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posted by martyb on Sunday July 05 2020, @02:44PM   Printer-friendly
from the Panopticon,⠀M.D. dept.

How Infrared Images Could Be Part of Your Daily Life:

A fever is one indicator that someone may be exhibiting coronavirus symptoms, and the Centers for Disease Control and Prevention recommends temperature screenings in a variety of environments, including schools and businesses.

[...] When the pandemic took hold, I started seeing more and more companies like Amazon using this technology to help identify sick people in their warehouses. Thermal imaging cameras are beginning to appear in Subway restaurants. Carnival Cruise Lines, whose ships became hot spots for the virus’s spread, said all passengers and crew would be screened when it began sailing again.

The rapid adoption of infrared technology had me wondering how helpful it could be. Several systems are being rolled out, including camera-based ones and others that make people walk through thresholds like metal detectors. Could they actually help contain the spread of the virus while we wait for a vaccine?

A Harris Poll conducted in late March, just after the majority of the shelter measures went into place across the United States, found that 84 percent of respondents favored mandatory health screenings to enter public places.

[...] The growing use of the technology has raised privacy and other concerns.

Civil liberties experts have warned about data being collected on employees and used without their permission. Democratic and Republican lawmakers have proposed bills to help protect people’s information and privacy as data like temperature readings is collected, but the legislation has so far stalled in Congress.

“The road to hell is paved in good intentions, and the mass rollout of cameras should be seen for what it is: the mass rollout and further normalization of cameras,” said Ed Geraghty, a technologist at Privacy International, a British nongovernmental organization focused on privacy rights.

“We already see police repurposing streetlight cameras, put in place to monitor traffic and environmental data, in order to form criminal cases against those accused of vandalism — it would be naïve to believe the same will not be the case with these cameras,” he added.

All of this being said, could this technology work if used correctly? Yes. Is it better than nothing? It depends who you ask. But while we wait for a vaccine to be made, many see the benefits.

But will throwing infrared cameras up all over society make us safer from the virus? How might a grade school student react to seeing a classmate set off an infrared-based alarm walking into school? Will the time it takes to screen everyone trying to get into a building create problems for schools or offices? These are important questions that we will face in a post-quarantine world.


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  • (Score: 0, Interesting) by Anonymous Coward on Sunday July 05 2020, @07:46PM (2 children)

    by Anonymous Coward on Sunday July 05 2020, @07:46PM (#1016602)

    The papers you linked to were both older studies than either paper I linked to and used smaller sample sizes (9 and 23 cases versus 90 and 100). The conclusions drawn by the papers you linked to were that viral load peaks a few days after symptoms develop. These are older studies that have since been contradicted by newer studies. All other things equal, there's a smaller margin of error when a larger sample size is used to estimate the mean of a distribution. Therefore, absent evidence to the contrary, the results from studies with larger sample sizes should be preferred. These studies suggest that viral load peaks around the time a patient first develops symptoms. Moreover, I'll link you to another article (https://publichealth.jmir.org/2020/2/e19464/ [jmir.org]) that discusses the frequency of asymptomatic transmission and cites a number of other studies about this.

    Papers like the two you cited initially suggested that presymptomatic and asymptomatic transmission did not make a large contribution to the spread of the virus. Larger and more recent studies contradict this, which indicates that a large amount of the spread of the virus is due to people who don't have symptoms when they're spreading the virus. If they don't have symptoms, temperature checks won't detect that they're infected. It doesn't seem that the peak of infectiousness occurs four days after the onset of symptoms like earlier studies suggested. Regardless of whether the peak of infectiousness is at the start of symptoms or peaks in the couple of days prior to the onset of symptoms (as the first paper I linked to suggests), a large amount of transmission is driven by people who wouldn't be detected by temperature screenings.

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  • (Score: 0) by Anonymous Coward on Sunday July 05 2020, @10:29PM (1 child)

    by Anonymous Coward on Sunday July 05 2020, @10:29PM (#1016677)

    The conclusions drawn by the papers you linked to were that viral load peaks a few days after symptoms develop.

    No, now you're outright lying. Among the conclusions for my first linked paper...

    A high viral load on presentation of COVID-19 was recorded in our cohort, even for patients who were hospitalised shortly after symptom onset. Using nasal swab and throat swab, Zou and colleagues have also reported a high viral load shortly after symptom onset.

    The high viral load on pre-sentation suggests that SARS-CoV-2 can be transmitted easily, even when symptoms are relatively mild.

    Since viral load had already peaked around the time of hospital admission

    And the second...

    In the present study, peak concentrations were reached before day 5

    Critically, the majority of patients in the present study seemed to be beyond their shedding peak in samples from the upper respiratory tract when they were first tested, whereas the shedding of infectious virus in sputum continued throughout the first week of symptoms.

    seroconversion early in week 2 coincides with a slow but steady decline of viral load in sputum.

    It doesn't seem that the peak of infectiousness occurs four days after the onset of symptoms like earlier studies suggested.

    Did you miss where I bolded "within 5 days of symptom onset" from the second paper you linked?

    Papers like the two you cited initially suggested that presymptomatic and asymptomatic transmission did not make a large contribution to the spread of the virus.

    You should have no problem quoting those sections then (spoiler: papers do not mention this) but it's really beside the point, your disputed claim was that the virus was more transmissible before symptom onset and you have presented zero evidence to support that. For your enjoyment, here's a discussion paper on asymptomatic transmission. [sciencedirect.com]

    • (Score: 1, Insightful) by Anonymous Coward on Monday July 06 2020, @12:40AM

      by Anonymous Coward on Monday July 06 2020, @12:40AM (#1016748)

      To avoid this post from being needlessly confusing, I've quoted your text without additional formatting, but quotes from peer-reviewed journal papers are in bold.

      The conclusions drawn by the papers you linked to were that viral load peaks a few days after symptoms develop.

      No, now you're outright lying. Among the conclusions for my first linked paper...

      Viral load is plotted in blue on figure 2 in your first paper [thelancet.com]. As I noted previously, there are large errors due to the small sample size. However, the peak in the mean viral load in saliva from the patients that were sampled actually occurred around day 4.

      Here's what the first paper said about exactly that figure:

      The viral load in posterior oropharyngeal saliva samples was highest during the first week of symptom onset then gradually declined (slope –0·15, 95% CI –0·19 to –0·11; R²=0·71; figure 2).

      You also omitted text from the portion you quoted:

      Using nasal swab and throat swab, Zou and colleagues have also reported a high viral load shortly after symptom onset. However, in that study, only cycle threshold values (not exact viral loads) were reported...

      That caveat, which you did not include, is useful in interpreting the conclusions of the paper those authors referenced.

      As for the second paper [nature.com] you quoted:

      Pharyngeal virus shedding was very high during the first week of symptoms, with a peak at 7.11 × 108 RNA copies per throat swab on day 4.

      In fact, you quoted this exact text in your original comment. How, exactly, is it lying to reference the exact text you quoted in your original comment? It would be appropriate for you to reconsider what you said and clarify it.

      Let's contrast these results with what's in the papers I cited.

      From the first paper [nature.com]:

      In conclusion, we have estimated that viral shedding of patients with laboratory-confirmed COVID-19 peaked on or before symptom onset, and a substantial proportion of transmission probably occurred before first symptoms in the index case.

      And from the conclusions of the second paper [jamanetwork.com]:

      In summary, the findings of this study suggest that most transmission of COVID-19 occurred at the very early stage of the disease or even before the onset of symptoms, and the secondary clinical attack rate among contacts decreased over time as symptoms developed and progressed.

      And then part of your final paragraph:

      You should have no problem quoting those sections then (spoiler: papers do not mention this) but it's really beside the point, your disputed claim was that the virus was more transmissible before symptom onset and you have presented zero evidence to support that.

      A few months ago, public health authorities downplayed the risk of asymptomatic and presymptomatic transmission, guidance that has now changed to reflect the belief that asymptomatic and presymptomatic transmission is much more prevalent. The early guidance was likely informed by early papers such as the two you cited, along with experience with other coronavirus such as SARS and MERS. In regard to whether presymptomatic individuals are more infectious let's take a look at the paper you linked most recently [sciencedirect.com], specifically this quote:

      In addition, a recently published study by He et al.[35] used clinical and epidemiological data to estimate that patients infected with SARS-CoV-2 may be infectious from 2.3 days prior to symptom onset, with a peak at 0.7 days prior.

      So, the review paper you linked actually cites another paper [nature.com] staying that the peak of infectiousness occurs prior to the onset of symptoms. Incidentally, that paper happens to be the first one I cited. So your review paper accepts it as evidence that infectiousness peaks prior to the onset of symptoms, yet you say no evidence was presented. In fact, there is evidence, and as I noted previously, the sample size from this paper is larger than from either of the two papers you referenced, meaning the margin of error should be lower.

      I believe you should read the linked papers from this thread (there are five of them) again, then clarify your comments.