5 ms·

This is important, because lots of internet commentators are just going with the most alarming possible statements: 28 day incubation periods, people can get in

by knzhou 7y ago

This is important, because lots of internet commentators are just going with the most alarming possible statements: 28 day incubation periods, people can get infected twice, airborne transmission, asymptomatic transmission. These assertions are all based on outlier cases, sometimes even single cases, observed during the fog of war. Even if these accounts are correct, they aren't the typical case, which is what actually matters for policy and prevention. The typical case has been well-known for months: most people get fevers, the incubation period is usually a few days, and most transmission is from symptomatic cases and via droplets. The WHO has collected stats from tens of thousands of cases and they've been straightforwardly pointing in this direction the entire time. There definitely is a serious problem, but misinformation helps nobody, even if its spreaders are well-meaning. For example, I've seen a lot of people take the inflated statements ("28 day incubation period!!") to mean that stopping the spread is completely impossible, while we have seen by example that it isn't.

mantap 7y ago
I don't share your optimism. The virus has been able to successfully evade e.g. testing people's temperatures in airports. It doesn't really matter if there are asymtomatic carriers or not, it doesn't matter whether people eventually get a high fever. What matters is whether people with non-specific/mild symptoms (a dry cough) can pass on the infection. And the answer is emphatically yes.
- tylerhou 7y ago
  Bypassing airport temperature tests is an incredibly low bar because it rarely catches other diseases. Anecdotally, I've travelled multiple times with people who have had fevers and entered countries with routine temperature screening and haven't been stopped. Human body temperature is also so variable that a small fever is masked by the margin of error.
  - fspeech 7y ago
    You don't need to catch everyone. You just need to bring R0 to below 1. If R0 is a little over 2 in the first place you just need to catch a little over 50% of the infected with all your actions (in addition to temperature checking) to eventually control the epidemic. The better you do the sooner you get it under control.
    - rpearl 7y ago
      Not quite... You'd need to catch a bit over half of all cases _before they passed on the virus to anyone else at all_ to bring R0 below 1 in this fashion.
  - mantap 7y ago
    It's a low bar for many of the common and less deadly illnesses that we are used to. But relative to the mortality rate, it's more notable. People with SARS tended to get too sick to even go to the airport.
  - blhack 7y ago
    I've been somewhat shocked at seeing these forehead thermometers being used for screening. Forehead thermometers are not accurate. https://www.ncbi.nlm.nih.gov/pubmed/24127699 https://www.ncbi.nlm.nih.gov/pubmed/24127699 I challenge HN's readers to devise ways to defeat a forehead thermometer. IF we had a hackathon around this idea, how long until somebody devises a method of communication via forehead thermometer reading manipulation?
    - duckymcduckface 7y ago
      Smear some alcohol on your forehead before the check, the phase change as it evaporates will drastically decrease the local temperature where it's applied.
- potiuper 7y ago
  If a person has a fever, then he or she should not be at a public airport.
  - craftinator 7y ago
    Yes, I always cancel thousands of dollars worth of travel plans when I start coming down with something. I also always check my temperature right before entering an airport, so I can be sure to cancel my plans.
  - kalleboo 7y ago
    As long as airlines (and hotels, resorts, etc) don't let you reschedule for free or cancel for a full refund if you are sick people will keep flying sick. The same as as long as people don't get unlimited paid sick days and protection from being fired, they will keep going to work sick. These things need to be legislated if we want to reduce deaths and lost productivity from infections diseases (including the yearly flu)
    - hkai 7y ago
      Most airlines seem to allow rescheduling free of charge at this time? In Asia at least
rolph 7y ago
perhaps its just coincidence but could the "28 day incubation period" somehow resonate with the movie "28 days later" ? it seems like a way to take advantage of priming. https://en.wikipedia.org/wiki/Priming_(psychology) https://en.wikipedia.org/wiki/Priming_(psychology)
- bcrosby95 7y ago
  The specific number isn't widespread. People mention anywhere from 24 up to 30.
fspeech 7y ago
Analysis shows there might be two subtypes from the very early days: https://academic.oup.com/nsr/advance-article/doi/10.1093/nsr/nwaa036/5775463 https://academic.oup.com/nsr/advance-article/doi/10.1093/nsr... If the theory is correct, the L type is more aggressive and may be causing explosive outbreaks as in Wuhan, while the S type is less aggressive but harder to block from transmission. Interestingly, the S type is the ancestor. It would be interesting to see what is more prevalent in the outbreaks of South Korea, Italy and Iran.
- cbsks 7y ago
  Thank you for providing a primary source! I'm sick and tired of getting regurgitated information from the media (pun intended).
- rolph 7y ago
  yes its about time we start looking at the very real phenomenon of co-circulation of strains and co-infection. The model of one virus in circulation is simple for providing an explanation of how things work at a basic level but the real picture is somewhat more interactive.
koheripbal 7y ago
> The WHO has collected stats from tens of thousands of cases... This part is inaccurate. The WHO's best quality data set is South Korea, which is only a few thousand cases (the vast majority of which are still in the early stages of the illness). The data quality in places like Iran, China, and even the USA are TERRIBLE and should not be used to draw any conclusions. Additionally, the R0 is clearly different in different climates, so places like Singapore, Thailand, Vietnam, Malaysia, should not be used to infer infectivity in colder climates like Korea, Taiwan, Japan, Europe, and America. A great source for facts is the TWIV podcast - twiv.tv. They are experts in Virology and infectious disease control. > most people get fevers This is a bit misleading when the WHO says 3.4% of people die, and 5-10% require intensive case and mechanical ventilation. According to the CDC, the flu kills 0.05% of the 32 million people infected in the US annually. A 100X increase is devastating for healthcare systems. The systemic problems occur when masses of older people require more ICU beds and ventilators than are available, which then drives the mortality even higher. We should be tremendously thankful that children do not seem to be impacted. If it weren't so, the level of panic and economic damage would be significantly higher. Schools would already be closed and a HUGE portion of the workforce would be unable to work. > ...stopping the spread is completely impossible, while we have seen by example that it isn't. Given the global spread and the lack of testing in most non-first-world countries, most experts agree that the disease will not be contained and will become endemic. Think about North Korea, Mongolia, or Nepal - the fact that they are not reporting cases, should not be interpreted as evidence that no cases exist. The recommended WHO strategy is to SLOW the spread of the virus with a balanced strategy of containment and mitigation. The goal is to buy us enough time to develop and deploy a vaccine.

by knzhou 7y ago

mantap 7y ago

I don't share your optimism. The virus has been able to successfully evade e.g. testing people's temperatures in airports. It doesn't really matter if there are asymtomatic carriers or not, it doesn't matter whether people eventually get a high fever. What matters is whether people with non-specific/mild symptoms (a dry cough) can pass on the infection. And the answer is emphatically yes.

tylerhou 7y ago
Bypassing airport temperature tests is an incredibly low bar because it rarely catches other diseases. Anecdotally, I've travelled multiple times with people who have had fevers and entered countries with routine temperature screening and haven't been stopped. Human body temperature is also so variable that a small fever is masked by the margin of error.
- fspeech 7y ago
  You don't need to catch everyone. You just need to bring R0 to below 1. If R0 is a little over 2 in the first place you just need to catch a little over 50% of the infected with all your actions (in addition to temperature checking) to eventually control the epidemic. The better you do the sooner you get it under control.
  - rpearl 7y ago
    Not quite... You'd need to catch a bit over half of all cases _before they passed on the virus to anyone else at all_ to bring R0 below 1 in this fashion.
- mantap 7y ago
  It's a low bar for many of the common and less deadly illnesses that we are used to. But relative to the mortality rate, it's more notable. People with SARS tended to get too sick to even go to the airport.
- blhack 7y ago
  I've been somewhat shocked at seeing these forehead thermometers being used for screening. Forehead thermometers are not accurate. https://www.ncbi.nlm.nih.gov/pubmed/24127699 https://www.ncbi.nlm.nih.gov/pubmed/24127699 I challenge HN's readers to devise ways to defeat a forehead thermometer. IF we had a hackathon around this idea, how long until somebody devises a method of communication via forehead thermometer reading manipulation?
  - duckymcduckface 7y ago
    Smear some alcohol on your forehead before the check, the phase change as it evaporates will drastically decrease the local temperature where it's applied.
potiuper 7y ago
If a person has a fever, then he or she should not be at a public airport.
- craftinator 7y ago
  Yes, I always cancel thousands of dollars worth of travel plans when I start coming down with something. I also always check my temperature right before entering an airport, so I can be sure to cancel my plans.
- kalleboo 7y ago
  As long as airlines (and hotels, resorts, etc) don't let you reschedule for free or cancel for a full refund if you are sick people will keep flying sick. The same as as long as people don't get unlimited paid sick days and protection from being fired, they will keep going to work sick. These things need to be legislated if we want to reduce deaths and lost productivity from infections diseases (including the yearly flu)
  - hkai 7y ago
    Most airlines seem to allow rescheduling free of charge at this time? In Asia at least

rolph 7y ago

perhaps its just coincidence but could the "28 day incubation period" somehow resonate with the movie "28 days later" ? it seems like a way to take advantage of priming. https://en.wikipedia.org/wiki/Priming_(psychology) https://en.wikipedia.org/wiki/Priming_(psychology)

bcrosby95 7y ago
The specific number isn't widespread. People mention anywhere from 24 up to 30.

fspeech 7y ago

Analysis shows there might be two subtypes from the very early days: https://academic.oup.com/nsr/advance-article/doi/10.1093/nsr/nwaa036/5775463 https://academic.oup.com/nsr/advance-article/doi/10.1093/nsr... If the theory is correct, the L type is more aggressive and may be causing explosive outbreaks as in Wuhan, while the S type is less aggressive but harder to block from transmission. Interestingly, the S type is the ancestor. It would be interesting to see what is more prevalent in the outbreaks of South Korea, Italy and Iran.

cbsks 7y ago
Thank you for providing a primary source! I'm sick and tired of getting regurgitated information from the media (pun intended).
rolph 7y ago
yes its about time we start looking at the very real phenomenon of co-circulation of strains and co-infection. The model of one virus in circulation is simple for providing an explanation of how things work at a basic level but the real picture is somewhat more interactive.

koheripbal 7y ago

> The WHO has collected stats from tens of thousands of cases... This part is inaccurate. The WHO's best quality data set is South Korea, which is only a few thousand cases (the vast majority of which are still in the early stages of the illness). The data quality in places like Iran, China, and even the USA are TERRIBLE and should not be used to draw any conclusions. Additionally, the R0 is clearly different in different climates, so places like Singapore, Thailand, Vietnam, Malaysia, should not be used to infer infectivity in colder climates like Korea, Taiwan, Japan, Europe, and America. A great source for facts is the TWIV podcast - twiv.tv. They are experts in Virology and infectious disease control. > most people get fevers This is a bit misleading when the WHO says 3.4% of people die, and 5-10% require intensive case and mechanical ventilation. According to the CDC, the flu kills 0.05% of the 32 million people infected in the US annually. A 100X increase is devastating for healthcare systems. The systemic problems occur when masses of older people require more ICU beds and ventilators than are available, which then drives the mortality even higher. We should be tremendously thankful that children do not seem to be impacted. If it weren't so, the level of panic and economic damage would be significantly higher. Schools would already be closed and a HUGE portion of the workforce would be unable to work. > ...stopping the spread is completely impossible, while we have seen by example that it isn't. Given the global spread and the lack of testing in most non-first-world countries, most experts agree that the disease will not be contained and will become endemic. Think about North Korea, Mongolia, or Nepal - the fact that they are not reporting cases, should not be interpreted as evidence that no cases exist. The recommended WHO strategy is to SLOW the spread of the virus with a balanced strategy of containment and mitigation. The goal is to buy us enough time to develop and deploy a vaccine.