We all knew it was borrowed time, and looking at the percentage of asymptomatic infected people, evidence suggested it was wrong.
It's no different to stores going into daily deep-cleaning of surfaces back in March. Surface transmission hasn't been found to be common. We didn't know how to respond, so we did everything we thought could help.
If you selected travelers randomly (that's what I was getting at by saying every tenth), what percentage would have been found to have COVID-19?
If you are asking about the ground truth, the study does not include that. However, these people were selected because they were coming from countries with high incidences of coronavirus, like Iran and the United Kingdom, so it is likely that many people with coronavirus were not caught.
The study also mentions that findings are consistent with models that predicted symptom screening would not detect most cases, implying that they believe most cases were not detected through screening:
These findings are consistent with mathematical models examining the effectiveness of airport screening for COVID-19, which suggest that most infected travelers would be undetected by symptom-based screening at airports (4,5).
This temperature monitoring discussion is only regards to travelers. The link below is what the CDC published. The CDC still maintains that business guidelines are temperature screening to be used as a mitigation strategy.
Screening employees is an optional strategy that employers may use.
That was last updated in September. If this more recent study (published in mid November) makes them change their stance to actively discourage temperature screening, it may take some time to update all the pages.
Here it is for anyone interested. They still list having employees self-check at home as an optional strategy for risk mitigation and give guidelines for safe fever screening at an entrance, but do not mention it as a strategy for mitigation.
Thanks Zach, while I agree they give preference to self-screening, I don't see that they are saying onsite screening is not a mitigation. We're probably just interpreting the statements slightly differently.
Read just a little further down in that section of the FAQ and it goes into detail of how to temperature screen an individual. Sound like on-site screening is an option too. So many options to choose from!
They mention self-checks before coming in as an option and then give safety advice on how to do in-person screening. The implication I get is they recommend self-reporting, but if people choose to screen, they want it to be done safely.
This feels like too small of a study to rule out symptom and fever scanning as a whole. The study also focused on limiting the importation of COVID from international travelers from countries that was added to throughout the study. Even the thresholds for testing were not consistent:
The threshold for sending symptomatic travelers for public health assessment and deciding which among those would be sent for medical evaluation varied during the evaluation period, reflecting evolution of CDC’s definition for “person under investigation”§§ and operational considerations (e.g., testing capacity). Until March 20, travelers from Hubei Province were quarantined for 14 days upon arrival under federal or state authority.
The results of the study also highlights that all screening, not just fever, is ineffective for detection of international travelers (Title is a little misleading). Not trying to promote fever detection cameras at all, but IPVM might be a little irresponsible to dismiss all forms of screening for applications outside of the parameters of this study. The way I read the CDC's report is that this study is primarily focused on international travelers in a handful of airport from countries that were not consistent throughout the study.
What would be an appropriate sized study in your opinion, and why?
The sample size isn't the big issue here, it is the scope (restricted to airports). I think a better study would be 1,000,000 random temperature screenings would give a better metric.
We are not ruling it out, we are saying this study found it innefective.
It does not look like the definition of fever ever changed even if thresholds for other symptoms did:
Fair point, but even in the study 48 people measured a fever and only 15 of those that registered a fever received a test. Of those 15 people, 5 tested positive for COVID-19. So, 33% of those that were actually tested came back positive. Only 31% of those that had a fever, got tested. While the definition of a fever did not change, apparently the response to a fever did. Going even deeper only 35 of the 278 that met the criteria were ever tested. If you go by the positive tests of those tested, 26%, then out of the 278 that met the criteria...72 would be positive and not the 9 reported.
I think a better study would be 1,000,000 random temperature screenings would give a better metric.
I agree that would be a better study, but we have not seen anything similar.
Fair point, but even in the study 48 people measured a fever and only 15 of those that registered a fever received a test.
The step after raising an alert was a health examination, not a coronavirus test. So, the examiner may have remeasured their temperature with a more accurate device and found it to be normal, ruled them out for another reason, or there may not have been testing capacity. Assuming people were randomly not tested may be true, but the CDC suggests the decision was made by a medical examiner based on their prognosis of the subjects' symptoms.
Regardless, even if you triple the amount caught by fever screening, the number still looks small to me: 15/776,044 participants or 0.0019%. And symptom screening becomes 72/776,044 or 0.0093%. Do you think these numbers would have a different conclusion?
Even the study states that most travelers were not sent to local facility or tests for COVID-19. So they admit that the findings in the report are limited.
The findings in this report are subject to at least three limitations. First, not all symptomatic travelers were referred for public health assessment because many COVID-19 symptoms are nonspecific and available data (for travelers who were not referred) are insufficient to determine the proportion who might have had some symptoms. Second, most travelers referred for public health assessment were not sent to a local health care facility or tested for SARS-CoV-2. Both could have been sources of selection bias toward underestimation of the number of cases in screened travelers.
I feel that if the report states their findings are limited, you can't derive that screening is not effective. Expensive yes, but ineffective no. Out of all the people screened, 48 people had a fever. Even though not all were tested, 5 (10%) were positive. A 1 in 10 chance of a person found having a fever and also having COVID is a decent rate IMO. This is speculation, but maybe people who felt ill decided to wait on their flight so the number of fever detections is low...I know I hate flying when I don't feel good.
Testing/referral to a local health facility came after on-site health assessments. This could have led to underestimation, but the unreferred/untested people were probably not random
The third step included referral of ill travelers and those disclosing an exposure for additional public health assessment by an on-site medical officer;if indicated, travelers were sent to a local health care facility for medical evaluation.
The main point, that I believe the CDC is making, is not that you should ignore symptoms if they are present, but that they are an ineffective way of screening for coronavirus.
A 1 in 10 chance of a person found having a fever and also having COVID
Is how good fever is at diagnosing coronavirus. I am in no way suggesting people with fevers should come into contact with others. Fevers are a sign someone may be contagious with something and that they should stay home to avoid potentially spreading whatever it is.
5 (or 15)/776,044 is how effective fever screening is at finding people with coronavirus from a population believed to be high-risk. That is the number that we are highlight makes fever screening innefective.
Out of all the people screened, 48 people had a fever. Even though not all were tested, 5 (10%) were positive. A 1 in 10 chance of a person found having a fever and also having COVID is a decent rate IMO.
The core issue is the 1 out of every 15,000+ having a fever. Even if you said 'everyone who measures a fever has coronavirus', that's still 0.007%. And we know there's lots of ways to have a fever and not have coronavirus.
but maybe people who felt ill decided to wait on their flight so the number of fever detections is low...I know I hate flying when I don't feel good.
Seems fair, and for the same reason, people who have fevers are unlikely to go to Cracker Barrel, the bowling alley, etc.
Imagine a scenario where people with fevers would more likely want to go and try to hide it, what's the percentage than? 1 in 10,000? 1 in 5,000?
It's important for people to understand how rare this is. Knowing this, also helps to show people how easy it is therefore to rig a system and make people believe it works, since real fevers are so rare.
And then a Hawaiian couple gets arrested boarding a flight who knowingly are infected...interesting that they tested positive then were entered into a database of known individuals for "Do Not Fly" list, and it worked.
That percentage you cite is not the actual percentage of fevers, because they didn't measure core body temps. You've seen by now that many, if not most, forehead IR scanners are garbage and should not be on the market, yet that's what they relied on in this study. They perform only slightly better than the Bems tablets, which completely make up numbers. Look at the clinical trial supported by the FDA's CDRH, which used thermal imaging carefully. The forehead IR scanners should never have ended up as a "gold standard" to compare other technologies against.
They don't specify beyond "noncontact infrared thermometer" which probably means "using a spot pyrometer at the forehead" as opposed to trying to manually target the inner canthus.
We haven't found a conclusive answer to what is better: an accurate handheld up close or an accurate high res snapshot from farther away as studies have had mixed results and results vary greatly by the device tested.
That is true and we have reached out. However, handheld noncontact thermometers often use just a single pixel from close up, instead of many from far away, so there may be less variability in handheld performance than the kiosks and bullets we have tested. But it is still good to know.
Want to know how I know John H. wrote the voice narrative for the short video? Notice the excessive use of the word "indeed". Indeed, John enjoys preluding an affirmative statement with the word, "indeed".
Indeed, after doing a quick search, there does appear to be a strong correlation between beginning a sentence with "indeed" and John Honovich's authorship. It should be noted, however, that it is not 100% certain. Other staff writers use this construction from time to time, BrianRhodes and CharlesRollet using it the most. Whether this is a sign of input from John (unlikely if he isn't credited) or whether they are subconsciously picking up his speech patterns, I don't know.
Of course they only found 9 fevers in over 700K travellers, because the forehead IR scanners and nearly every product on the market fudges their numbers so strongly, the devices are basically useless. In a typical population a real device that doesn't push numbers to the average _should_ have had a false positive rate of at least a few percent (meaning, there _ought_ to have been at least a few thousands of false positives requiring a repeat scan, its a clear red flag that there weren't). Even the FDA-cleared noncontact (forehead) IR scanners do this extreme averaging to the normal body temperature, which I've documented (and shared with IPVM) on our website at feverinspect.com. If they'd used our system, they would have caught numerous real fevers. We did it right and we might be one of possibly only two or three companies who doesn't have to fudge numbers in order to not report absurd readings, but the damage to the market has already been done. I look forward to reading about the class action lawsuits against some of these sellers.
Fever scanning detection seems a bit high-level description for an unnamed, handheld , non-contact thermometer. No cameras involved. I assume the CDC still recommends the questionnaire? [a temperature check using a noncontact infrared thermometer (fever defined as temperature ≥100.4°F [38°C]),]
Having said that it is remarkable that almost none were identified. Does that mean that none of them in reality met the level, or is it an indictment of methods/implementation. Maybe they got thermometers from HIK or Dahua subsidiaries.
But if actual screening still catches some people, why dismiss it? Especially if the CDC is predicting yesterday that it will get worse:
The situation is likely to get worse, with Centers for Disease Control and Prevention Director Robert Redfield warning that the next three months are “going to be the most difficult time in the public health history of this nation.” Redfield said the U.S. death toll — currently at 272,000 — could reach 450,000 by February.
They, as we stated, called it ineffective. It can lead to a false sense of security and resources can be spent elsewhere, such as ventilation, physical barriers, PPE, etc which may have more impact. They also do not make any statement about individuals checking for symptoms at home (where you can use more accurate thermometers), simply about the efficacy of their screening for symptoms and fevers.
Zach, they called it ineffective in relation to public health which is not the same as a workplace or business environment. Businesses aren't run as a zero sum game, all of the things you mentioned including changes in ventilation, physical barriers and PPE are already being done, screening would be an added layer on top of that.
The reason this dodgy technology should be totally banned is the false sense of security the average end user gets. The assumption, by the end user, is that as the thermal camera has not said the target has a fever then all is OK
I never said use a thermal camera, I am not a proponent of using thermal cameras for screening at this time. I was referring to thermal/symptom screenings and do believe those can be tools to mitigate spread...not a catch all approach. Which is the exact same thing CDC is telling people to do at home. Don't know about everyone else, but I've never calibrated my at home thermometer or check for it's accuracy.
but I've never calibrated my at home thermometer or check for it's accuracy.
Oral and ear thermometers are considered more accurate than infrared ones, which makes sense because they are placed in your mouth or ear respectively as opposed to several inches or feet away. While calibration is important, if a device is not accurate, calibration cannot make up for it. And, not all at-home devices are calibratable, ie mercury thermometers. However, accurate devices can be miscalibrated which would make them inaccurate as well.
If you are curious, this is a compilation of different relevant papers I found. While there is disagreement on what methods are best, research supports oral and ear as superior to fever cameras.
After reading the CDC study, a more accurate title for the story would have been: In public health practice, CDC finds symptom-based screening programs are ineffective. The CDCs statement however is not specific to temperature devices, nor is there anything in the report discussing accuracy of those devices in detecting someone who is febrile, instead it basically states that any kind of symptom based screening of arriving passengers does not generate a good return on investment.
I will start by saying that from the beginning I did not feel that temperature screening alone is an effective way to manage Covid 19 and that fever detection devices are going to pick up less than 10% of the infected people. This study does seem to confirm that, regardless of any other conclusions made.
Unfortunately, this article and the video does not attempt to put any context to the statement, which was made as an implication for public health practice vs a business scenario, and as a secondary consideration, the group being studied was limited to those traveling internationally via air from specific countries.
Public health practice like business is concerned about the best use of limited resources, in the CDCs case by discontinuing the airport screening program, they could use better use those people in areas where they can contribute to reducing spread of the virus. In the case of businesses, since they should already be following the other guidelines, there is no benefit to not screen for symptoms. As even this study shows, there is an ever so slight benefit to a business conducting some level of screening as this represents an additional cost that would not be to the detriment of the things it should be doing.
Then there are the factors involved in international air travel that differ from someone visiting say the local Cracker Barrel or going to work. This includes the fact that the airlines were conducting their own pre-screenings, international air travel is quite a bit more involved than a visit to a local business, and the fact that the sample was limited to a changing list of departure countries rather than all arriving passengers.
The first two items above by themselves would mean that those actively showing symptoms would be less likely to get to the point they are screened on arrival anyway. The report itself points out the limitations, one key one being not everyone who was flagged got a Covid test or even saw a healthcare provider, so ultimately we don't know if any of those ended up with a Covid diagnoses later down the road. We also don't know how many people who were not flagged were asymptomatic at the time, so there is no way to validate claims of accuracy, just that the cost/detected infection was extremely high and that ultimately the money would be better spent elsewhere in the public health system.
Businesses have other considerations (legal risk being one of the big ones I can think of) that might justify the use of some kind of screening, whether it involves temperature screening or not is a different matter.
John, just because fever camera sellers are using legal risk as a tool to sell cameras doesn't mean the concern doesn't exist, and I have seen it mentioned on multiple back to work plans. I also mentioned it myself as far back as February.
BTW if you read everything I said (it's a lot I know) you'll realize I'm not talking about fever cameras but conducting any type of symptom based screening which is what the CDC study is about. In fact the CDC study neither proves or disproves the accuracy of temperature monitoring devices themselves (and didn't even involve fever cameras). The study also does not include any follow up showing the number of asymptomatic carriers that slipped through the screening making it harder to accurately determine effectiveness outside of cost/detected individual.
Outside of Canada, all of the health leaders quoted in your linked report specifically discussed fever cameras and not other types of screening which is the context I was talking about.
Related, I'm not selling fever cameras but if I did it would only be at customer request, and I would have to do a lot of vetting to ensure the ones I am selling aren't "rigged. I appreciate the effort IPVM has done in helping sort the good from the bad in this.
my issue was that the sales team that wanted to sell anything that said body temperature camera, and go with the cheapest route. i wasted lots of research time making sure we didn't jump on something that would upset the customers down the road because of it's unreliability and made sure we told them that it would just measure the outer body temperature and not the core
David, I think that is a prudent approach. I personally do not think EST cams are worth the price but if a customer wants to deploy one following FDA, CDC and ISO guidelines then I would be happy to help sell and install it.
The challenge is that most customers don't want to spend the money needed for a good deployment, may or may not be open to being educated in the matter, and at the end of the day could end up exposing themselves to a lawsuit because they deployed or used the device improperly.