Jenn Dowd

Light blue background. Young woman with dark hair makes a sign of strength with her arm and she has a vaccine bandaid on her upper arm. It says "The HPV Vaccine Works!"

The HPV vaccine is doing what had been promised.
17 years after it became available, HPV infections decreased significantly in vaccinated people and unvaccinated people because of herd immunity. buff.ly/WvjQ1BS

h/t @boghuma.bsky.social

#medsky #pedsky 🛟🧪

With apologies to Jimmy Buffett....
jenndowd.substack.com/p/wasting-yo... #episky #medsky #dementia

Nice job (maybe too nice?) not calling anyone out specifically 😂

Why the total fertility rate doesn’t necessarily tell us the number of births women eventually have The fertility rate is commonly confused with the eventual number of births per woman. This can result in misinterpreting the impact of policies and trends over time.

New Bluesky rule: you can’t post a figure showing dramatic decline in the TFR without either explaining what TFR can, and can’t tell us, or posting the excellent explainer by @scientificdiscovery.dev on the topic.

How many people died of COVID? We likely undercounted, not overcounted COVID deaths

10/ We *do* in fact have a good idea of how many people in the US died of COVID... around 1.2 million. #episky #demography #medsky #policysky jenndowd.substack.com/p/how-many-p...

Don’t You Forget About Me(asles): The Virus That Erases Immune Memory Measles vaccination protects your entire immune history.

9/ Reason 101 why you don't want to get measles: jenndowd.substack.com/p/dont-you-f... #idsky #immunosky #episky

Did the Pandemic Really Age Our Brains? A closer look at the evidence.

8/ Did the pandemic age our brains? Maybe, but this paper doesn't show that... jenndowd.substack.com/p/did-the-pa... #episky

Can You Pay to Get Taller, Smarter Embryos? Genetic prediction is not as good as you think.

7/ The noisy statistics behind embryo selection: jenndowd.substack.com/p/can-you-pa... #genetics #medsky #episky

Do additional COVID vaccines really help? We've accumulated a lot of scientific evidence in the last few years.

6/ Do additional COVID shots really help? (I really can't help myself with Princess Bride memes): jenndowd.substack.com/p/do-additio... #episky #medsky #idsky #publichealth

Is our population collapsing? Throwing some cold water on "population panic"

5/ And responding to the current birth rate panic: jenndowd.substack.com/p/is-our-pop... #demography

There Were Still Old People When Life Expectancy Was 35. A demography myth that won't die

4/ This myth that I just heard one too many times on the TikTok: jenndowd.substack.com/p/there-were... #demography

Can the Shingles Vaccine Prevent Dementia? Signs point to yes (at least for women).

3/ Surprising links between the shingles vaccine and dementia: jenndowd.substack.com/p/can-the-sh... #dementia #episky #causalsky #idsky

Oh Oh Oh Ozempic-is there anything GLP-1 drugs can’t do? A new study maps wide-ranging benefits (and risks) of GLP-1 drugs.

2/ Some highlights: Is there anything Ozempic can't do?
jenndowd.substack.com/p/oh-oh-oh-o... #episky #medsky

1/ BlueSky peeps-I can't believe it's been 6 months since my 1st Data for Health post. From Ozempic to the shingles vaccine to population collapse, you guys have been game for it all. Please consider sharing to help me reach more people w/ accessible, data-driven science info!🙏 jenndowd.substack.com

Can't tell you how much that support means to me, THANK YOU!

📢 The #REVES2026 Call for Papers is OPEN!

Join us to discuss about aging, longevity, and population health — with a focus on health expectancy and policy impact!

📆 11–13 March 2026|Tokyo, Japan

🔗 www.reves2026.com

📌 Submit by 30 November 2025

reves-network.org

#demography
#LifeExpectancy

Pure bloodlines? Ancestral homelands? DNA science says no. — Harvard Gazette Geneticist explains recent analyses made possible by tech advances show human history to be one of mixing, movement, displacement.

“The big perspective change from ancient DNA study is that people living today are almost never the descendants of the people in the same place thousands of years before”

news.harvard.edu/gazette/stor...

🤌

In case this hasn't made it into your feeds, @lesja.bsky.social @karenguzzo.bsky.social @shelleydclark.bsky.social @drjenndowd.bsky.social

Going straight into my lecture slides for this quarter!

ha ha yes survey experiments not super realistic! But interesting from the perspective of how much to believe the traditional out-of-context survey responses about desired family size.

Why the total fertility rate doesn’t necessarily tell us the number of births women eventually have The fertility rate is commonly confused with the eventual number of births per woman. This can result in misinterpreting the impact of policies and trends over time.

A striking trend, but also important to remember that these changes in period fertility rates often look overdramatic when childbearing is shifting to older ages, which is especially the case in Latin America where adolescent births have been traditionally high. ourworldindata.org/total-fertil...

"Our study found that preference for two children was not significantly stronger than preference for zero, one, or three children when competing work, financial, and family demands were taken into account"

Prospective Students | Graduate Group in Demography

The Graduate Group in Demography at the University of Pennsylvania is now accepting applications for its PhD program in Demography. We look forward to recruiting a strong and diverse cohort for Fall 2026!

➡️ Applications are due December 15, 2025 ⬅️

Learn More:

When “Stuff Happens” After Vaccination How scientists separate coincidence from true side effects

A must read from @drjenndowd.bsky.social

When “Stuff Happens” After Vaccination open.substack.com/pub/jenndowd...

Great point!

Low Birth Rates Are Here To Stay | Opinion Individuals and families need to be supported by a strong social safety net that includes paid leave and a robust child care infrastructure. There are no quick fixes.

"Fundamentally, having a child is making a decision about the future."

Great piece by @karenguzzo.bsky.social #demography #birthrates
www.newsweek.com/low-birth-ra...

Thank you for the kind words! I wish it weren’t so necessary to continue to make this point, but seems like it will be relevant for the foreseeable future….

Wen Su wins the Charles Price Prize in Demography Wen Su, Postdoctoral Researcher at the Leverhulme Centre for Demographic Science recently won the Charles Price Prize in Demography.

🎉 Big congrats to @wensu221.bsky.social Su, Postdoc at LCDS, for winning the Charles Price Prize in #Demography! 🏆 His work bridges national & subpopulation #mortality to reveal hidden patterns in health outcomes. A true star demographer in the making! 🌟

www.demography.ox.ac.uk/news/wen-su-...

If you missed @phbocquier.bsky.social's presentation at the Formal Demography working group last week, you can now watch the recording! ⏬

Religion generally declines between generations in three steps: People participate in worship services less often. The importance of religion declines in their personal lives. Belonging to religion becomes less common. They call this the Participation-Importance-Belonging (P-I-B) sequence. In this sequence, generations first shed aspects of religion that require more time and resources. People are slower to shed religious identity, which is not necessarily as burdensome. In the early stage of secular transition, generations differ primarily in their religious participation. In some countries that remain highly religious today, recent surveys show that each country’s share of adults under age 40 who frequently attend religious services has dropped below the share of older adults who do so. Many African countries are currently in this early stage. For example, in Senegal, 78% of older adults attend worship services weekly, but younger adults are 14 percentage points less likely to do so. Yet almost all adults in Senegal – both young and old – still identify as Muslims and consider religion very important in their lives.

In the medium stage of secular transition, generations differ in their religious participation, importance and belonging. In countries that are moderately religious, all three steps in the P-I-B sequence are visible in recent surveys. Adults under 40 attend services less frequently than their elders, are less likely to say religion is important in their lives and are less likely to identify with any religion. This is the case currently in the U.S., along with many other countries in the Americas and Asia.

In the late stage of secular transition, generations differ primarily in religious belonging. The authors contend that this is because the first two steps have been completed. The shares of older adults who attend services and who consider religion important in their lives have already dropped to low levels, similar to those of younger adults. In the least religious countries today, the main difference between age groups is that younger adults are less likely to identify with any religion. Many countries in Europe have reached this stage. For example, in Denmark, 79% of older adults remain religiously affiliated, but adults under 40 are 26 points less likely to say they belong to any religion. Attendance at religious services and self-assessments of the importance of religion are low among people of all ages.

A secular transition is happening in countries around the world. Detailed explanation🧪 www.nature.com/articles/s41....
Many Muslim-majority countries, Hindu-majority India in early stage. Countries with large Buddhist & Christian populations in later stages.
Blog: www.pewresearch.org/short-reads/...