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Publications

Use of “normal” risk to improve understanding of dangers of covid-19 – BMJ

Accumulating data on deaths from covid-19 show an association with age that closely matches the “normal” risk we all face. Explaining risk in this way could help people understand and manage their response, says David Spiegelhalter

As covid-19 turns from a societal threat into a matter of risk management, it is vital that the associated risks are understood and clearly communicated.1 But these risks vary hugely between people, and so finding appropriate analogues is a challenge. Although covid-19 is a complex multisystem disease that can cause prolonged illness, here I focus solely on the risks of dying from covid-19 and explore the use of “normal” risk—the risk of death from all causes each year—as an aid to transparent communication.

  • General population: the risk of catching and then dying from covid-19 during 16 weeks of the pandemic was equivalent to experiencing around 5 weeks extra “normal” risk for those over 55, decreasing steadily with age, to just 2 extra days for schoolchildren
  • Over 55 who are infected with covid-19: additional risk of dying is slightly more than the “normal” risk of death from all other causes over one year, and less for under 55s.

https://www.bmj.com/content/370/bmj.m3259

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Preventing a covid-19 pandemic – BMJ

A randomized placebo-controlled trial in children showed that flu shots increased fivefold the risk of acute respiratory infections caused by a group of noninfluenza viruses, including coronaviruses. (Cowling et al, Clin Infect Dis 2012;54:1778) From Table 3, vaccine recipients had 20 noninfluenza virus-positive ARIs and 19 virus-negative ARIs; non-recipients had 3 noninfluenza virus-positive ARIs and 14 virus-negative ARIs. These figures yield an odds ratio of 4.91 (CI 1.04 to8.14).

Such an observation may seem counterintuitive, but it is possible that influenza vaccines alter our immune systems non-specifically to increase susceptibility to other infections; this has been observed with DTP and other vaccines. (Benn et al, Trends in Immunology, May 2013) There are other immune mechanisms that might also explain the observation.

https://www.bmj.com/content/368/bmj.m810/rr-0

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Opinion

Evidence-based medicine and COVID-19: what to believe and when to change – BMJ

The COVID-19 pandemic has led to a surge of information being presented to clinicians regarding this novel and deadly disease. There is a clear urgency to collate, review, appraise and act on this information if we are to do the best for clinicians and patients. However, the speed of the pandemic is a threat to traditional models of knowledge translation and practice change. In this concepts paper, we argue that clinicians need to be agile in their thinking and practice in order to find the right time to change. Adoption of new methods should be based on clinical judgement, the weight of evidence and the balance of probabilities that any new technique, test or treatment might work. The pandemic requires all of us to reach a new level of evidence-based medicine characterised by scepticism, thoughtfulness, responsiveness and clinically agility in practice.

https://emj.bmj.com/content/early/2020/07/09/emermed-2020-210098

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Publications

Interpreting a covid-19 test result – BMJ

No test gives a 100% accurate result; tests need to be evaluated to determine their sensitivity and specificity, ideally by comparison with a “gold standard.” The lack of such a clear-cut “gold-standard” for covid-19 testing makes evaluation of test accuracy challenging.

A systematic review of the accuracy of covid-19 tests reported false negative rates of between 2% and 29% (equating to sensitivity of 71-98%), based on negative RT-PCR tests which were positive on repeat testing. The use of repeat RT-PCR testing as gold standard is likely to underestimate the true rate of false negatives, as not all patients in the included studies received repeat testing and those with clinically diagnosed covid-19 were not considered as actually having covid-19.

Further evidence and independent validation of covid-19 tests are needed. As current studies show marked variation and are likely to overestimate sensitivity, we will use the lower end of current estimates from systematic reviews, with the approximate numbers of 70% for sensitivity and 95% for specificity for illustrative purposes.

https://www.bmj.com/content/369/bmj.m1808

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Publications

Covid-19: Doctors sound alarm over hospital transmissions – BMJ

Doctors have told The BMJ they are deeply concerned at the number of patients becoming infected with covid-19 in NHS hospitals in England and have called for more stringent infection control measures to combat its spread.

https://www.bmj.com/content/369/bmj.m2013

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Publications

“Staggering number” of extra deaths in community is not explained by covid-19 – BMJ

Only a third of the excess deaths seen in the community in England and Wales can be explained by covid-19, new data have shown.

Of those 30 000, only 10 000 have had covid-19 specified on the death certificate. While Spiegelhalter acknowledged that some of these “excess deaths” might be the result of underdiagnosis, “the huge number of unexplained extra deaths in homes and care homes is extraordinary. When we look back . . . this rise in non-covid extra deaths outside the hospital is something I hope will be given really severe attention.”

https://www.bmj.com/content/369/bmj.m1931

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Children are not COVID-19 super spreaders: time to go back to school – BMJ

At the current time, children do not appear to be super spreaders. Sero-surveillance data will not be available to confirm or refute these findings prior to the urgent policy decisions that need to be taken in the next few weeks such as how and when to re-open schools. Policies for non-pharmacological interventions involving children are going to have to be made on a risk–benefit basis with current evidence available.

https://adc.bmj.com/content/early/2020/05/05/archdischild-2020-319474

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Publications

A cluster randomised trial of cloth masks compared with medical masks in healthcare workers – BMJ (2015)

Penetration of cloth masks by particles was almost 97% and medical masks 44%.

This study is the first RCT of cloth masks, and the results caution against the use of cloth masks. This is an important finding to inform occupational health and safety. Moisture retention, reuse of cloth masks and poor filtration may result in increased risk of infection. Further research is needed to inform the widespread use of cloth masks globally. However, as a precautionary measure, cloth masks should not be recommended for HCWs, particularly in high-risk situations, and guidelines need to be updated.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4420971/

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Rapid response to: Face masks for the public during the covid-19 crisis – BMJ

In conclusion, as opposed to Greenhalgh et al., we believe that the context of the current covid-19 pandemic is very different from that of the “parachutes for jumping out of aeroplanes”,[7] in which the dynamics of harm and prevention are easy to define and even to quantify without the need of research studies. It is necessary to quantify the complex interactions that may well be operating between positive and negative effects of wearing surgical masks at population level. It is not time to act without evidence.

https://www.bmj.com/content/369/bmj.m1435/rr-40

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Publications

Vets would not manage Covid-19 this way – BMJ

There needs to be a more effective and sustainable strategy to manage Covid-19 than the current economically ruinous policy, argue vets Dick Sibley and Joe Brownlie.

https://veterinaryrecord.bmj.com/content/186/14/462.full

Categories
Opinion Publications

Excess deaths: government commissions review – BMJ

[Nicola Oliver ] tells us that 15,969 people died of flu (in England) last year, although only 320 died in hospital, and 15,649 were apparently left to die without due medical attention at home. What she fails to note is that the 15,969 deaths were not recorded deaths but a projection derived from the Flumomo algorithm [2] for ‘flu attributable deaths’ based on all cause mortality [3], so it does not really get us anywhere (except that it is just kind of thing I am complaining about!)

https://www.bmj.com/content/361/bmj.k2795/rapid-responses