Welcome to the week.

It’s 2026 and measles is back in a way it hasn’t been in over three decades. And everywhere we’re seeing a resurgence, the story is really about reach: whether the vaccine, the funding, and the trust to deliver it actually get to every community.

Globally, that gap is largely due to funding and distribution, where places hit hardest are concentrated in countries facing conflict or instability.

At home, it looks a bit different. Pennsylvania and Mississippi aren’t short on vaccine supply, they’re short on coverage in specific pockets.

But whatever the reason, the lesson is that measles doesn’t need most people to be unvaccinated, it just needs enough gaps.

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Have a great week,

— Willow

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Pennsylvania is in the middle of the largest measles outbreak in decades, with 767 confirmed cases across 38 counties. Only 4 of the confirmed cases (under 1%) were in people who’d had both doses of the MMR vaccine. (The Atlantic, Pennsylvania Department of Health)

Meanwhile, in Mississippi, eight counties have already dropped below the 95% vaccination rate needed for herd immunity, with the steepest declines following a 2023 federal ruling that forced the state to allow religious exemptions (Mississippi Free Press).

Globally, coverage has plateaued well below where it needs to be, with just 76% with the second dose in 2024, well below the 95% threshold needed to stop the virus from spreading. That gap left roughly 360,000 confirmed cases worldwide in 2024 (the highest since 2019).

Our World in Data estimates measles vaccination alone has saved 94 million lives since 1974, more than any other childhood vaccine currently in use.

When the measles vaccine arrived in 1963, cases fell by more than 90% within 5 years, and by the late 1990s, the US was down to single and double digits a year.

The country eliminated measles in 2000, meaning there was no continuous domestic transmission for 12 straight months, but 2026 is testing that status with 3,471 confirmed cases as of September 17th, the worst year since 1991.

Measles isn’t evolving or getting harder to stop. The vaccine is still very effective — about 97% effective after two doses.

We can choose to look at that through a hopeful lens, because this problem isn’t waiting on new tech or decades of infrastructure development. It’s a problem of reach, and reach is something that can move fast in both directions, for better or worse, as Pennsylvania’s own emergency vaccination push this summer shows.

It’s the same idea at the global scale. Essential medicines and vaccines don’t help anyone sitting in a warehouse. Let’s do the work to get them the rest of the way.

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Last week, we asked: Roughly how many people worldwide currently lack access to safely managed drinking water?

🟨⬜️⬜️⬜️⬜️⬜️ 1 in 20 people (13%)
🟨🟨🟨⬜️⬜️⬜️ 1 in 10 people (26%)
🟩🟩🟩🟩🟩🟩 1 in 4 people (55%)
⬜️⬜️⬜️⬜️⬜️⬜️ 1 in 2 people (6%)

The correct answer: One in four. Over two billion people globally still lack access to safely managed drinking water. Most of you got it right!

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