4 ms·

Be careful interpreting this. Delta and now Omicron are more contagious than the original virus precisely because they have higher peak viral loads and shed mo

Be careful interpreting this. Delta and now Omicron are more contagious than the original virus precisely because they have higher peak viral loads and shed more virus from infected patients. Hence, the virus in wastewater per infected individual has been changing along with the number of infected individuals.

ripper1138 5y ago
Good point. Also keep in mind this is just one location. Would be really cool to see this measured by most cities.
- jvmiert 5y ago
  We do this in The Netherlands: https://coronadashboard.government.nl/landelijk/rioolwater https://coronadashboard.government.nl/landelijk/rioolwater
  - systemBuilder 5y ago
    Wow that is SICK! I think if I had to read viral particles in wastewater for many different diseases at a sewage treatment plant I would go crazy and move to the countryside!
    - yread 5y ago
      There is no "countryside" in the Netherlands
      - OneTimePetes 5y ago
        You can move water-sides though, buy a houseboat and camp out on the lakes..
twofornone 5y ago
Has that been proven or are you just speculating? I don't think increased viral load/shedding is the only mechanism by which a virus becomes more contagious.
- mlyle 5y ago
  Delta has been documented to result in higher viral loads and this is thought to be a factor behind the increased transmissibility. I don't think anyone knows about the kinetics of Omicron yet. I think the increasing prevalence of Omicron may have a lot more to do with its ability to escape immunity from past infection and increased probability of vaccine breakthrough than any inherent higher transmissibility to those who are immunologically naive.
  - anonuser123456 5y ago
    >Delta has been documented to result in higher viral loads and this is thought to be a factor behind the increased transmissibility. has it ? I've seen this claim made over and over, w/out documentation. I've seen documentation of higher nasal swab loads, but not higher systemic circulating virus. Higher upper respiratory loads (e.g. mucosal) would also lead to increased transmissibility, but not higher waste water levels.
    - mlyle 5y ago
      > has it ? I've seen this claim made over and over, w/out documentation. Very early report on Delta, describing higher loads in oropharyngeal swabs: https://www.medrxiv.org/content/10.1101/2021.07.07.21260122v2.full.pdf https://www.medrxiv.org/content/10.1101/2021.07.07.21260122v... > I've seen documentation of higher nasal swab loads, but not higher systemic circulating virus. You'll have almost no reports of "systemic circulating virus" load, because there's not really an accepted definition for how this measurement would be taken. Plasma concentrations don't appear to be particularly meaningful except in late stages of critical disease. > higher waste water levels. My understanding of the evidence is that fecal loads of Delta are higher than other variants, but not as elevated in comparison to how much throat and nose swabs are elevated. I.e. both statements appear true (higher loading overall, and even higher loading in upper respiratory tissue).
itamarst 5y ago
MA sequences 30% of PCR tests, and has so far found only a single Omicron case...
- incongruity 5y ago
  Couldn’t that potentially be explained by the lag between infection and symptoms with many people being asymptomatic early on while still shedding virus at significant levels? If that’s theory is true, we should see many more tests and identifications of omicron in the coming week.
  - seoaeu 5y ago
    MA does massive amounts of surveillance testing of people who don’t have symptoms. So infections should be picked up by both wastewater testing and PCR tests at about the same time
    - fragmede 5y ago
      Specifically, Boston has a large number of biotech firms and colleges who have the equipment to do PCR testing, as well as the know how to run them.
  - Robotbeat 5y ago
    Still, I think it means we’re likely in the early/mid stages of the exponential curve. I saw estimate of ~5 day doubling time. Meaning that even if 3 weeks ago there were 100 people with Omicron in Boston, there are still only like 800 now. Takes another month or three for it to explode to a large case load.
jointpdf 5y ago
But Delta has been the only game in town for a while now (>99% of cases since late August), so this recent rise in the wastewater viral levels shouldn’t be attributable to a change in the proportion of variants (TBD on Omicron?). https://covid.cdc.gov/covid-data-tracker/#variant-proportions https://covid.cdc.gov/covid-data-tracker/#variant-proportion...
tyrfing 5y ago
The current situation is a handful of confirmed Omicron cases in the US, and a (useless) travel ban to prevent additional cases. Either this data is noise, or that genie isn't just out of the bottle, but ransacked the house while we're arguing over the cork. With a doubling time around 3-5 days and very effective spread to both previously infected and vaccinated, the exact position on that curve is a difference of days. If we're lucky, it's a mild strain - this doesn't have strong evidence yet. If we're unlucky, and it's similar to other strains, we have around a month before things get very bad indeed.
mmatus 5y ago
Lots of good points here! Viral loads and variants are important to keep in mind when interpreting wastewater data. That said, our current best guess is that the rising SARS-CoV-2 concentration in Boston wastewater reflects a real increase in cases. Delta has higher nasal shedding than other variants, but not necessarily higher fecal shedding--the ratio of wastewater concentrations to clinical cases seems pretty constant in our data over time (see our blog post on this topic here: https://biobotanalytics.medium.com/mass-vaccination-delta-and-wastewater-covid-19-data-1c143e3d96a3 https://biobotanalytics.medium.com/mass-vaccination-delta-an...) We know much less about omicron, but it's probably still only a small minority of cases. We're currently sequencing samples of Boston wastewater, so we'll know more about omicron levels in wastewater very soon!

ripper1138 5y ago

Good point. Also keep in mind this is just one location. Would be really cool to see this measured by most cities.

jvmiert 5y ago
We do this in The Netherlands: https://coronadashboard.government.nl/landelijk/rioolwater https://coronadashboard.government.nl/landelijk/rioolwater
- systemBuilder 5y ago
  Wow that is SICK! I think if I had to read viral particles in wastewater for many different diseases at a sewage treatment plant I would go crazy and move to the countryside!
  - yread 5y ago
    There is no "countryside" in the Netherlands
    - OneTimePetes 5y ago
      You can move water-sides though, buy a houseboat and camp out on the lakes..

twofornone 5y ago

Has that been proven or are you just speculating? I don't think increased viral load/shedding is the only mechanism by which a virus becomes more contagious.

mlyle 5y ago
Delta has been documented to result in higher viral loads and this is thought to be a factor behind the increased transmissibility. I don't think anyone knows about the kinetics of Omicron yet. I think the increasing prevalence of Omicron may have a lot more to do with its ability to escape immunity from past infection and increased probability of vaccine breakthrough than any inherent higher transmissibility to those who are immunologically naive.
- anonuser123456 5y ago
  >Delta has been documented to result in higher viral loads and this is thought to be a factor behind the increased transmissibility. has it ? I've seen this claim made over and over, w/out documentation. I've seen documentation of higher nasal swab loads, but not higher systemic circulating virus. Higher upper respiratory loads (e.g. mucosal) would also lead to increased transmissibility, but not higher waste water levels.
  - mlyle 5y ago
    > has it ? I've seen this claim made over and over, w/out documentation. Very early report on Delta, describing higher loads in oropharyngeal swabs: https://www.medrxiv.org/content/10.1101/2021.07.07.21260122v2.full.pdf https://www.medrxiv.org/content/10.1101/2021.07.07.21260122v... > I've seen documentation of higher nasal swab loads, but not higher systemic circulating virus. You'll have almost no reports of "systemic circulating virus" load, because there's not really an accepted definition for how this measurement would be taken. Plasma concentrations don't appear to be particularly meaningful except in late stages of critical disease. > higher waste water levels. My understanding of the evidence is that fecal loads of Delta are higher than other variants, but not as elevated in comparison to how much throat and nose swabs are elevated. I.e. both statements appear true (higher loading overall, and even higher loading in upper respiratory tissue).

itamarst 5y ago

MA sequences 30% of PCR tests, and has so far found only a single Omicron case...

incongruity 5y ago
Couldn’t that potentially be explained by the lag between infection and symptoms with many people being asymptomatic early on while still shedding virus at significant levels? If that’s theory is true, we should see many more tests and identifications of omicron in the coming week.
- seoaeu 5y ago
  MA does massive amounts of surveillance testing of people who don’t have symptoms. So infections should be picked up by both wastewater testing and PCR tests at about the same time
  - fragmede 5y ago
    Specifically, Boston has a large number of biotech firms and colleges who have the equipment to do PCR testing, as well as the know how to run them.
- Robotbeat 5y ago
  Still, I think it means we’re likely in the early/mid stages of the exponential curve. I saw estimate of ~5 day doubling time. Meaning that even if 3 weeks ago there were 100 people with Omicron in Boston, there are still only like 800 now. Takes another month or three for it to explode to a large case load.

jointpdf 5y ago

But Delta has been the only game in town for a while now (>99% of cases since late August), so this recent rise in the wastewater viral levels shouldn’t be attributable to a change in the proportion of variants (TBD on Omicron?). https://covid.cdc.gov/covid-data-tracker/#variant-proportions https://covid.cdc.gov/covid-data-tracker/#variant-proportion...

tyrfing 5y ago

The current situation is a handful of confirmed Omicron cases in the US, and a (useless) travel ban to prevent additional cases. Either this data is noise, or that genie isn't just out of the bottle, but ransacked the house while we're arguing over the cork. With a doubling time around 3-5 days and very effective spread to both previously infected and vaccinated, the exact position on that curve is a difference of days. If we're lucky, it's a mild strain - this doesn't have strong evidence yet. If we're unlucky, and it's similar to other strains, we have around a month before things get very bad indeed.

mmatus 5y ago

Lots of good points here! Viral loads and variants are important to keep in mind when interpreting wastewater data. That said, our current best guess is that the rising SARS-CoV-2 concentration in Boston wastewater reflects a real increase in cases. Delta has higher nasal shedding than other variants, but not necessarily higher fecal shedding--the ratio of wastewater concentrations to clinical cases seems pretty constant in our data over time (see our blog post on this topic here: https://biobotanalytics.medium.com/mass-vaccination-delta-and-wastewater-covid-19-data-1c143e3d96a3 https://biobotanalytics.medium.com/mass-vaccination-delta-an...) We know much less about omicron, but it's probably still only a small minority of cases. We're currently sequencing samples of Boston wastewater, so we'll know more about omicron levels in wastewater very soon!