COVID-19 Vaccine mRNA Distribution Extends Beyond Injection Site, Studies Indicate

Recent scientific reviews challenge the initial understanding that mRNA from COVID-19 vaccines remains primarily localized at the injection site and draining lymph nodes. While these areas are indeed primary sites of concentration, accumulating evidence from both human and animal studies suggests a broader, albeit limited, systemic distribution of vaccine components and their encoded proteins. This evolving scientific picture provides crucial context for public discussions surrounding vaccine safety and efficacy.

Dr. Jake Scott, MD, acknowledged the public confusion regarding this topic, stating in a recent tweet, "> The mRNA from COVID vaccines primarily stays local at the injection site and its draining lymph nodes. I understand why this has become controversial and confusing. There's a lot of scary information out there. I'll try to clarify a few things." His statement reflects a common initial understanding, but research has since revealed more intricate biodistribution patterns.

According to a comprehensive review published in Vaccines in 2024, "a lot of evidence has accumulated suggesting that LNPs, mRNA, and protein products of mRNA vaccines are detectable in almost all organs and tissues including the brain, heart, lungs, testes, ovaries, and skin." This review highlights that vaccine mRNA can be found in blood plasma within hours of vaccination and persist for up to 15-28 days. The encoded spike protein has been detected in blood plasma for even longer, with some studies finding it up to 187 days post-vaccination.

Further human studies cited in the review indicate the presence of vaccine mRNA in axillary lymph nodes up to 60 days after vaccination. Trace amounts of vaccine mRNA have also been detected in breast milk for up to 48 hours post-vaccination in some lactating individuals, though typically in fragmented and translationally inactive forms. While mRNA has been found in heart tissue in a small number of autopsy cases, studies suggest that vaccine mRNA is generally unable to cross the blood-placental barrier.

The scientific community continues to investigate the full biodistribution and long-term implications of mRNA vaccines. These findings underscore the dynamic nature of scientific understanding and the ongoing commitment to transparently assess vaccine characteristics, ensuring public health recommendations are based on the most current and comprehensive data available.