This week’s big controversy concerns the CDC’s deciding to cut recommended days for isolation for people infected with Covid. CDC director Walensky was all over the news explaining that this “was the moment” for a cut, given the whopping number of new Covid cases (over 400,000 on Dec. 28, exceeding the previous record which was in the 300,000’s).
“In the context of the fact that we were going to have so many more cases — many of those would be asymptomatic or mildly symptomatic — people would feel well enough to be at work, they would not necessarily tolerate being home, and that they may not comply with being home, this was the moment that we needed to make that decision,” Walensky told CNN.
The CDC had already explained last week that “health care workers’ isolation period could be cut to five days, or even fewer, in the event of severe staffing shortages at U.S. hospitals”.
Then, on Monday, the CDC announced that individuals who test positive for Covid-19 and are asymptomatic need to isolate for only five days, not 10 days, citing increasing evidence that people are most infectious in the initial days after developing symptoms.
What’s really causing alarm among many health experts is that the new policy has no requirement for a negative test result, with a rapid test, before ending isolation. Even if you test positive on day 5, the CDC says, you can go about your business. So long as you’re asymptomatic or mildly symptomatic or your “symptoms are resolving” and you wear a mask. I don’t suppose the new looser guidance would result in any pressure being put on a pilot or other worker to get back to work even with some mild brain fog or coughing that seemed to be resolving. Continue reading →
Last week, giving a long postponed talk for the NY/NY Metro Area Philosophers of Science Group (MAPS), I mentioned how my book Statistical Inference as Severe Testing: How to Get Beyond the Statistics Wars (2018, CUP) invites the reader to see themselves on a special interest cruise as we revisit old and new controversies in the philosophy of statistics–noting that I had no idea in writing the book that cruise ships would themselves become controversial in just a few years. The first thing I wrote during early pandemic days last March was this post on the Diamond Princess. The statistics gleaned from the ship remain important resources which haven’t been far off in many ways. I reblog it here.Continue reading →
Have you ever wondered if people read Master’s (or even Ph.D) theses a decade out? Whether or not you have, I think you will be intrigued to learn the story of why an obscure Master’s thesis from 2012, translated from Chinese in 2020, is now an integral key for unravelling the puzzle of the global controversy about the mechanism and origins of Covid-19. The Master’s thesis by a doctor, Li Xu , “The Analysis of 6 Patients with Severe Pneumonia Caused by Unknown Viruses”, describes 6 patients he helped to treat after they entered a hospital in 2012, one after the other, suffering from an atypical pneumonia from cleaning up after bats in an abandoned copper mine in China. Given the keen interest in finding the origin of the 2002–2003 severe acute respiratory syndrome (SARS) outbreak, Li wrote: “This makes the research of the bats in the mine where the six miners worked and later suffered from severe pneumonia caused by unknown virus a significant research topic”. He and the other doctors treating the mine cleaners hypothesized that their diseases were caused by a SARS-like coronavirus from having been in close proximity to the bats in the mine. Continue reading →
The “mask wars” are a major source of disagreement and politicizing science during the current pandemic, but my interest here is not of clashes between pro-and anti-mask culture warriors, but the clashing recommendations among science policy officials and scientists wearing their policy hats. A recent Washington Post editorial by Joseph Allen, (director of the Healthy Buildings program at the Harvard T.H. Chan School of Public Health), declares “Everyone should be wearing N95 masks now”. In his view: Continue reading →
Although I have researched on clinical trial design for many years, prior to the COVID-19 epidemic I had had nothing to do with vaccines. The only object of these amateur musings is to amuse amateurs by raising some issues I have pondered and found interesting. Continue reading →
Stephen Senn Consultant Statistician Edinburgh, Scotland
Alpha and Omega (or maybe just Beta)
Well actually, not from A to Z but from AZ. That is to say, the trial I shall consider is the placebo- controlled trial of the Oxford University vaccine for COVID-19 currently being run by AstraZeneca (AZ) under protocol AZD1222 – D8110C00001 and which I considered in a previous blog, Heard Immunity. A summary of the design features is given in Table 1. The purpose of this blog is to look a little deeper at features of the trial and the way I am going to do so is with the help of geometric representations of the sample space, that is to say the possible results the trial could produce. However, the reader is warned that I am only an amateur in all this. The true professionals are the statisticians at AZ who, together with their life science colleagues in AZ and Oxford, designed the trial. Continue reading →
The idea of local control is fundamental to the design and analysis of experiments and contributes greatly to a design’s efficiency. In clinical trials such control is often accompanied by randomisation and the way that the randomisation is carried out has a close relationship to how the analysis should proceed. For example, if a parallel group trial is carried out in different centres, but randomisation is ‘blocked’ by centre then, logically, centre should be in the model (Senn, S. J. & Lewis, R. J., 2019). On the other hand if all the patients in a given centre are allocated the same treatment at random, as in a so-called cluster randomised trial, then the fundamental unit of inference becomes the centre and patients are regarded as repeated measures on it. In other words, the way in which the allocation has been carried out effects the degree of matching that has been achieved and this, in turn, is related to the analysis that should be employed. A previous blog of mine, To Infinity and Beyond, discusses the point. Continue reading →
As much as doctors and hospitals are raising alarms about a shortage of ventilators for Covid-19 patients, some doctors have begun to call for entirely reassessing the standard paradigm for their use–according to a cluster of articles to appear in the last week. “What’s driving this reassessment is a baffling observation about Covid-19: Many patients have blood oxygen levels so low they should be dead. But they’re not gasping for air, their hearts aren’t racing, and their brains show no signs of blinking off from lack of oxygen.” Within that group of patients, some doctors wonder if the standard use of mechanical ventilators does more harm than good. The issue is controversial; I’ll just report what I find in the articles over the past week. Please share ongoing updates in the comments. Continue reading →
Q. Was it a mistake to quarantine the passengers aboard the Diamond Princess in Japan?
A. The original statement, which is not unreasonable, was that the best thing to do with these people was to keep them safely quarantined in an infection-control manner on the ship. As it turned out, that was very ineffective in preventing spread on the ship. So the quarantine process failed. I mean, I’d like to sugarcoat it and try to be diplomatic about it, but it failed. I mean, there were people getting infected on that ship. So something went awry in the process of quarantining on that ship. I don’t know what it was, but a lot of people got infected on that ship. (Dr. A Fauci, Feb 17, 2020)
This is part of an interview of Dr. Anthony Fauci, the coronavirus point person we’ve been seeing so much of lately. Fauci has been the director of the National Institute of Allergy and Infectious Diseases since all the way back to 1984! You might find his surprise surprising. Even before getting our recent cram course on coronavirus transmission, tales of cruises being hit with viral outbreaks are familiar enough. The horror stories from passengers on the floating petri dish were well known by this Feb 17 interview. Even if everything had gone as planned, the quarantine was really only for the (approximately 3700) passengers because the 1000 or so crew members still had to run the ship, as well as cook and deliver food to the passenger’s cabins. Moreover, the ventilation systems on cruise ships can’t filter out particles smaller than 5000 or 1000 nanometers.Continue reading →