5 ms·

Global circulation of influenza viruses in 2020

64 points by dustinmoris 6y ago

rossdavidh 6y ago
Well, not _completely_: "A total of 172 specimens were positive for influenza viruses, of which 108 (62.8%) were typed as influenza A and 64 (37.2%) as influenza B."
rossdavidh 6y ago
I mean, it certainly looks lower, but if you look at the same time in 2019, it was very low then as well. If it still looks this low in 10 weeks, I'll be impressed.
jmnicolas 6y ago
I can say that for march to may in France everybody that died with COVID like symptoms was counted as a COVID fatality since we didn't have enough tests. So it could very well be that many people died of the flu but were counted as COVID, we'll never know.
- dragontamer 6y ago
  But this article is using flu-tests to test for specimens of the flu. Why would a lack of COVID tests mess up the flu-tests that they're using?
  - sidlls 6y ago
    He’s saying the published stats could be off because of a bias toward diagnosing flu deaths as COVID deaths without testing for COVID. That is, the suggestion seems to me to be that the sampling methodology may underrepresent flu. I don’t know that I agree, but I suppose it’s possible.
    - dragontamer 6y ago
      The idea that 172 different strains of the Flu virus can be accurately detected and tracked, but suddenly adding a 173rd virus (COVID19) to the mix would mess up their survey seems a bit ridiculous to me. ----- These flu-surveys are extremely important for designing next year's flu vaccine. There are hundreds, if not thousands, of flu strains, since that virus is constantly evolving. But the flu vaccine can only protect against 5ish strains. Some strains (in particular: Flu TypeA) are known to spread much faster than others (ie: Flu TypeC). So even if TypeC is more common, maybe Flu TypeA is prioritized because of the risk of it becoming a pandemic a year out.
  - rezeroed 6y ago
    They didn't perform flu tests on all "covid" deaths.
    - projektfu 6y ago
      But the vast majority of samples are coming from people who will ultimately survive, but who have respiratory illness. Anyhow, scientists have considered testing bias. https://www.cdc.gov/mmwr/volumes/69/wr/pdfs/mm6937a6-H.pdf https://www.cdc.gov/mmwr/volumes/69/wr/pdfs/mm6937a6-H.pdf “Initially, declines in influenza virus activity were attributed to decreased testing, because persons with respiratory symptoms were often preferentially referred for SARS-CoV-2 assessment and testing. However, renewed efforts by public health officials and clinicians to test samples for influenza resulted in adequate numbers tested and detection of little to no influenza virus.”
    - Uberphallus 6y ago
      Most people don't die from flu, so that means it might be underrepresented by 0.1%. If anything, there's less testing for flu because of covid. But nonetheless, this is sampling, not testing, the WHO performs consistent randomized sampling over time to keep the data meaningful. If they just were based on testing of reported flu cases the data would be heavily biased and basically useless in tracking the disease.
- spirobel 6y ago
  how dare you :-)
- gamegod 6y ago
  This is completely irrelevant to the linked data.
  - deleted 6y ago
    [deleted]
- throwaway2245 6y ago
  While testing for flu in the global sample is indeed down 21% compared to last year, positive cases are (currently) down 97%. From their fortnightly report of 28 October 2019: "data to FluNet for the time period from 30 September 2019 to 13 October 2019. The WHO GISRS laboratories tested more than 102881 specimens during that time period. 5005 were positive for influenza viruses" And of 26 October 2020: "...from 28 September 2020 to 11 October 2020. The WHO GISRS laboratories tested more than 81257 specimens during that time period. A total of 172 specimens were positive for influenza viruses"
- thebruce87m 6y ago
  Excess mortality data is here: https://www.euromomo.eu/graphs-and-maps/ https://www.euromomo.eu/graphs-and-maps/ Looks like minimal deaths from flu during normal flu months in 2020 followed by a large spike (COVID). The spike appears at the end of the flu season, but the previous patterns suggest you should have been seeing excess mortality earlier if flu was bad this year, so my money is on minimal flu deaths.
gazelle21 6y ago
A lot of people aren’t going to doctor’s offices right now. I personally know of 3 people with flu like symptoms who refused to go to the doctor for a variety of reasons, but one mentioned being a outcast for possibly having COVID 19.
- cm2187 6y ago
  Not sure why you are getting flagged. People not seeking medical assistance could be a reason why the sampling isn’t collecting any flu case.
  - Uberphallus 6y ago
    Because they're not reported cases, but sampled cases, so whether reported goes up or down doesn't really matter as the sampling is consistent.
    - jtbayly 6y ago
      Saying that they are sampled cases doesn't mean anything about whether that number can be effected by other variables. Fewer tests would result in lower total positive results. So would people with flu symptoms actively avoiding being tested. Whether that's happening is an entirely valid question.
      - Uberphallus 6y ago
        Check this link and have a blast[0] This year, for example in the North America region, there have been 26,000 samples for weeks 35 and 36. Around 40 positives. Last year, 27,000 in the same period. Around 1,000 positives. As I said in multiple posts already, the WHO tries to keep consistent sampling to keep the data meaningful. It's literally their job. [0] https://apps.who.int/flumart/Default?ReportNo=12 https://apps.who.int/flumart/Default?ReportNo=12
        cm2187 6y ago
        But what the parent is saying is that lots of people who have fever may be self-isolating and not seeking medical assistance thinking it is Covid (as many of the symptoms are identical), whereas they may have seen a doctor a year before. In this case, the population that doctors see that have flu-like symptoms (as opposed to other symptoms) may be less. So it doesn't matter how many samples you take in that population, you would get less flu patients. All speculation. But just a plausible explanation.
nfsail 6y ago
If you consult the previous years, the graph is the same. The conclusion is not accurate.
CerealFounder 6y ago
This feels like a sensible conclusion. With borders closed and human to human contact relegated to only your closest family the whole annual mechanism for spreading flu (often season and triggered by air travel) goes to zero.
acqq 6y ago
The title on HN is probably invented by the submitter, which is misleading and doesn‘t match the HN policy. The title on the page: “Influenza: FluNet Summary 26 October 2020 Source: Laboratory confirmed data from the Global Influenza Surveillance and Response System (GISRS).” It‘s also possible that those who would normally participate in the Global Influenza Surveillance and Response System just weren‘t able to do what was normally done in a non-pandemics year. The page doesn’t present any explanation.
- dustinmoris 6y ago
  Apologies, I re-phrased the title to be accurate.
greggeter 6y ago
Which means there's a huge flu season in our future.
hexo 6y ago
The statement is not true at all.
- troublesom 6y ago
  On what do you base that?
fny 6y ago
Reading the graph posted, you may think we stopped tracking the flu. However, it's not clear yet whether that is the case, and the charts from 2019 show that. Here are the charts for 2019 and 2020 in the US*: https://imgur.com/a/HvBJoj2 https://imgur.com/a/HvBJoj2 (Note the axes are on different time scales unfortunately). They are very similar with two major exceptions. 1. Week 13, about March 23rd, there is a dip lower, presumably due to the lock downs. 2. There was no activity throughout this spring and summer, but that's typically the case as the 2019 chart shows. 2020 is even lower (virtually no cases). While this could be due to lack of reporting, it could also be due to social distancing and masking. We are currently in Week 44 of 2020. During week 44 of 2019 cases began to uptick slightly and then increased parabolically into the winter. We should expect the same in 2020. And this will be how we really know if flu testing is suppressed. Anyone claiming anything otherwise is speculating. Anecdotally, my sister caught a bug recently that tested negative for COVID, and the physician suspected the flu. However, he couldn't test for flu since there was no capacity for flu testing. Source: https://apps.who.int/flumart/Default?ReportNo=7 https://apps.who.int/flumart/Default?ReportNo=7
- neogodless 6y ago
  Note the different horizontal axes been the graphs. The top one goes back up after week 43/44 which is about where the bottom one ends. I know your text describes this but it's easy to look at the graphs and miss!
  - ddoran 6y ago
    I was about to post the same but both horizontal and vertical axes are different scales.
  - fny 6y ago
    I just updated my comment to clarify too. Unfortunately, the WHO only plots data for weeks that have occurred, so there's no way to extend match the two axes.
- deleted 6y ago
  [deleted]
devy 6y ago
The title is very catchy and misleading. The WHO's virus circulation graph and the text did NOT describe it as "Completely Disappeared in 2020." It did reporting having seen very minuscule amount of flu virus detected, instead. https://www.who.int/influenza/gisrs_laboratory/updates/flunet_globalviruscirculation_20201023.PNG https://www.who.int/influenza/gisrs_laboratory/updates/flune... Edit: now the title has been updated, it's more accurate
NoOneNew 6y ago
81k is kind of a shitty sample size to make a sweeping worldwide judgement for 7+billion. Next part, since the focus of 2020 was Covid testing, I'm pretty sure flu testing resources were lessened in the process, if not borderline ignored. At what point was it okay to judge a population on 0.0000001157142% sample size? While I'm not a fan of the WHO anymore, to be fair to them, where the hell do they say the flu disappeared? This title is disingenuous.
- anoncake 6y ago
  Properly selected, 1k is a sufficient sample size for any population.
- drivebycomment 6y ago
  This is a common misunderstanding of the statistics. The sample size is more a function of the target variance and the confidence level, not as much on the overall population. 81k, if picked properly, would be sufficient for their purpose.
  - NoOneNew 6y ago
    Okay, what are the rules to determining the proper sample? How can you objectively determine if one sample is better or worse than another?
    - drivebycomment 6y ago
      If you are asking about sample size selection, you can use: http://www.tools4dev.org/resources/how-to-choose-a-sample-size http://www.tools4dev.org/resources/how-to-choose-a-sample-si... If you want to evaluate quality of a sample, that's an entirely different issue. You may want to look up different sampling methods.
m-app 6y ago
The actual WHO Influenza update [1] rightfully adds a disclaimer: > The current influenza surveillance data should be interpreted with caution as the ongoing COVID-19 pandemic have influenced to varying extents health seeking behaviours, staffing/routines in sentinel sites, as well as testing priorities and capacities in Member States. The various hygiene and physical distancing measures implemented by Member States to reduce SARS-CoV-2 virus transmission have likely played a role in reducing influenza virus transmission. But also: > Globally, despite continued or even increased testing for influenza in some countries influenza activity remained at lower levels than expected for this time of the year. [1]: https://www.who.int/influenza/surveillance_monitoring/updates/latest_update_GIP_surveillance/en/ https://www.who.int/influenza/surveillance_monitoring/update...
scottlocklin 6y ago
Classic sample bias; the hospitals were closed in anticipation of everyone's weird fantasy of tens of thousands of people hooked up to breathing machines, so very little flu testing was actually done. All the indications were that it was set to be a terrible flu season[0]. Of course it could be that Corona-chan was circulating before it was broadly recognized, but that would be public health nitwits admitting their mistakes: something that doesn't seem to happen, ever. [0] https://time.com/5758953/flu-season-2019-2020/ https://time.com/5758953/flu-season-2019-2020/
dcolkitt 6y ago
About a month ago, I came down with an upper respiratory illness that felt like a severe flu. Covid nasal swab test was taken 24 hours after first symptoms appeared, and came back negative. Therefore I assumed it was flu. However given the supposedly very low base rate of flu during the current season, is it more likely from a Bayesian perspective that the Covid test was a false negative?
hikerclimb 6y ago
Hoping for more deadly viruses to spread.

64 points by dustinmoris 6y ago

Well, not _completely_: "A total of 172 specimens were positive for influenza viruses, of which 108 (62.8%) were typed as influenza A and 64 (37.2%) as influenza B."

rossdavidh 6y ago

I mean, it certainly looks lower, but if you look at the same time in 2019, it was very low then as well. If it still looks this low in 10 weeks, I'll be impressed.

jmnicolas 6y ago

I can say that for march to may in France everybody that died with COVID like symptoms was counted as a COVID fatality since we didn't have enough tests. So it could very well be that many people died of the flu but were counted as COVID, we'll never know.

dragontamer 6y ago
But this article is using flu-tests to test for specimens of the flu. Why would a lack of COVID tests mess up the flu-tests that they're using?
- sidlls 6y ago
  He’s saying the published stats could be off because of a bias toward diagnosing flu deaths as COVID deaths without testing for COVID. That is, the suggestion seems to me to be that the sampling methodology may underrepresent flu. I don’t know that I agree, but I suppose it’s possible.
  - dragontamer 6y ago
    The idea that 172 different strains of the Flu virus can be accurately detected and tracked, but suddenly adding a 173rd virus (COVID19) to the mix would mess up their survey seems a bit ridiculous to me. ----- These flu-surveys are extremely important for designing next year's flu vaccine. There are hundreds, if not thousands, of flu strains, since that virus is constantly evolving. But the flu vaccine can only protect against 5ish strains. Some strains (in particular: Flu TypeA) are known to spread much faster than others (ie: Flu TypeC). So even if TypeC is more common, maybe Flu TypeA is prioritized because of the risk of it becoming a pandemic a year out.
- rezeroed 6y ago
  They didn't perform flu tests on all "covid" deaths.
  - projektfu 6y ago
    But the vast majority of samples are coming from people who will ultimately survive, but who have respiratory illness. Anyhow, scientists have considered testing bias. https://www.cdc.gov/mmwr/volumes/69/wr/pdfs/mm6937a6-H.pdf https://www.cdc.gov/mmwr/volumes/69/wr/pdfs/mm6937a6-H.pdf “Initially, declines in influenza virus activity were attributed to decreased testing, because persons with respiratory symptoms were often preferentially referred for SARS-CoV-2 assessment and testing. However, renewed efforts by public health officials and clinicians to test samples for influenza resulted in adequate numbers tested and detection of little to no influenza virus.”
  - Uberphallus 6y ago
    Most people don't die from flu, so that means it might be underrepresented by 0.1%. If anything, there's less testing for flu because of covid. But nonetheless, this is sampling, not testing, the WHO performs consistent randomized sampling over time to keep the data meaningful. If they just were based on testing of reported flu cases the data would be heavily biased and basically useless in tracking the disease.
spirobel 6y ago
how dare you :-)
gamegod 6y ago
This is completely irrelevant to the linked data.
- deleted 6y ago
  [deleted]
throwaway2245 6y ago
While testing for flu in the global sample is indeed down 21% compared to last year, positive cases are (currently) down 97%. From their fortnightly report of 28 October 2019: "data to FluNet for the time period from 30 September 2019 to 13 October 2019. The WHO GISRS laboratories tested more than 102881 specimens during that time period. 5005 were positive for influenza viruses" And of 26 October 2020: "...from 28 September 2020 to 11 October 2020. The WHO GISRS laboratories tested more than 81257 specimens during that time period. A total of 172 specimens were positive for influenza viruses"
thebruce87m 6y ago
Excess mortality data is here: https://www.euromomo.eu/graphs-and-maps/ https://www.euromomo.eu/graphs-and-maps/ Looks like minimal deaths from flu during normal flu months in 2020 followed by a large spike (COVID). The spike appears at the end of the flu season, but the previous patterns suggest you should have been seeing excess mortality earlier if flu was bad this year, so my money is on minimal flu deaths.

gazelle21 6y ago

A lot of people aren’t going to doctor’s offices right now. I personally know of 3 people with flu like symptoms who refused to go to the doctor for a variety of reasons, but one mentioned being a outcast for possibly having COVID 19.

cm2187 6y ago
Not sure why you are getting flagged. People not seeking medical assistance could be a reason why the sampling isn’t collecting any flu case.
- Uberphallus 6y ago
  Because they're not reported cases, but sampled cases, so whether reported goes up or down doesn't really matter as the sampling is consistent.
  - jtbayly 6y ago
    Saying that they are sampled cases doesn't mean anything about whether that number can be effected by other variables. Fewer tests would result in lower total positive results. So would people with flu symptoms actively avoiding being tested. Whether that's happening is an entirely valid question.
    - Uberphallus 6y ago
      Check this link and have a blast[0] This year, for example in the North America region, there have been 26,000 samples for weeks 35 and 36. Around 40 positives. Last year, 27,000 in the same period. Around 1,000 positives. As I said in multiple posts already, the WHO tries to keep consistent sampling to keep the data meaningful. It's literally their job. [0] https://apps.who.int/flumart/Default?ReportNo=12 https://apps.who.int/flumart/Default?ReportNo=12
      - cm2187 6y ago
        But what the parent is saying is that lots of people who have fever may be self-isolating and not seeking medical assistance thinking it is Covid (as many of the symptoms are identical), whereas they may have seen a doctor a year before. In this case, the population that doctors see that have flu-like symptoms (as opposed to other symptoms) may be less. So it doesn't matter how many samples you take in that population, you would get less flu patients. All speculation. But just a plausible explanation.

nfsail 6y ago

If you consult the previous years, the graph is the same. The conclusion is not accurate.

CerealFounder 6y ago

This feels like a sensible conclusion. With borders closed and human to human contact relegated to only your closest family the whole annual mechanism for spreading flu (often season and triggered by air travel) goes to zero.

acqq 6y ago

The title on HN is probably invented by the submitter, which is misleading and doesn‘t match the HN policy. The title on the page: “Influenza: FluNet Summary 26 October 2020 Source: Laboratory confirmed data from the Global Influenza Surveillance and Response System (GISRS).” It‘s also possible that those who would normally participate in the Global Influenza Surveillance and Response System just weren‘t able to do what was normally done in a non-pandemics year. The page doesn’t present any explanation.

dustinmoris 6y ago
Apologies, I re-phrased the title to be accurate.

greggeter 6y ago

Which means there's a huge flu season in our future.

hexo 6y ago

The statement is not true at all.

troublesom 6y ago
On what do you base that?

fny 6y ago

Reading the graph posted, you may think we stopped tracking the flu. However, it's not clear yet whether that is the case, and the charts from 2019 show that. Here are the charts for 2019 and 2020 in the US*: https://imgur.com/a/HvBJoj2 https://imgur.com/a/HvBJoj2 (Note the axes are on different time scales unfortunately). They are very similar with two major exceptions. 1. Week 13, about March 23rd, there is a dip lower, presumably due to the lock downs. 2. There was no activity throughout this spring and summer, but that's typically the case as the 2019 chart shows. 2020 is even lower (virtually no cases). While this could be due to lack of reporting, it could also be due to social distancing and masking. We are currently in Week 44 of 2020. During week 44 of 2019 cases began to uptick slightly and then increased parabolically into the winter. We should expect the same in 2020. And this will be how we really know if flu testing is suppressed. Anyone claiming anything otherwise is speculating. Anecdotally, my sister caught a bug recently that tested negative for COVID, and the physician suspected the flu. However, he couldn't test for flu since there was no capacity for flu testing. Source: https://apps.who.int/flumart/Default?ReportNo=7 https://apps.who.int/flumart/Default?ReportNo=7

neogodless 6y ago
Note the different horizontal axes been the graphs. The top one goes back up after week 43/44 which is about where the bottom one ends. I know your text describes this but it's easy to look at the graphs and miss!
- ddoran 6y ago
  I was about to post the same but both horizontal and vertical axes are different scales.
- fny 6y ago
  I just updated my comment to clarify too. Unfortunately, the WHO only plots data for weeks that have occurred, so there's no way to extend match the two axes.
deleted 6y ago
[deleted]

devy 6y ago

The title is very catchy and misleading. The WHO's virus circulation graph and the text did NOT describe it as "Completely Disappeared in 2020." It did reporting having seen very minuscule amount of flu virus detected, instead. https://www.who.int/influenza/gisrs_laboratory/updates/flunet_globalviruscirculation_20201023.PNG https://www.who.int/influenza/gisrs_laboratory/updates/flune... Edit: now the title has been updated, it's more accurate

NoOneNew 6y ago

81k is kind of a shitty sample size to make a sweeping worldwide judgement for 7+billion. Next part, since the focus of 2020 was Covid testing, I'm pretty sure flu testing resources were lessened in the process, if not borderline ignored. At what point was it okay to judge a population on 0.0000001157142% sample size? While I'm not a fan of the WHO anymore, to be fair to them, where the hell do they say the flu disappeared? This title is disingenuous.

anoncake 6y ago
Properly selected, 1k is a sufficient sample size for any population.
drivebycomment 6y ago
This is a common misunderstanding of the statistics. The sample size is more a function of the target variance and the confidence level, not as much on the overall population. 81k, if picked properly, would be sufficient for their purpose.
- NoOneNew 6y ago
  Okay, what are the rules to determining the proper sample? How can you objectively determine if one sample is better or worse than another?
  - drivebycomment 6y ago
    If you are asking about sample size selection, you can use: http://www.tools4dev.org/resources/how-to-choose-a-sample-size http://www.tools4dev.org/resources/how-to-choose-a-sample-si... If you want to evaluate quality of a sample, that's an entirely different issue. You may want to look up different sampling methods.

m-app 6y ago

The actual WHO Influenza update [1] rightfully adds a disclaimer: > The current influenza surveillance data should be interpreted with caution as the ongoing COVID-19 pandemic have influenced to varying extents health seeking behaviours, staffing/routines in sentinel sites, as well as testing priorities and capacities in Member States. The various hygiene and physical distancing measures implemented by Member States to reduce SARS-CoV-2 virus transmission have likely played a role in reducing influenza virus transmission. But also: > Globally, despite continued or even increased testing for influenza in some countries influenza activity remained at lower levels than expected for this time of the year. [1]: https://www.who.int/influenza/surveillance_monitoring/updates/latest_update_GIP_surveillance/en/ https://www.who.int/influenza/surveillance_monitoring/update...

scottlocklin 6y ago

Classic sample bias; the hospitals were closed in anticipation of everyone's weird fantasy of tens of thousands of people hooked up to breathing machines, so very little flu testing was actually done. All the indications were that it was set to be a terrible flu season[0]. Of course it could be that Corona-chan was circulating before it was broadly recognized, but that would be public health nitwits admitting their mistakes: something that doesn't seem to happen, ever. [0] https://time.com/5758953/flu-season-2019-2020/ https://time.com/5758953/flu-season-2019-2020/

dcolkitt 6y ago

About a month ago, I came down with an upper respiratory illness that felt like a severe flu. Covid nasal swab test was taken 24 hours after first symptoms appeared, and came back negative. Therefore I assumed it was flu. However given the supposedly very low base rate of flu during the current season, is it more likely from a Bayesian perspective that the Covid test was a false negative?

hikerclimb 6y ago

Hoping for more deadly viruses to spread.