ImmunizeDelaware

04/15/2026

It's Wednesday! Have an IZ Express, on us!

Keep updated on immunization news. Read IZ Express Issue Number 1869.

04/13/2026

04/13/2026

A completed CDC report showing the COVID vaccine reduced ER visits and hospitalizations in healthy adults by about HALF last winter was just blocked from publication by the acting CDC director. It had cleared internal scientific review and was scheduled for March 19 in the MMWR (the CDC’s primary vehicle for publishing public health data and findings). The stated reason was concerns about the methodology. So let’s talk about it…

The methodology in question is called test-negative design, and there’s a very good reason why it became the standard for measuring vaccine effectiveness over the past two decades.

Randomized controlled trials sound more rigorous on paper, but for an already-recommended vaccine they’re both logistically impractical and ethically complicated — you can’t easily ask people to accept a placebo for something they’re already advised to get.

Test-negative design works differently: you look at people already sick enough to seek care, test them, and compare vaccination rates between those who test positive and those who don’t. Starting at the point of care controls for a major confounding problem (because people who seek medical attention are systematically different from those who don’t). Like all study designs, it has limitations — it only captures people seeking care, not the broader population, and selection bias can enter if testing isn’t applied consistently. Researchers know this, account for it in their analyses, and use it to inform how findings are interpreted.

The flu vaccine effectiveness report published in the same MMWR one week earlier used this exact method. No concerns were raised. Why the double standard? 🤔

This leads us to believe that the demand for a different methodology isn’t coming from a place of genuine scientific concern; we stopped doing placebo-controlled trials for recommended vaccines largely for ethical reasons. You don’t withhold a recommended intervention from half your study population to satisfy a methodological preference. That’s NOT a higher standard. The people raising these objections know that, or at least they should.

04/13/2026

Happy Monday! Have a Week in Review!https://immunizedelaware.org/wp-content/uploads/April-13.pdf

04/08/2026

Happy Wednesday!

Keep updated on immunization news. Read IZ Express Issue Number 1868.

04/06/2026

04/06/2026

Happy Monday, y'all! Hope everyone had a nice weekend!

https://immunizedelaware.org/wp-content/uploads/April-6.pdf

04/01/2026

It's Wednesday - how about an IZ Express?

Keep updated on immunization news. Read IZ Express Issue Number 1867.

04/01/2026

More info about the new COVID variant, "cicada"

03/30/2026

Happy Monday, Delaware!https://immunizedelaware.org/wp-content/uploads/March-30.pdf

03/25/2026

It's Wednesday!

Keep updated on immunization news. Read IZ Express Issue Number 1866.