7 ms·

I think we could just stick with positivity rates and case numbers to figure that out, like we have been doing. Once the vaccines start working their magic, we’

I think we could just stick with positivity rates and case numbers to figure that out, like we have been doing. Once the vaccines start working their magic, we’ll see it in those metrics. That way we don’t have to try and guess how infectious someone can still be after they have had the vaccine

SamBam 6y ago
Exactly. Fixating on the vaccination percentage is simply using a number that's two steps removed from what's actually important. It's like trying to decide if it's too rainy to go out by figuring out how many people are watering their yards right now, when you could just look out and see if it's raining.
- evandijk70 6y ago
  Still we use weather forecast when we decide to make plans tomorrow. The best way to predict wether we can make plans (summer holidays, festivals, etc.) should involve some combination of the vaccination percentage and epidemological models.
  - SamBam 6y ago
    Seeing what the case positivity is this week is the best way to decide whether the vaccine has been effective enough to go out this week. Looking at the vaccine numbers for this week is a worse proxy. How does it help? Sure, you could use the projected vaccinations for next March to decide how likely it is that you'll be able to go and watch a broadway show in March, but, like the weather forecast, you'll need to know what the actual positivity is in March to make the final decisions.
midasuni 6y ago
No evidence that the vaccine stops spread, or even slows it down. It improves outcomes, so hospitals won’t be overloaded. Israel is over 40% on first dose and should have interesting reault sun the next month or two.
- ThrustVectoring 6y ago
  No evidence that it doesn't, either. It's simply hard to get this evidence and irrelevant for getting vaccines approved, so nobody has bothered. And it'd be really odd if it didn't help wrt infection rate.
  - disgruntledphd2 6y ago
    Yeah, it would be great if the vaccine does prevent spread, but we should act like it doesn't until we know more. As someone mentioned upthread, Israel will be an early indicator here.
  - midasuni 6y ago
    Irellevent for getting it approved, not irellevent for herd immunity purposes
- deleted 6y ago
  [deleted]
- voiper1 6y ago
  Well it's only 40% if you count only the over age 16 population. (Israel is not vaccinating under age 16 until more information.) If you look at the entire population, it's only about 28% got 1st dose and 12% got second dose, many within the last week. But with a population of about 9.3 million (size and population comparable to New Jersey) and they just ramped up to about 1million vaccinations a week, we could be at "full" vaccination March 26th - 85% of eligible population, 2nd dose, and 1 week for it to take affect. Source: Israel's ministry of health https://datadashboard.health.gov.il/COVID-19/general https://datadashboard.health.gov.il/COVID-19/general and wikipedia's population information https://en.wikipedia.org/wiki/Demographics_of_Israel#Age_structure https://en.wikipedia.org/wiki/Demographics_of_Israel#Age_str...
- graeme 6y ago
  This is the new “we have no evidence masks help” or “no evidence of asymptomatic spread”. Name a vaccine that doesn’t reduce onward transmission even as it cures disease. It’s overwhelmingly likely that the vaccine will slow transmission and foolish to throw our priors in the garbage bin. What we don’t know yet is how much onward transmission will be reduced.
SpicyLemonZest 6y ago
The concern is that we might end up in the same awkward spot we hit in the summer, where non-conscientious people decide everything's okay and nobody wants to relax the official restrictions for fear of emboldening them. (If you were strictly following California's published rules, for example, you wouldn't have had any private gathering for any reason between March and October.)
justnotworthit 6y ago
At what number can we stop wearing masks, stop social distancing, start dining in, etc.? That's the number I care about. Because until somebody influential picks that number, we'll just keep masking and social distancing until the end of time.
nanis 6y ago
> I think we could just stick with positivity rates and case numbers to figure that out, like we have been doing Sticking only with positivity rates is misleading even if one ignores all the costs of lockdowns. As the WHO pointed out on 13 January 2021[1]: > WHO reminds IVD users that disease prevalence alters the predictive value of test results; as disease prevalence decreases, the risk of false positive increases (2). This means that the probability that a person who has a positive result (SARS-CoV-2 detected) is truly infected with SARS-CoV-2 decreases as prevalence decreases, irrespective of the claimed specificity. You may find this comment[2] by me and the link to the calculator to understand the impact of varying prevalence keeping false positive and false negative rates constant. Note also, > Most PCR assays are indicated as an aid for diagnosis, therefore, health care providers must consider any result in combination with timing of sampling, specimen type, assay specifics, clinical observations, patient history, confirmed status of any contacts, and epidemiological information. In plain English, that says that with no illness and no contact with people suffering from Covid19 etc, a positive test does not necessarily mean that the person testing positive is infected. This is all basic Stats but it has been conspicuously ignored for almost year now. > The cycle threshold (Ct) needed to detect virus is inversely proportional to the patient’s viral load. So, before the test, pick a Ct, and stick with it instead of keeping on going until you get a positive result. At higher counts, the test might be detecting left over material from a long gone infection. > Where test results do not correspond with the clinical presentation, a new specimen should be taken and retested using the same or different NAT technology. So, if you are sick and get a negative, test again to make sure you can rule out SARS-Cov2. But, equivalently, if you are not sick and test positive, also make sure that this is not a false positive. The latter is what has been globally ignored with one positive test on healthy people is regarded as proof of infection and illness. It is what is being ignored when people are not allowed to travel or work due to a positive test result. Basically, a positive test result, even without symptoms, and even with a subsequent negative, puts a scarlet letter on you which cannot be erased. The flowchart in Figure 1 in this document[3] might also be useful. Note the first box is labeled "Patient meets the clinical criteria for COVID-19". That's where these diagnostic tests are applicable as proof of infection. The fact that the test is useful for confirmation of infection conditional on presenting symptoms doesn't mean it is useful for screening an entire population or deciding on how much GDP to destroy because of the simple facts that in that scenario a large portion of positive test results will be false positives and these tests have high false negative rates. [1]: https://www.who.int/news/item/20-01-2021-who-information-notice-for-ivd-users-2020-05 https://www.who.int/news/item/20-01-2021-who-information-not... [2]: https://news.ycombinator.com/item?id=25894449 https://news.ycombinator.com/item?id=25894449 [3]: https://apps.who.int/iris/bitstream/handle/10665/334254/WHO-2019-nCoV-laboratory-2020.6-eng.pdf?sequence=1&isAllowed=y https://apps.who.int/iris/bitstream/handle/10665/334254/WHO-...

SamBam 6y ago

Exactly. Fixating on the vaccination percentage is simply using a number that's two steps removed from what's actually important. It's like trying to decide if it's too rainy to go out by figuring out how many people are watering their yards right now, when you could just look out and see if it's raining.

evandijk70 6y ago
Still we use weather forecast when we decide to make plans tomorrow. The best way to predict wether we can make plans (summer holidays, festivals, etc.) should involve some combination of the vaccination percentage and epidemological models.
- SamBam 6y ago
  Seeing what the case positivity is this week is the best way to decide whether the vaccine has been effective enough to go out this week. Looking at the vaccine numbers for this week is a worse proxy. How does it help? Sure, you could use the projected vaccinations for next March to decide how likely it is that you'll be able to go and watch a broadway show in March, but, like the weather forecast, you'll need to know what the actual positivity is in March to make the final decisions.

midasuni 6y ago

No evidence that the vaccine stops spread, or even slows it down. It improves outcomes, so hospitals won’t be overloaded. Israel is over 40% on first dose and should have interesting reault sun the next month or two.

ThrustVectoring 6y ago
No evidence that it doesn't, either. It's simply hard to get this evidence and irrelevant for getting vaccines approved, so nobody has bothered. And it'd be really odd if it didn't help wrt infection rate.
- disgruntledphd2 6y ago
  Yeah, it would be great if the vaccine does prevent spread, but we should act like it doesn't until we know more. As someone mentioned upthread, Israel will be an early indicator here.
- midasuni 6y ago
  Irellevent for getting it approved, not irellevent for herd immunity purposes
deleted 6y ago
[deleted]
voiper1 6y ago
Well it's only 40% if you count only the over age 16 population. (Israel is not vaccinating under age 16 until more information.) If you look at the entire population, it's only about 28% got 1st dose and 12% got second dose, many within the last week. But with a population of about 9.3 million (size and population comparable to New Jersey) and they just ramped up to about 1million vaccinations a week, we could be at "full" vaccination March 26th - 85% of eligible population, 2nd dose, and 1 week for it to take affect. Source: Israel's ministry of health https://datadashboard.health.gov.il/COVID-19/general https://datadashboard.health.gov.il/COVID-19/general and wikipedia's population information https://en.wikipedia.org/wiki/Demographics_of_Israel#Age_structure https://en.wikipedia.org/wiki/Demographics_of_Israel#Age_str...
graeme 6y ago
This is the new “we have no evidence masks help” or “no evidence of asymptomatic spread”. Name a vaccine that doesn’t reduce onward transmission even as it cures disease. It’s overwhelmingly likely that the vaccine will slow transmission and foolish to throw our priors in the garbage bin. What we don’t know yet is how much onward transmission will be reduced.

SpicyLemonZest 6y ago

The concern is that we might end up in the same awkward spot we hit in the summer, where non-conscientious people decide everything's okay and nobody wants to relax the official restrictions for fear of emboldening them. (If you were strictly following California's published rules, for example, you wouldn't have had any private gathering for any reason between March and October.)

justnotworthit 6y ago

At what number can we stop wearing masks, stop social distancing, start dining in, etc.? That's the number I care about. Because until somebody influential picks that number, we'll just keep masking and social distancing until the end of time.

nanis 6y ago

> I think we could just stick with positivity rates and case numbers to figure that out, like we have been doing Sticking only with positivity rates is misleading even if one ignores all the costs of lockdowns. As the WHO pointed out on 13 January 2021[1]: > WHO reminds IVD users that disease prevalence alters the predictive value of test results; as disease prevalence decreases, the risk of false positive increases (2). This means that the probability that a person who has a positive result (SARS-CoV-2 detected) is truly infected with SARS-CoV-2 decreases as prevalence decreases, irrespective of the claimed specificity. You may find this comment[2] by me and the link to the calculator to understand the impact of varying prevalence keeping false positive and false negative rates constant. Note also, > Most PCR assays are indicated as an aid for diagnosis, therefore, health care providers must consider any result in combination with timing of sampling, specimen type, assay specifics, clinical observations, patient history, confirmed status of any contacts, and epidemiological information. In plain English, that says that with no illness and no contact with people suffering from Covid19 etc, a positive test does not necessarily mean that the person testing positive is infected. This is all basic Stats but it has been conspicuously ignored for almost year now. > The cycle threshold (Ct) needed to detect virus is inversely proportional to the patient’s viral load. So, before the test, pick a Ct, and stick with it instead of keeping on going until you get a positive result. At higher counts, the test might be detecting left over material from a long gone infection. > Where test results do not correspond with the clinical presentation, a new specimen should be taken and retested using the same or different NAT technology. So, if you are sick and get a negative, test again to make sure you can rule out SARS-Cov2. But, equivalently, if you are not sick and test positive, also make sure that this is not a false positive. The latter is what has been globally ignored with one positive test on healthy people is regarded as proof of infection and illness. It is what is being ignored when people are not allowed to travel or work due to a positive test result. Basically, a positive test result, even without symptoms, and even with a subsequent negative, puts a scarlet letter on you which cannot be erased. The flowchart in Figure 1 in this document[3] might also be useful. Note the first box is labeled "Patient meets the clinical criteria for COVID-19". That's where these diagnostic tests are applicable as proof of infection. The fact that the test is useful for confirmation of infection conditional on presenting symptoms doesn't mean it is useful for screening an entire population or deciding on how much GDP to destroy because of the simple facts that in that scenario a large portion of positive test results will be false positives and these tests have high false negative rates. [1]: https://www.who.int/news/item/20-01-2021-who-information-notice-for-ivd-users-2020-05 https://www.who.int/news/item/20-01-2021-who-information-not... [2]: https://news.ycombinator.com/item?id=25894449 https://news.ycombinator.com/item?id=25894449 [3]: https://apps.who.int/iris/bitstream/handle/10665/334254/WHO-2019-nCoV-laboratory-2020.6-eng.pdf?sequence=1&isAllowed=y https://apps.who.int/iris/bitstream/handle/10665/334254/WHO-...