Tag: The Guardian

Covid, false positives and conditional probabilities…

Mary Pat Campbell

Link: https://www.theguardian.com/theobserver/commentisfree/2021/apr/25/covid-false-positives-and-conditional-probabilities

Excerpt:

In courtrooms, mixing up the probability of “A given B’” with “B given A” is known as the “prosecutor’s fallacy”. In 1999, a court convicted Sally Clark of the murder of her two sons, in part because a medical expert claimed the chance of two accidental cot deaths was one in 73m. Even if this number was right – which it isn’t – it did not reflect the chance she was innocent. A double murder was also very rare: the relative likelihood of the two explanations was key and with new evidence and better statistical reasoning, an appeal court quashed the conviction.

There was controversy after a recent Observer headline referred to Bayes’s theorem as “obscure”. His ideas may be little known by the public, but they are growing among scientists. Many complex analyses done during the pandemic have been “Bayesian”, including modelling lockdown effects, the ONS infection survey, and Pfizer-BioNTech’s vaccine trial. The term “credible interval”, rather than “confidence interval”, is the giveaway.

Last week, Cass Business School announced the renaming of its institution after Bayes and his theorem. The obscure tomb in nearby Bunhill Fields is worth a visit.

Author(s): David Spiegelhalter, Anthony Masters

Publication Date: 25 April 2021

Publication Site: The Guardian

The obscure maths theorem that governs the reliability of Covid testing

Mary Pat Campbell

Link: https://www.theguardian.com/world/2021/apr/18/obscure-maths-bayes-theorem-reliability-covid-lateral-flow-tests-probability

Excerpt:

This is important to know when thinking about “lateral flow tests” (LFTs), the rapid Covid tests that the government has made available to everyone in England, free, up to twice a week. The idea is that in time they could be used to give people permission to go into crowded social spaces – pubs, theatres – and be more confident that they do not have, and so will not spread, the disease. They’ve been used in secondary schools for some time now.

There are concerns over LFTs. One is whether they’ll miss a large number of cases, because they’re less sensitive than the slower but more precise polymerase chain reaction (PCR) test. Those concerns are understandable, although defenders of the test say that PCR testing is too sensitive, able to detect viral material in people who had the disease weeks ago, while LFTs should, in theory, only detect people who are infectious.

But another concern is that they will tell people that they do have the disease when in fact they don’t – that they will return false positives.

Author(s): Tom Chivers

Publication Date: 18 April 2021

Publication Site: The Guardian

Tui plane in ‘serious incident’ after every ‘Miss’ on board was assigned child’s weight

Mary Pat Campbell

Link: https://www.theguardian.com/world/2021/apr/09/tui-plane-serious-incident-every-miss-on-board-child-weight-birmingham-majorca

Excerpt:

A software mistake caused a Tui flight to take off heavier than expected as female passengers using the title “Miss” were classified as children, an investigation has found.

The departure from Birmingham airport to Majorca with 187 passengers on board was described as a “serious incident” by the Air Accidents Investigation Branch (AAIB).

An update to the airline’s reservation system while its planes were grounded due to the coronavirus pandemic led to 38 passengers on the flight being allocated a child’s “standard weight” of 35kg as opposed to the adult figure of 69kg.

Author(s): PA Media

Publication Date: 8 April 2021

Publication Site: The Guardian

How elimination versus suppression became Covid’s cold war

Mary Pat Campbell

Link: https://www.theguardian.com/commentisfree/2021/mar/03/covid-19-elimination-versus-suppression?mc_cid=919aa668d9&mc_eid=983bcf5922

Excerpt:

The rest of the world is pursuing a mitigation and suppression strategy, according to which we will have to live with Covid-19 and therefore we must learn to manage it – aiming for herd immunity by the most painless route possible. The poster child for this approach is Sweden’s chief epidemiologist, Anders Tegnell, who told me last week that elimination was a pipe dream for most of the world because even if a country were able to achieve it once, it would be impossible to prevent reintroductions without maintaining a costly and potentially restrictive surveillance apparatus. If the strategy failed, the country would have to revert to suppression anyway, but the population would have paid a much higher price. He too is in it for the long haul, he says; “sustainability” is his watchword. This is how he justifies the gradual tightening of restrictions in his country, from a very relaxed start.

And so the world is cleaved in two, with each bloc operating according to a different set of assumptions, in a kind of public health rerun of the cold war. One bloc assumes that Covid-19 can be eliminated, the other that it can’t. The latter thinks the former is chasing an impossible utopia. The former thinks the utopia could be achieved if only everyone pulled together.

Author(s): Laura Spinney

Publication Date: 3 March 2021

Publication Site: The Guardian

Green pass: how are Covid vaccine passports working for Israel?

Mary Pat Campbell

Link: https://www.theguardian.com/world/2021/feb/28/green-pass-how-are-vaccine-passports-working-in-israel?mc_cid=0edceb332a&mc_eid=983bcf5922

Excerpt:

In Israel, there is concern that the unvaccinated population, whatever their reasons, will be left behind or shunned. Small protests warning that green passes create a new hierarchy in society have been held.

Fresh ethical questions were raised last week when the Knesset, the country’s parliament, agreed to give local authorities personal details of unvaccinated residents to help them carry out targeted inoculation campaigns. Tamar Zandberg, a lawmaker, said it was a “slippery slope” for personal privacy.

Author(s): Oliver Holmes, Quique Kierszenbaum

Publication Date: 28 February 2021

Publication Site: The Guardian

‘Encouraging’ signs for Covid vaccine as over-80s deaths fall in England

Mary Pat Campbell

Link: https://www.theguardian.com/society/2021/feb/16/encouraging-signs-covid-vaccine-over-80s-deaths-fall-england

Graphic:

Excerpt:

Deaths from coronavirus have fallen by 62% among over-80s since 24 January, the point at which a third of that age group had some level of immunity against coronavirus, having received their first vaccine dose at least two weeks earlier, data analysis by the Guardian showed.

This drop was larger than among groups with a lower level of vaccination. Among people aged between 20 and 64 the drop in deaths was 47%, while the drop among those aged 65 to 79 was 51%.

Author(s): Anna Leach, Ashley Kirk, and Pamela Duncan

Publication Date: 16 February 2021

Publication Site: The Guardian

Up to 90 volunteers in UK to take part in pioneering Covid infection trial

Mary Pat Campbell

Link: https://www.theguardian.com/world/2021/feb/17/uk-to-begin-worlds-first-covid-human-challenge-study-within-weeks

Graphic:

Excerpt:

The world’s first coronavirus human challenge study will begin in the UK in a matter of weeks, following approval from the country’s clinical trials ethics body, the business department said.

Approval has been given for an initial trial that will involve up to 90 carefully screened, healthy, adult volunteers aged between 18 and 30. They will be exposed to the coronavirus in a safe, controlled environment. It is hoped further trials will follow.

“These are quite unique studies, able to accelerate not only understanding of diseases caused by infection, but also to accelerate the discovery of new treatments and of vaccines,” said Peter Openshaw, a professor of experimental medicine at Imperial College London.

Author(s): Nicola Davis

Publication Date: 17 February 2021

Publication Site: The Guardian

Fury at ‘do not resuscitate’ notices given to Covid patients with learning disabilities

Mary Pat Campbell

Link: https://www.theguardian.com/world/2021/feb/13/new-do-not-resuscitate-orders-imposed-on-covid-19-patients-with-learning-difficulties

Excerpt:

People with learning disabilities have been given do not resuscitate orders during the second wave of the pandemic, in spite of widespread condemnation of the practice last year and an urgent investigation by the care watchdog.

Mencap said it had received reports in January from people with learning disabilities that they had been told they would not be resuscitated if they were taken ill with Covid-19.

The Care Quality Commission said in December that inappropriate Do Not Attempt Cardiopulmonary Resuscitation (DNACPR) notices had caused potentially avoidable deaths last year.

DNACPRs are usually made for people who are too frail to benefit from CPR, but Mencap said some seem to have been issued for people simply because they had a learning disability. The CQC is due to publish a report on the practice within weeks.

Author(s): James Tapper

Publication Date: 13 February 2021

Publication Site: The Guardian

‘Do not resuscitate’ orders caused potentially avoidable deaths, regulator finds

Mary Pat Campbell

Link: https://www.theguardian.com/society/2020/dec/03/do-not-resuscitate-orders-caused-potentially-avoidable-deaths-regulator-finds

Excerpt:

Do-not-resuscitate orders were wrongly allocated to some care home residents during the Covid-19 pandemic, causing potentially avoidable deaths, the first phase of a review by England’s Care Quality Commission has found.

The regulator warned that some of the “inappropriate” do not attempt cardiopulmonary resuscitation (DNACPR) notices applied in the spring may still be in place and called on all care providers to check with the person concerned that they consent.

The review was prompted by concerns about the blanket application of the orders in care homes in the early part of the pandemic, amid then prevalent fears that NHS hospitals would be overwhelmed.

Author(s): Robert Booth

Publication Date: 2 December 2020

Publication Site: The Guardian