“๐–๐š๐ข๐ญ, ๐š๐ฌ๐ฒ๐ฆ๐ฉ๐ญ๐จ๐ฆ๐š๐ญ๐ข๐œ ๐ฌ๐ฉ๐ซ๐ž๐š๐ ๐๐ข๐๐ง’๐ญ ๐จ๐œ๐œ๐ฎ๐ซ ๐š๐ญ ๐š๐ฅ๐ฅ? ๐ˆ๐ฌ ๐ญ๐ก๐š๐ญ ๐ญ๐ซ๐ฎ๐ž?” ๐๐ž๐ฐ๐š๐ซ๐ž ๐จ๐Ÿ ๐œ๐ก๐ž๐ซ๐ซ๐ฒ-๐ฉ๐ข๐œ๐ค๐ข๐ง๐  ๐š๐ง๐ ๐›๐ข๐ง๐š๐ซ๐ฒ-๐ญ๐ก๐ข๐ง๐ค๐ข๐ง๐ .


Nope, it’s not true and unfortunately is being touted as anti-lockdown justification (BTW, no one is calling for lockdowns unless they are absolutely necessary. We can chew gum (take precautions) and walk at the same time (remain relatively open).

๐Ž๐ค, ๐ก๐ž๐ซ๐ž ๐ฐ๐ž ๐ ๐จ:

โœ… ๐๐ˆ๐‚๐“๐”๐‘๐„ ๐Ÿ -JAMA (Journal of the American Medical Association) is a top-tiered, premier, peer-reviewed journal in the US. They published a meta-analysis where they combined 54 papers which included 77,000 participants. The ๐ฉ๐ฎ๐ซ๐ฉ๐จ๐ฌ๐ž ๐จ๐Ÿ ๐ญ๐ก๐ž ๐ฌ๐ญ๐ฎ๐๐ฒ was to assess the overall household secondary attack rate (who got infected from a sick household member) and found that households are important “venues for transmission, even in areas where community transmission is reduced”.


Then the cherry-picking started. In epidemiology terms, we call that bias, a fallacy, a “that’s not what the study said”. The headlines that you have probably seen are shown in the opening picture of this post – all of the sudden, people were concluding asymptomatic spread did not happen at all, lockdowns are unnecessary, and masks don’t work. I also saw people using this study to conclude we don’t need masks since you aren’t infectious until you start exhibiting symptoms. hashtag-face-palm. Hold up. It’s like saying, “The study concludes the water is purple” and the headlines are, “So, you’re saying it’s red.”

โœ… ๐๐ˆ๐‚๐“๐”๐‘๐„ ๐Ÿ – One of the lead authors, Dr. Natalie Dean (a top expert and highly respected biostatistician) responded to what the study actually said. The study concluded that the secondary attack rate (this is the chance that an infected person will infect others in the home) was 18%.

โœ… ๐๐ˆ๐‚๐“๐”๐‘๐„ ๐Ÿ‘ – They also did a SUPPLEMENT SUB-ANALYSIS on a much smaller group of 31 studies to try to figure out how much of the spread to other household members occurred with the index cases was asymptomatic, pre-symptomatic, or symptomatic. Of the 31 studies, only FOUR (4) studies had data on whether or not the index cases were asymptomatic at the time of other household members getting sick. FOUR studies is not a lot. Also, they were not able to fully separate out fully asymptomatic cases from pre-symptomatic cases because of the small group of studies (in epidemiology, we call this a small sample size).
๐–๐ก๐ž๐ซ๐ž ๐๐ข๐ ๐ญ๐ก๐ž ๐œ๐ก๐ž๐ซ๐ซ๐ฒ ๐ฉ๐ข๐œ๐ค๐ข๐ง๐  ๐ก๐š๐ฉ๐ฉ๐ž๐ง? ๐…๐ซ๐จ๐ฆ ๐ญ๐ก๐š๐ญ ๐ฌ๐ฎ๐ฉ๐ฉ๐ฅ๐ž๐ฆ๐ž๐ง๐ญ๐š๐ฅ ๐ฌ๐ฎ๐›-๐š๐ง๐š๐ฅ๐ฒ๐ฌ๐ข๐ฌ ๐œ๐จ๐ง๐œ๐ฅ๐ฎ๐ฌ๐ข๐จ๐ง ๐จ๐Ÿ ๐Ÿ’ ๐ฌ๐ญ๐ฎ๐๐ข๐ž๐ฌ. ๐๐Ž๐“ ๐ญ๐ก๐ž ๐Ÿ๐ฎ๐ฅ๐ฅ ๐ฌ๐ญ๐ฎ๐๐ฒ ๐จ๐Ÿ ๐Ÿ•๐Ÿ•,๐ŸŽ๐ŸŽ๐ŸŽ. ๐ฎ๐ ๐ก, ๐ฎ๐ ๐ก, ๐ฎ๐ ๐ก.

โœ… ๐๐ˆ๐‚๐“๐”๐‘๐„ ๐Ÿ’ – What did the study say? Households continue to be a risk to other family members. The study did find in the sub-study that the secondary attack rate was lower for asymptomatic/pre-symptomatic persons than symptomatic people. Yes, that makes sense. But, like Dr. Dean (the author) said in the picture, “even if something occurs less frequently, it can still play an important role in the overall epidemic. If an asymptomatic person is far less infectious but has far more contacts than someone home with a fever, it can come out in the wash.” Yep.

โœ… What was concluded as a slant from the anti-lockdown crew (which is synonymous with the Great Barrington Declaration group, Dr. Atlas’ thoughts, and lots of “masks-don’t-work” crew)? What was concluded was nothing about households. The results were generalized to ALL asymptomatic spread for ALL people based on the supplement of 4 studies.

โœ… In epidemiology, we call that “overgeneralization” – a certain type of bias. This occurs when a study says that people with blonde hair between the ages of 20-30 who live in a 3-bedroom house shouldn’t eat candy – and, the conclusions in headlines say that all people shouldn’t eat candy. It was OVERgeneralized to who was actually in the study and what the study actually said. It’s like the movie line, “So, you’re saying there’s a chance!”.

๐“๐ก๐ž ๐ฌ๐ญ๐ฎ๐๐ฒ ๐๐ข๐ ๐ง๐จ๐ญ ๐ฌ๐š๐ฒ ๐ญ๐ก๐ž ๐ซ๐ข๐ฌ๐ค ๐ฐ๐š๐ฌ ๐ŸŽ% ๐Ÿ๐จ๐ซ ๐š๐ฌ๐ฒ๐ฆ๐ฉ๐ญ๐จ๐ฆ๐š๐ญ๐ข๐œ/๐ฉ๐ซ๐ž-๐ฌ๐ฒ๐ฆ๐ฉ๐ญ๐จ๐ฆ๐š๐ญ๐ข๐œ ๐ญ๐ซ๐š๐ง๐ฌ๐ฆ๐ข๐ฌ๐ฌ๐ข๐จ๐ง ๐จ๐ซ ๐š๐ง๐ฒ๐ญ๐ก๐ข๐ง๐  ๐š๐›๐จ๐ฎ๐ญ ๐ฅ๐จ๐œ๐ค๐๐จ๐ฐ๐ง๐ฌ.

โœ… In today’s world, this overgeneralization is really frustrating to many of us scientists who took entire courses on the concept. It is also sneaky how it makes headlines to fit an agenda. The cherry-picking that occurs can fit anyone’s mentality and worldview on the pandemic right now. You can cherry-pick data to fit what you want – but, it’s not simply a matter of fact-checking and moving on. People are using this to justify binary thinking. This means they are using the cherry-picked-biased-overgeneralized statements to fit what they want – and, conclude “Therefore, we should open fully” or “see, I told you lockdowns were awful” or “see, I told you ….”

This builds a false narrative around the virus that isn’t just about what you believe. It has real-world implications to those beliefs. (I’ve written extensively on the false narrative – see the pinned post Table O’ Contents on FB for that).


The false narrative leads to behavior changes in mask wearing or taking precautions. Which affects all of us, our hospitals, and our communities. Then the reality in our hospitals are our fact-checker – but, not with words anymore. With people’s lives.

โœ… So, be very cautious about binary-thinking and overgeneralization-cherry-picking. Go to the original source to see if the study actually said what you are reading in the headlines. Better yet, ask a scientist who can help interpret the study, identify biases and overgeneralization, and be super-cautious on political slants and agendas. As an example, these headlines only showed up on certain websites and news outlets. All of them that I saw had a political slant to it.

I guarantee, if ANY study comes out and says masks don’t work, we don’t need to distance any more, or we can party like it’s 1999, we (epidemiologists, Dr. Fauci, the surgeon general, ICU-frontline-healthcare workers, etc) will be first to tell you. Until then, be careful about binary-thinking and cherry-picking in this pandemic. There is a middle-ground that is much safer than the pendulum swings of agendas.

Post #2 coming up later today about the new mutation and why that matters right now.

-Friendly neighbor epidemiologist

***I’m linking to some posts I’ve already written on the Great Barrington Declaration versus John Snow Memorandum if you want to read more on the anti-lockdown conversation. And, other posts on the economy versus lock-down conversation. These are examples of binary-thinking.

๐“๐‡๐„ ๐†๐‘๐„๐€๐“ ๐๐€๐‘๐‘๐ˆ๐๐†๐“๐Ž๐ ๐ƒ๐„๐๐€๐“๐„ ๐€๐๐ƒ ๐“๐‡๐„ ๐‰๐Ž๐‡๐ ๐’๐๐Ž๐– ๐Œ๐„๐Œ๐Ž๐‘๐€๐๐ƒ๐”๐Œ:

1. GBD Part 1 – https://tinyurl.com/y3spdcpu2.

GBD Part 2 – https://tinyurl.com/y4qywa9m3.

John Snow Memorandum Part 1 – https://tinyurl.com/y5r9wxzd4.

John Snow Memorandum Part 2 – https://tinyurl.com/y4ckxr9w

๐„๐‚๐Ž๐๐Ž๐Œ๐˜

1. Pro-health means pro-economy: We can keep businesses open and people safe https://tinyurl.com/yy48tzaa

2. Itโ€™s not jobs versus lives. One of my FAVORITE articles.- https://tinyurl.com/y42mqcug

3. Re-opening cautiously- https://tinyurl.com/y2jjvw9w

๐’๐Ž๐”๐‘๐‚๐„๐’:

Original JAMA article: https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2774102

Another great article on asymptomatic spread: https://www.nature.com/articles/d41586-020-03141-3

When are people contagious? https://tinyurl.com/y27rfryy

This Post Has One Comment

  1. Thank you so much for this analysis. A group in South Africa (Panda) consisting of a group of actuaries are using this argument to try and convince people that lockdowns, masks, etc are not working. I appreciate the way in which you explain the concepts.

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