Jenn Dowd

A propos of nothing, I can’t rule out that my childhood vaccines caused my love of causal inference

The world’s most studied half a million humans humans … just got measured in yet another clever way … looking forward to diving into the data

give me the quadrivalent mRNA flu vaccine right now. put it in me

Experimental mRNA flu vaccine is more effective than conventional flu shot, but causes more side effects

In a phase 3 trial, participants who received the shot were 29% less likely to be diagnosed with flu than those who received a conventional flu shot.

www.cidrap.umn.edu/i...

Unpaid work – the missing link in the gender gap - Understanding Society Long read: unpaid work may affect health through its impact on employment Inequality persists, and housework and caring may be crucial factors

Our latest blog: @anne-mcmunn.bsky.social, Professor of Social Epidemiology at UCL, sets out the evidence on how unpaid work can affect health and inequality through its effect on employment

Wow, you've got to admire the commitment/stubbornness

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Apply now to our next Summer School! 🤝

We are glad to host the Toulouse Summer School in Quantitative Social Sciences from 26 May to 19 June 2026 — a great opportunity for PhD students in economics, political science, and other social sciences.

Application: www.tse-fr.eu/toulouse-sum...

Estimating death rates in complex humanitarian emergencies using the network survival method Abstract. Reliable estimates of death rates in complex humanitarian emergencies are critical for assessing the severity of a crisis and for effectively all

Our new paper develops and tests a network-based method for estimating death rates in complex humanitarian emergencies.

Joint w/ @dennisfeehan.bsky.social and team from Geneva-based NGO @impact-initiatives.bsky.social

academic.oup.com/aje/advance-...

From Baby Bust to ongoing fertility collapse (just kidding) Declining US fertility is back on trend.

29/ Also keep an eye out for new work by @philipncohen.com who is working on a book on this topic: familyinequality.wordpress.com/2024/05/02/f...

The state of the pronatalist movement The pronatalist movement, which claims to be rectifying what some of its members describe as the likely collapse of civilization due to population decline.

28/ A great recent podcast with @karenguzzo.bsky.social www.wbur.org/hereandnow/2... #demography #population @uncpopcenter.bsky.social @popassocamerica.bsky.social

27/ contemporaryfamilies.utah.edu/publications... #demography @popassocamerica.bsky.social

26/ Some additional links: contemporaryfamilies.utah.edu/publications... #demography @popassocamerica.bsky.social

Fears that falling birth rates in US could lead to population collapse are based on faulty assumptions While the changes in population structure that accompany low birth rates are real, the impact of these changes has been dramatically overstated.

25/ And for more on concerns over falling birthrates, follow some great demographers @karenguzzo.bsky.social @lesja.bsky.social @amandajean.bsky.social @shelleydclark.bsky.social @alisongemmill.bsky.social @lauralindberg.bsky.social @srhayford.bsky.social
theconversation.com/fears-that-f...

What Is "Replacement Fertility" Anyway? The fine line between population bomb and population extinction

24/ For more demography & population health content, please consider subscribing to my Substack newsletter!
jenndowd.substack.com/p/what-is-re... #demography

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23/If someone figures out how to make such a bet happen (a la Simon & Ehrlich), let me know. Until then, I recommend investing as much as you can for the people in the world today, & not losing too much sleep over whether this year’s fertility rate is above or below a (somewhat) arbitrary threshold.

22/ #Demography is fun like that-the “stable” populations of the textbooks are rarely seen IRL. While I won't predict how humans will plan their familes hundreds of years from now, I would bet that it’s not going to follow a trend straight down to zero. (What’s going on with this x-axis anyway?)

an elderly woman is holding a crystal ball and saying `` i had a feeling '' . ALT: an elderly woman is holding a crystal ball and saying `` i had a feeling '' .

21/ We don’t have a crystal ball, but projections that global population will peak later this century are certainly feasible. But what happens next will take *hundreds* of years to play out, regardless of whether fertility rates today are above or below “replacement.” #demography

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20/ Today we are less worried about a world with humans stacked upon humans. But we should also be skeptical of projections of population collapse that assume equally unlikely math continuing forever. #demography

a man in a black turtleneck is smiling and says so many people ALT: a man in a black turtleneck is smiling and says so many people

19/ "If growth continued at that rate for about 900 years, there would be some 60,000,000,000,000,000 people on the face of the earth. Sixty million billion people. This is about 100 persons for each square yard of the Earth’s surface, land and sea..."

18/ In his (in) famous the Population Bomb, Paul Ehrlich described what might happen under the “absurd” assumption that human population continued at its pace in the 1960s....

17/Overall it's important to keep in mind that replacement fertility is a theoretical concept, not mathematical destiny. The number 2 (or 2.1) is not a magic tipping point that sends us straight to population collapse, any more than fertility rates higher than 2 led us to infinite population growth.

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16/ Keeping our young people alive & healthy so they have the chance to become parents if they so choose should be one “pro-natalist” policy we can all agree on.
#demography #mortality

15/ My brilliant collaborators @andreatilstra.bsky.social & @polizzan.bsky.social estimated that 200K babies were NOT born between 2010-19 because their potential mothers died compared to if the US had the mortality rates of peer countries. academic.oup.com/pnasnexus/ar... @pnasnexus.org

14/ Sadly, the US has higher mortality at younger ages (mostly due to drugs, accidents, and homicide) than other countries, so we lose more potential mothers & their children.
Figure: Female probability of survival to age 50 years in the United States and 21 other wealthy nations, 1950–2019.

a woman in a red dress is holding a microphone and says " you get a baby and you get a baby " ALT: a woman in a red dress is holding a microphone and says " you get a baby and you get a baby "

13/ So a country that is technically “below replacement” fertility can continue to grow not only by adding new people through immigration (which seems mathematically obvious), but by the added *momentum* of the babies those new residents will have (the real “baby bonuses”!).

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12/ This "momentum" can be amplified through immigration, which tends to attract young adults, increasing the # of people in childbearing years. This means more total births, *even* if immigrants have a similar number of kids as the native-born pop (which is increasingly the case).

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11/ Because of population momentum, fertility (& mortality) rates have to be stable across multiple generations for the elegant math of “replacement” fertility to actually kick in. Spoiler alert: that never happens. #demography

10/ Total births continue to grow, even as births rates go down. Population momentum keeps populations growing for decades beyond when fertility rates fall below “replacement”.
#demography
familyinequality.wordpress.com/2024/05/02/f... @philipncohen.com

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9/ When a big generation (like the baby boom) grows up & becomes parents, birth numbers rise again even if the average family size stays the same. This “echo” of previous growth isn’t about people having more kids, it’s about more people having kids. #demography