Pfizer vs. Moderna in Florida: Higher Mortality After Pfizer? (But Correlation Isn't Causation!)

Overview

Paper Summary › Explain Like I'm Five › Conflicts of Interest › Identified Limitations › Rating Explanation › Good to know › Topic Hierarchy › File Information ›

Paper Summary

Paperzilla title

This observational study of Florida adults found a correlation between receiving the Pfizer (BNT162b2) COVID-19 vaccine and a higher risk of 12-month all-cause mortality compared to receiving the Moderna (mRNA-1273) vaccine. However, the study's design cannot determine causality and residual confounding cannot be ruled out despite extensive matching.

Explain Like I'm Five

Scientists found that in Florida, adults who got the Pfizer COVID shot seemed to have a slightly higher chance of dying in the next year than those who got the Moderna shot. But they're not sure if the shot caused it, or if something else was at play.

Possible Conflicts of Interest

Joseph A. Ladapo, MD, PhD, is supported by the Florida Department of Health and serves as State Surgeon General. Retsef Levi, PhD has a financial relationship with Bluebell Foundation/Chicago Community Trust.

Identified Limitations

Matching criteria limitations

The matching criteria, while extensive, did not include potentially important characteristics like pre-existing health conditions, which could confound the analysis and introduce bias.

Reduced sample size due to matching

While the study boasts a large sample size, the matching process significantly reduced the analyzed population, potentially limiting the generalizability of the findings to the broader population.

Potential for misclassification bias

The study relies on death certificates for outcome classification, which can be prone to errors and introduce misclassification bias, although this bias is unlikely to be differential between vaccine groups.

Negative control selection

The selection of negative controls was complex due to the unknown nature of nonspecific vaccine effects. While suicide/homicide and prior SARS-CoV-2 infection were selected, there may be other relevant negative controls that could strengthen the study's conclusions.

Correlation does not equal causation

The study does not establish causality. While it shows an association between BNT162b2 and increased mortality, further research is needed to determine if the vaccine directly causes this effect or if other factors are involved.

Rating Explanation

This observational study presents intriguing findings about higher all-cause mortality among BNT162b2 recipients compared to mRNA-1273 recipients. The extensive matching and large sample size are strengths, but the lack of detailed comorbidity data, potential for residual confounding, and inability to establish causality limit the strength of the conclusions. The authors acknowledge these limitations and the declared conflicts of interest are noted, placing this as an average study with suggestive but not definitive findings.

Good to know

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Topic Hierarchy

Domain: Health Sciences

Field: Medicine

Subfield: Epidemiology

File Information

Original Title: Twelve-Month All-Cause Mortality after Initial COVID-19 Vaccination with Pfizer-BioNTech or mRNA-1273 among Adults Living in Florida

Uploaded: July 20, 2025 at 06:21 AM

Privacy: Public