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What is the efficacy of standard face masks compared to respirator masks in preventing COVID-type respiratory illnesses in primary care staff? – a lay summary

This is a lay summary of a report repared for the Oxford COVID-19 Evidence Service of the Oxford Centre for Evidence Based Medicine, Nuffield Department of Primary Care Health Sciences, University of Oxford by Trish Greenhalgh, Xin Hui Chan, Kamlesh Khunti, Quentin Durand-Moreau, Sebastian Straube, Declan Devane, Elaine Toomey and Anil Adisesh, and posted on 24th March 2020, updated 30th March 2020.

Standard surgical face masks are loose-fitting, while respirator masks (known in the USA as N95 and in the UK as a Filtering Face Piece or FFP mask) are designed to fit closely to the user’s face and be more efficient at filtering out tiny airborne particles and droplets. There are concerns over the risk posed by shortages of personal protective equipment (PPE) for health care staff, so this review wanted to see whether having to use standard surgical masks could pose a hazard to those who cannot access respirator masks.

Most real-world research comparing standard face masks with respirator masks has been in the context of influenza and other respiratory conditions, and based in hospitals – not in community settings. And no head-to-head studies comparing different kinds of masks have yet been published about use in COVID-19. So, there is a shortage of evidence. But what we can be reasonably certain of so far is:

  • COVID-19 is spread when droplets or tiny airborne particles coughed or sneezed by an infected person come into contact with a mucosal surface – usually the inside of somebody’s nose, mouth or the surface of their eye. The infected droplets or particles either travel through the air, or they can land on a surface and be picked up when somebody touches the surface, then their face. There is some evidence that particles landing on a surface can become airborne again when disturbed.
  • Neither type of mask prevents all infection. When caring for an infected person, the masks must be used in combination with other personal protective measures including aprons or gowns, goggles or face shields, and gloves. Users should be properly trained in how to put on and remove protective clothing in ways that minimize the chance of contamination, and to apply general infection control measures such as effective handwashing, tying back hair and removing jewellery.
  • Both types of mask are disposable and should be used only once then thrown away very carefully.
  • The standard surgical mask stops splashes and droplets coming into contact with the wearer’s nose and mouth. It fits fairly loosely to the user’s face, and should be changed if it becomes moist or damaged.
  • Guidelines currently recommend respirator masks, with their close fit and finer weave, for greater protection against exposure to airborne particles – very small particles that can carry infectious agents, remaining in the air for long periods of time and being carried over long distances by air currents. Airborne particles can be released in coughs and sneezes, and during certain medical procedures.
  • However, studies comparing standard surgical with respirator masks, when used with other recommended protective clothing by healthcare staff caring for patients with a variety of influenza-like viral illnesses, found no real differences between the ability of the two types of mask to prevent spread of the diseases.

Mandy Payne, 31 March 2020

Disclaimer: the article has not been peer-reviewed; it should not replace individual clinical judgement and the sources cited in the original report should be checked. The views expressed in this commentary represent an interpretation by HealthWatch and do not necessarily represent those of Oxford CEBM, the NHS, the NIHR, or the Department of Health and Social Care. The views are not a substitute for professional medical advice.

What is the evidence for social distancing during global pandemics? – a lay summary

This is a lay summary of a report repared for the Oxford COVID-19 Evidence Service of the Oxford Centre for Evidence Based Medicine, Nuffield Department of Primary Care Health Sciences, University of Oxford by Kamal R Mahtani, Carl Heneghan, and Jeffrey K Aronson, and posted on 20th March 2020.

In response to the COVID-19 pandemic, the UK government has mandated “social distancing” measures, such as restricting when people can leave their homes, and closing schools and public spaces, to reduce transmission of the virus.

Are the measures likely to be enough? Or too much? Real-time decision making needs to be based on the best possible evidence. But the body of knowledge around COVID-19, although growing all the time, is still limited. In the meantime policy decisions have to be made, and where there are information gaps we need to take into account experience from other similar scenarios, such as past influenza pandemics. The best available evidence from previous pandemics supports social distancing measures as being effective at reducing and delaying the spread of infection, although the benefits may come at a heavy social cost.

  • Self-isolation and other measures that keep infected people from making physical contact with others has been found to reduce the rate of infection spread and may also delay the pandemic’s peak – buying valuable time for health services to get ready.
  • Home quarantine for people who have been exposed to the disease but who do not show symptoms, can also help slow the spread of infection. But there could be risk to others in the same household, especially if the quarantine lasts for a long time.
  • Contact tracing, particularly when combined with other social distancing measures, may delay the peak of a pandemic. However it is resource-intensive, so may need to be limited to cases where it will bring the greatest benefit.
  • School closures have helped reduce spread during influenza pandemics, although there is no agreement over when and for how long to close – there is some evidence that infections may bounce back again after school reopens. Prolonged school closures can also be counter-productive if infected children simply carry the disease to other social groups; they also handicap workforces and can result in loss of income for parents. There is a danger that some children might be poorly cared for, or themselves be left in charge of younger siblings.
  • Changes in the workplace, such as remote working, staggered shifts, and extended holidays, have also been shown to help slow spread and delay peak infection. But the gains must be balanced against loss of income from work closures, and interruptions to supply chains for essential and important goods.
  • Avoiding crowds and mass gatherings, and travel restrictions – the evidence is less strong for these but they may be beneficial if combined with other interventions.

Evidence specific to the current COVID-19 pandemic is limited but some trends are emerging. No one measure is likely to make much difference on its own – interventions need to be combined. Modelling studies suggest that self-isolation of people suspected of having COVID-19, coupled with home quarantine for those living in the same household, and social distancing of elderly people and others at most risk of severe disease might halve the number of deaths and reduce peak healthcare demand by two-thirds and deaths by a half. The greatest benefits seem to come from step-by-step introduction of social distancing measures, beginning in the areas with the highest prevalence. Getting the timing right is crucial.

Mandy Payne, 1 April 2020

Disclaimer: the article has not been peer-reviewed; it should not replace individual clinical judgement and the sources cited in the original report should be checked. The views expressed in this commentary represent an interpretation by HealthWatch and do not necessarily represent those of Oxford CEBM, the NHS, the NIHR, or the Department of Health and Social Care. The views are not a substitute for professional medical advice.

What is the effectiveness and safety of antiviral or antibody treatments for coronavirus? – a lay summary

This is a lay summary of a report repared for the Oxford COVID-19 Evidence Service of the Oxford Centre for Evidence Based Medicine, Nuffield Department of Primary Care Health Sciences, University of Oxford by Patricia Rios, Amruta Radhakrishnan, Jesmin Antony, Sonia M Thomas, Mathew Muller, Sharon E Straus, Andrea C Tricco and posted on 26th March 2020.

Are there yet any safe and effective drugs we can use to fight infection with COVID-19? This review looked at the available evidence around medicines that have so far been used against coronaviruses, with the hope of identifying safe and effective treatments for the current outbreak.

  • The team reviewed studies from around the world that have reported experience of treating patients infected with different coronaviruses. These included SARS-CoV-1, the coronavirus that caused the 2002-2003 outbreak of severe acute respiratory syndrome (SARs); MER-CoV which causes Middle East Respiratory Syndrome (MERS), a rare disease first identified in 2012; and SARS-CoV-2 – the coronavirus responsible for the current outbreak of the disease we now call COVID-19.
  • The review looked into the safety and effectiveness of treating coronaviruses with antivirals – drugs that specifically target viruses. In coronavirus, the most researched antiviral is ribavirin, a drug normally used against the hepatitis C virus. Other studies used the influenza drug oseltamivir, or combinations of two other antiviral drugs.
  • The review also looked for studies reporting experience of treating COVID-19 patients with antibiotics and steroids; and also interferons and monoclonal antibodies, which are used in cancer to boost the body’s natural defences.
  • It found the current evidence for safety and effectiveness of antiviral therapies for coronavirus infections is inconclusive, and did not point to any particular treatments that could be recommended for use against COVID-19. There was a lack of well-designed trials of coronavirus treatments overall which means the quality of evidence may not be reliable enough on which to base treatment recommendations.
  • Ribavirin, the most studied antiviral, is of questionable effectiveness in coronavirus and has been associated with worrying side effects, such as anaemia, digestive problems, and altered liver function.
  • Four randomized controlled trials testing treatments for COVID-19 have been begun in China. These are examining various combinations of antiviral medications and, in one case, antivirals used alongside traditional Chinese medicine. These trials are so far in very early stages.

Mandy Payne, 30 March 2020

Disclaimer: the article has not been peer-reviewed; it should not replace individual clinical judgement and the sources cited in the original report should be checked. The views expressed in this commentary represent an interpretation by HealthWatch and do not necessarily represent those of Oxford CEBM, the NHS, the NIHR, or the Department of Health and Social Care. The views are not a substitute for professional medical advice.

How accurate is the wrist style blood pressure cuff folks tend to buy from the chemist/online? – a lay summary

This is a lay summary of a report repared for the Oxford COVID-19 Evidence Service of the Oxford Centre for Evidence Based Medicine, Nuffield Department of Primary Care Health Sciences, University of Oxford by Uy Hoang and posted on 23rd March 2020.

  • There is some early evidence that high blood pressure may be linked to poorer outcomes in those hospitalized with the most severe effects of COVID-19 infection.
  • Wrist blood pressure monitors are cheap, easy to use and readily available online and from pharmacies. But are they accurate?
  • The National Institute for Clinical Excellence (NICE) says that wrist blood pressure monitors are likely to provide reasonably accurate home blood pressure assessment in most people.
  • Oxford CEBM reviewed the best available evidence and found only one clinical trial specific to wrist devices. It found the devices were able to correctly categorize users’ blood pressure as being either high, or within the normal range, in about 4 out of 5 cases. Devices with a position sensor were slightly more accurate – reading correctly in 5 out of 6 cases.
  • International guidelines generally recommend that for the most accurate readings, blood pressure should be measured at the upper arm, especially in patients with obesity and high blood pressure. There is as yet no specific evidence available on the use of home blood pressure monitoring in patients with COVID-19 or other acute respiratory illness.

Mandy Payne, 27 March 2020

Disclaimer: the article has not been peer-reviewed; it should not replace individual clinical judgement and the sources cited in the original report should be checked. The views expressed in this commentary represent an interpretation by HealthWatch and do not necessarily represent those of Oxford CEBM, the NHS, the NIHR, or the Department of Health and Social Care. The views are not a substitute for professional medical advice.

Accuracy of strip-like forehead thermometers – a lay summary

This is a lay summary of a report repared for the Oxford COVID-19 Evidence Service of the Oxford Centre for Evidence Based Medicine, Nuffield Department of Primary Care Health Sciences, University of Oxford by Jon Brassey and Carl Heneghan, and posted on 23rd March 2020.

  • Plastic strip thermometers that are laid on the forehead are popular with parents as they are cheap and easy to use, especially with sleeping or uncooperative children. But their readings are nowhere near as accurate as the traditional mercury glass thermometer.
  • In around 4 in 10 cases, parents using a forehead strip on a child with fever may be misled into thinking their temperature is normal. 
  • If you only have a forehead strip thermometer, allow for the actual temperature measurement to be out by at least +/-1.5°C and take repeated measurements over time.

Mandy Payne, 27 March 2020

Disclaimer: the article has not been peer-reviewed; it should not replace individual clinical judgement and the sources cited in the original report should be checked. The views expressed in this commentary represent an interpretation by HealthWatch and do not necessarily represent those of Oxford CEBM, the NHS, the NIHR, or the Department of Health and Social Care. The views are not a substitute for professional medical advice.