021. The review looks at two types of test, antigen tests (including lateral flow tests or LFTs) and molecular tests. Both types of test use swab samples taken from the nose or throat, can be used outside of a specialist laboratory and provide results in less than two hours.
Lead author, Jac Dinnes, has written a blog Rapid point-of-care tests for diagnosing COVID-19 infection: the latest Cochrane evidence to help health care professionals and members of the public interpret the evidence for their accuracy.
Routine laboratory tests – how good are they for detecting COVID-19?
Routine blood tests, processed in laboratories, include counts of different types of white blood cells that help fight infection and identifying proteins (‘markers’) that can indicate general inflammation and organ damage. These are widely available and in some places might be the only tests available for diagnosing COVID-19.
A Cochrane Review Routine laboratory testing to determine if a patient has COVID‐19 (November 2020) has looked for evidence on the accuracy of these tests in people with suspected COVID-19 for diagnosing the disease and for prioritizing people for different levels of treatmentSomething done with the aim of improving health or relieving suffering. For example, medicines, surgery, psychological and physical therapies, diet and exercise changes. More. The review includes 21 studies looking at 67 routine laboratory tests for COVID-19, all in people who were patients in hospitals.
The bottom line: “Although these tests give an indication about the general health status of patients and some tests may be specific indicators for inflammatory processes, none of the tests we investigated are useful for accurately ruling in or ruling out COVID‐19 on their own.”
Screening for COVID-19
Screening people who have mild or no symptoms but have COVID-19, to find out if someone’s infected, is another strategy that has potential to help reduce the spread of infection, as those who are found to have the virus could then isolate, for example. A Cochrane rapid reviewA rapid review is a simplified systematic review that can be done in a few weeks to produce timely evidence for decision-making. More on universal screening for SARS‐CoV‐2 infection was published in September 2020. The evidence base is currently very limited and highlights uncertainty about the effectivenessThe ability of an intervention (for example a drug, surgery, or exercise) to produce a desired effect, such as reduce symptoms. More of screening for COVID-19. The review finds that:
“One‐time screening in apparently healthy people is likely to miss people who are infected. We are unsure whether combined screenings, repeated symptom assessment, or rapid laboratory tests are useful.
As more people become infected, screening will identify more cases. However, because screening can miss people who are infected, public health measures such as face coverings, physical distancing, and quarantine for those who are apparently healthy, continue to be very important.”
Here is a video summary.
Thoracic (chest) imaging tests for COVID-19
A Cochrane Review on thoracic imaging tests for the diagnosis of COVID-19 was published in September 2020 and updated for a second time in March 2021. It brings together evidence on the diagnostic accuracy of chest (thoracic) imaging (computed tomography (CT), X‐ray and ultrasound) in people with suspected COVID‐19. This is one of a suite of Cochrane ‘living systematic reviews’ summarising evidence on the accuracy of different imaging tests and diagnostic features in people regardless of their symptoms, grouped according to the research questions and settings.
The review includes 51 studies involving 19,775 people with suspected COVID-19, of whom just over half had a final diagnosis of COVID-19. Most of the studies looked at chest CT. The evidence so far suggests that chest CT is better at ruling out COVID-19 infection than distinguishing it from other respiratory problems. So, its usefulness may be limited to excluding COVID‐19 infection rather than distinguishing it from other causes of lung infection. However, the authors’ confidence in the evidence is limited because the studies differed from each other, used different methods to report their results and and very few studies directly compared one type of imaging test with another.
Measures to control the spread of COVID-19
School-based measures to contain the COVID-19 pandemic
Shutting schools was one of the earliest responses to the pandemic in many countries. As well as potential benefits of this strategy for limiting the spread of infection there are many potential harms, including worsening health and wellbeing for children and widening inequalities. Alternatives to school closure are also being adopted, including the wearing of face masks, hand hygiene, changes to school activities, improved ventilation systems and screening. It will be important to have evidence of the effectiveness of these different measures to inform policy and practice.
Cochrane has published a scoping reviewExploratory projects that systematically map the literature available on a topic, identifying key concepts, theories, sources of evidence and gaps in the research. More on measures implemented in the school setting to contain the COVID‐19 pandemic (December 2020), to map the existing evidence. The review authors found 42 studies, of which 31 were mathematical modelling studies, evaluating a wide range of measures. This will form the basis of a review of the effectiveness of these measures.
Quarantine for controlling COVID-19
A Cochrane rapid review on quarantine alone or in combination with other public health measures to control COVID-19 was published in April 2020 and updated in September 2020. It is the focus of this blog: “Quarantine for controlling COVID-19 (coronavirus). New Cochrane evidence.”
Watch a video of the lead author summarising the review’s findings. You might also be interested in this blog ““Stay at home” rules: what makes people more likely to stick to quarantine?“, which looks at two non-Cochrane rapid reviews from researchers at King’s College London.
Contact tracing
Contact tracing aims to reduce transmission of infection by identifying people who have been in contact with someone who has it, so that they can isolate. A Cochrane rapid review published in August 2020 looked at evidence on digital contact tracing technologies in epidemics.
The review highlights an evidence gap, the authors concluding that “the effectiveness of digital solutions is largely unproven as there are very few published dataData is the information collected through research. More in real‐world outbreak settings.”
Personal Protective Equipment (PPE) for healthcare workers
Two Cochrane reviewsCochrane Reviews are systematic reviews. 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 contribute to the evidence base on PPE for healthcare workers and we have a blog about these: “Personal protective equipment (PPE) for healthcare workers: new Cochrane evidence“. They look at Personal protective equipment for preventing highly infectious diseases due to exposure to contaminated body fluids in healthcare staff (May 2020) and Barriers and facilitators to healthcare workers’ adherence with infection prevention and control (IPC) guidelines for respiratory infectious diseases: a rapid qualitative evidence synthesis (April 2020).
For the review on PPE there is a Cochrane Clinical Answer. For the review on barriers and facilitators there is podcast and a Cochrane Clinical Answer. Evidence Synthesis Ireland and Cochrane Ireland have also created an infographic summarising key messages.
Antimicrobial mouthrinses and nasal sprays to protect healthcare workers and patients at risk of COVID-19
Antimicrobial mouthrinses and nasal sprays have the potential to help people with COVID-19 fight infection and prevent them infecting healthcare workers who care for them. They might also offer some protection to healthcare workers, especially if they use them before doing aerosol-generating procedures, such as drilling teeth.
Three new Cochrane Reviews were published in September 2020 looking at different aspects of this. There is a helpful summary of all three in this Cochrane Oral Health Editorial base blog Antimicrobial mouthrinses and nasal sprays to protect healthcare workers and patients at risk of COVID-19, which also has links to each of the reviews. No completed studies were found for any of the reviews, so this is currently an evidence gap, but there are ongoing studies for two of these three reviews and all will be updated.
Travel-related measures
A Cochrane rapid review, published in September 2020, looked at travel-related control measures to contain the COVID-19 pandemic. Not surprisingly, it highlighted uncertainty about their effectiveness and a lack of reliable and ‘real-life’ evidence. The review was updated in March 2021.
Jacob Burns, lead author of this update explains, “In this update we identified a much expanded evidence base related to international travel control measures to contain the COVID-19 pandemic, with 38 additional studies focusing on COVID-19 identified. Many of the studies were similar with regard to scope and methods, and overall the conclusions of the updated review remain largely the same. Some aspects of the evidence base, however, were improved – for example, we identified studies from further parts of the world that were not represented in the original review, including African and Eastern Mediterranean regions. Additionally, we identified more studies evaluating entry and/or exit screening measures at real-world ports of entry.”
You can read about the review in this blog “Travel-related measures for controlling the spread of COVID-19: New Cochrane evidence“.
Treating people with COVID-19
Cardiovascular effects
A Cochrane Review COVID‐19 and its cardiovascular effects: a systematic review of prevalence studies (March 2021) has looked at both cardiovascular problems pre-existing the development of COVID-19 and assesses the riskA way of expressing the chance of an event taking place, expressed as the number of events divided by the total number of observations or people. It can be stated as ‘the chance of falling were one in four’ (1/4 = 25%). This measure is good no matter the incidence of events i.e. common or infrequent. More of cardiovascular complications, highlighting which are the most common (unexpectedly, this was atrial fibrillation). Senior author Professsor John GF Cleland discusses it in this interview. He comments that “These results show what the clinical teams looking after patients with COVID should watch out for. Clinical teams are already aware of the risk of blood clots but may be less aware of the risk of developing atrial fibrillation or heart failure. Also, heart failure may be difficult to diagnose in a patient with COVID, so great care and attention is required not to miss this treatable diagnosis. ”
There is a Cochrane Clinical Answer for this review: “What are the cardiovascular effects of COVID-19?” and a Cochrane Podcast: What type of heart and blood vessel problems complicate COVID-19 infections, how common are they and what other medical conditions do these patients have?.
Convalescent plasma – a possible treatment for COVID-19?
Many clinical trialsClinical trials are research studies involving people who use healthcare services. They often compare a new or different treatment with the best treatment currently available. This is to test whether the new or different treatment is safe, effective and any better than what is currently used. No matter how promising a new treatment may appear during tests in a laboratory, it must go through clinical trials before its benefits and risks can really be known. More 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. This blog: “Convalescent plasma to treat people with COVID-19: the evidence so far” looks at a Cochrane rapid review on convalescent plasma to treat people with COVID-19, updated for the fourth time in May 2021. There is now high-certainty evidence that convalescent plasma has little to no benefit for the treatment of people with moderate to severe COVID‐19. You can also read an interview with Vanessa Piechotta, the lead author of the review.
Oxygen therapy for adults in intensive care with acute respiratory distress syndrome
A Cochrane rapid review on oxygen targets in the intensive care unit during mechanical ventilation for acute respiratory distress syndrome has brought together evidence on this topic. The review authors explain the context:
“AcuteA health condition (or episodes of a health condition) that comes on quickly and is short-lived. More respiratory distress syndrome (ARDS) is a very severe breathing problem with a high mortalitydeath More rateThe speed or frequency of occurrence of an event, usually expressed with respect to time. For instance, a mortality rate might be the number of deaths per year, per 100,000 people. More (chance of dying). It has many potential causes, including viral infections such as COVID‐19, and there are no specific treatments for it except for giving patients oxygen via a ventilator (artificial breathing machine) on an intensive care unit, often for long periods of time. However, large amounts of oxygen (either a high concentration of oxygen or oxygen administered for a long period of time) are associated with increased harm due to other illnesses (e.g. heart attack or stroke).”
Here’s what they found:
You may also be interested in recent Cochrane Reviews on High versus low positive end‐expiratory pressure (PEEP) levels for mechanically ventilated adult patients with acute lung injury and acute respiratory distress syndrome (March 2021) and High‐flow nasal cannulae for respiratory support in adult intensive care patients (March 2021).
Prophylactic anticoagulants for people hospitalised with COVID-19
COVID‐19 may predispose people to getting blood clots in the arteries, veins and lungs. Venous and arterial thromboembolic complications affect 16% of people hospitalised with COVID‐19 and 31% to 49% of people with COVID‐19 in intensive care units, with 90% of such cases being venous thromboembolism. A Cochrane Review, Prophylactic anticoagulants for people hospitalised with COVID‐19, has looked for evidence on the effects of using blood thinning drugs to prevent this in people hospitalised with COVID-19.
As yet, there are no published randomisedRandomization 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 trials and the authors conclude that there is insufficient evidence to determine the risks and benefits of prophylactic anticoagulants in this populationThe group of people being studied. Populations may be defined by any characteristics e.g. where they live, age group, certain diseases. More. However, they found 22 studies in progress which plan to evaluate 15,000 people, which will be considered for future updates of the review.
Care bundles for people with COVID-19 or related conditions in intensive care
Cochrane has published a scoping review on care bundles for improving outcomes in patients with COVID-19 or related conditions in intensive care (December 2020) to map the existing evidence. The review authors found 21 studies and also identified three ongoing studies. Seven included patients with COVID-19. Most care bundles involved practices related to breathing support or ventilator settings, or the positioning of a patient, and COVID‐19‐specific studies also focused on infection control and use of personal protective equipment (PPE). There now needs to be a systematic reviewIn 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 of this evidence.
Chloroquine or hydroxychloroquine for treatment of COVID‐19
A Cochrane Review on Chloroquine or hydroxychloroquine for prevention and treatment of COVID‐19 brings together the available evidence from randomised trials on the effectiveness and safetyRefers to serious adverse effects, such as those that threaten life, require or prolong hospitalization, result in permanent disability, or cause birth defects. More of hydroxychloroquine (HCQ) for treating people with COVID-19 and preventing COVID-19 disease in people exposed to the virus (SARS‐CoV‐2). All the studies currently included in the review investigated hydroxychloroquine and not chloroquine. The review authors are also interested in the evidence on the use of these drugs for preventing COVID-19 disease in people at risk of exposure to the virus (such as healthcare workers), but there are no trial results ready to report for this.
When used to treat people with COVID-19, there is high-certainty evidence that HCQ makes little or no difference to the risk of dying from the disease, compared with standard care or placeboAn 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. There is moderate-certaintyThe certainty (or quality) of evidence is the extent to which we can be confident that what the research tells us about a particular treatment effect is likely to be accurate. Concerns about factors such as bias can reduce the certainty of the evidence. Evidence may be of high certainty; moderate certainty; low certainty or very-low certainty. Cochrane has adopted the GRADE approach (Grading of Recommendations Assessment, Development and Evaluation) for assessing certainty (or quality) of evidence. Find out more here: https://training.cochrane.org/grade-approach More evidence that it probably does not reduce the chances of needing mechanical ventilation. The risks of adverse events are probably increased with HCQ. The effect of HCQ in preventing illness in people who have been exposed to the virus is very uncertain, but again it probably increases the risk of adverse events.
There is a Cochrane editorial on this review: Contested effects and chaotic policies: the 2020 story of (hydroxy) chloroquine for treating COVID‐19 (published March 2021) and also a Cochrane Clinical Answer: For adults with coronavirus disease 2019 (COVID-19), what are the benefits and harms of hydroxychloroquine?
Interleukin‐6 blocking agents for treating COVID‐19
Interleukin-6 is a protein involved in immune responses. Medicines that block interleukin-6 are used to treat other conditions, like rheumatoid arthritis, that involve an ‘over-reactive’ immune system. They have been used for treating severe COVID-19 and a new Cochrane Review Interleukin‐6 blocking agents for treating COVID‐19: a living systematic review (published March 2021) has been done to look for evidence of its effectiveness and safety.
The review includes 10 studies with 6896 people with COVID-19 (average age 56 to 65 years), comparing one of two interleukin-6 blocking medicines, tocilizumab and sarilumab, with placebo (a dummy treatment that looks the same as the medicine but lacks the active ingredient) or ‘standard care’.
There is high-certainty evidence that treatment with tocilizumab reduced the number of people who died, of any cause, after 28 days. It probably makes little or no difference to time to leaving hospital or clinical symptoms. It probably slightly reduces the number of serious unwanted effects such as life-threatening conditions or death. Its effect on the severity of COVID-19 is uncertain. There is uncertainty about the effects of sarilumab, although the review authors report that it probably does not cause more unwanted effects (of any type) than placebo.
The review authors found some ongoing trials of interleukin-blocking medicines used to treat COVID-19 that haven’t yet reported results. This is a living systematic reviewA Living Systematic Review is a systematic review which is continually updated, incorporating relevant new evidence as it becomes available. More and the results will be updated with new data as soon as possible.
Vitamin D supplementation for treating COVID-19
A Cochrane Review on Vitamin D supplementation for the treatment of COVID‐19: a living systematic review (May 2021) has found just three studies with 356 people with COVID-19 (including asymptomatic, mild, moderate and severe disease), comparing vitamin D supplementation with placebo or ‘standard care’. The authors conclude that “There is currently insufficient evidence to determine the benefits and harms of vitamin D supplementation as a treatment of COVID‐19”. They identified 21 ongoing studies and three completed studies without published results, so their findings are likely to change when the review is updated.
Preventing and treating persistent problems with sense of smell after COVID-19 infection
A Cochrane Review on Interventions for the prevention of persistent smell disorders (olfactory dysfunction) after COVID‐19 infection and another on Interventions for the treatment of persistent smell disorders after COVID‐19 infection were published in July 2020. They each include only one small studyAn 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 and highlight current uncertainty about how to prevent or treat ongoing problems with sense of smell after COVID-19. However, the review authors found that there are studies being done at the moment and will be able to assess these for inclusion in updates of this ‘living systematic review’, adding new research as it becomes available.
Here’s what they found:
The impact of the pandemic on other areas of health and wellbeing
Resilience and mental health of frontline healthcare professionals
Working on the ‘front line’ as a health or social care professional during a pandemic is stressful and can negatively impact workers’ mental health. A Cochrane Review on interventions to support the resilience and mental health of frontline health and social care professionals during and after a disease outbreak, epidemic or pandemic aimed to assess the effects of such interventions and explore things that make it easier or harder to implement them, through both qualitative and qualitative evidence.
InterventionA treatment, procedure or programme of health care that has the potential to change the course of events of a healthcare condition. Examples include a drug, surgery, exercise or counselling. More effects remain uncertain. They were explored in just one study. All 16 studies in the review had some limited evidence on things that might help interventions to be successfully delivered. This review highlights a need for robust evaluation of interventions and the review authors suggest that the current pandemic provides unique opportunities for doing so.
Interventions for heavy menstrual bleeding
Pandemics disrupt healthcare provision. With this in mind, a Cochrane overview of reviewsCochrane Overviews of reviews (Overviews) are intended to summarize multiple Cochrane Reviews addressing the effects of two or more potential interventions (for example a drug, surgery, or exercise) for a single condition or health problem. More (July 2020) has been done on interventions commonly available during pandemics for heavy menstrual bleeding. You can see summaries of the review here, including an infographic to help women make choices about treatment. There is also a podcast about this review and two Cochrane Clinical Answers.
Routine vaccinations during the pandemic
The World Health Organization (WHO) has emphasized the importance of keeping up with routine vaccinations during the pandemic, advice endorsed by Public Health England. A Cochrane Review on vaccines for measles, mumps, rubella and varicella in children (published April 2020) was discussed in this blog: “MMR vaccines: do they work and are they safe?“.
There are two Cochrane Clinical Answers related to this review.
Social isolation and loneliness in older people
With restrictions imposed during the pandemic increasing isolation for many, a Cochrane rapid review (May 2020) looked for evidence on video calls for reducing social isolation and loneliness in older people. We discuss the review in this blog: “Loneliness in older people: could video calls help?”
There is also a podcast and a Cochrane Clinical Answer.
Quitting smoking to improve respiratory health
Given the current threat from COVID-19, an acute respiratory infection, there has never been a better time to stop smoking, and the World Health Organization is urging people to do so. We have looked at evidence from a new Cochrane Special Collection, COVID-19: Effective options for quitting smoking during the pandemic, in this blog: “Smoking and coronavirus (COVID-19): time to quit.”
Coronavirus (COVID-19): Special Collections
The Special Collection on quitting smoking during the pandemic is one of seven Cochrane Special Collections on COVID-19. Developed with experts from our global Cochrane network, they are based on World Health Organization interim guidance, and continuously updated.
Coming up…
Like the reviews themselves, we update our blogs to reflect the latest evidence. There are new reviews coming up, as well as updates of existing reviews, so check back for additions to this blog.
We also welcome news of two new clinical trials which have been launched in the UK to investigate potential preventative treatments for the most clinically vulnerable (those with long-term underlying conditions and those in care homes) to prevent them catching COVID-19.
Keeping up to date
As well as coming back to this blog, you can find Cochrane resources and news on COVID-19 here and this will also be continually updated.
Join in the conversation on Twitter with @CochraneUK @SarahChapman30 or leave a comment on the blog. Please note, we will not publish comments that link to commercial sites or appear to endorse commercial products. We welcome diverse views and encourage discussion but ask that comments are respectful and reserve the right to not publish comments we consider offensive.
Sarah Chapman has nothing to disclose.
I found this blog incredibly useful to present what we have done in Cochrane and why. Thank you very much Sarah!
I liked very much those informations!