This TWiV clinical update with Dr. Daniel Griffin and Vincent Racaniello addresses critical public health issues, beginning with a strong rebuke of misinformation surrounding vaccine safety. They highlight the enduring misrepresentation of thimerosal in vaccines and critique the decision by CBER director Vinay Prasad to overrule expert recommendations for COVID-19 vaccine administration, particularly concerning pregnant individuals and general access, which is seen as undermining scientific consensus.
The episode then transitions to epidemiological updates, detailing the concerning rise in measles cases in the US and the Americas, leading to international travel restrictions for US citizens. Dr. Griffin reviews the devastating 2024-2025 flu season, noting a record number of pediatric deaths and emphasizing the effectiveness of maternal and childhood vaccination. COVID-19 data includes wastewater surveillance trends and an independent assessment supporting the zoonotic origin of SARS-CoV-2 over lab-leak theories. Discussions on COVID-19 vaccine effectiveness, the link between COVID-19 and severe renal outcomes (AKI), and long COVID manifestations like cognitive changes and new-onset Type 1 diabetes in children underscore the ongoing impact of the virus. The episode concludes with a call to support science communication and addresses listener questions regarding vaccine schedules and access to treatments like Paxlovid.
TWiV 1232: Clinical update with Dr. Daniel Griffin β Key Insights
0:00 Introduction & Thimerosal Misinformation: Dr. Daniel Griffin and Vincent Racaniello begin by criticizing the spread of misinformation, particularly regarding thimerosal in vaccines.
3:19 Thimerosal Safety and Removal: Thimerosal, an ethyl mercury compound, was used as a vaccine preservative but was largely removed from US childhood vaccines by 2001 as a precautionary measure, not due to evidence of harm. MMR, varicella, polio, and pneumococcal conjugate vaccines have never contained thimerosal. The WHO and CDC confirm no evidence of harm from thimerosal.
9:51 CBER Director Overrides Scientists: Dr. Griffin expresses shock and concern over the FDA's CBER Director, Vinay Prasad, overruling staff experts' recommendations for broad use of Novavax and new Moderna mRNA COVID vaccines. This is described as a "dark time in public health" and an advancement of personal agendas over science.
13:39 Myocarditis Risk: COVID-19 infection poses a 7-16 times higher risk of myocarditis than vaccination. Spacing out vaccine doses has further reduced post-vaccination myocarditis.
15:40 Restricted Vaccine Access: Due to the CBER Director's decision, many individuals, including healthcare workers and those under 65, may need to obtain Novavax or the new Moderna COVID vaccine "off-label" despite their safety and efficacy.
18:25 Measles Outbreak in US: The US is experiencing a significant measles resurgence, with 1,227 confirmed cases across 37 jurisdictions as of June 24th, 2025, nearing records since its 2000 elimination. This has led to US travelers requiring proof of measles vaccination for entry to countries like Honduras.
22:41 Record Pediatric Flu Deaths: The 2024-2025 flu season saw 253 flu-associated pediatric deaths, the highest number in any non-pandemic season since 2004. 90% of these children were unvaccinated, and most were otherwise healthy.
23:55 Maternal Flu Vaccination Benefits: Flu vaccination during pregnancy significantly reduces infant influenza risk in the first six months of life, with third-trimester vaccination providing a 59.3% reduction.
27:01 Universal Flu Vaccine Recommendation: Unlike COVID-19 vaccines, flu vaccines are universally recommended for everyone six months of age and older, including pregnant individuals, underscoring the inconsistency in public health messaging and access.
30:51 WHO Assessment on SARS-CoV-2 Origins: An independent WHO assessment reviewed four hypotheses for SARS-CoV-2 origins (natural zoonotic, accidental lab leak, cold chain, deliberate manipulation). The most available scientific evidence supports natural zoonotic transmission, with zero data supporting lab leak theories.
33:40 Evolving COVID-19 Variants: Variants like NB.1.8.1 and XFG are outcompeting others, though all remain within the JN.1 lineage. CDC data precision for variants is noted as low due to reduced sequencing.
37:28 COVID-19 Vaccine Effectiveness: Recent JAMA data (2023-2024) shows COVID-19 vaccine effectiveness against emergency department/urgent care encounters (24%), hospitalizations (29%), and critical illness (48%), with a second dose benefiting high-risk individuals.
39:50 COVID-19 and Kidney Injury: A study found unvaccinated COVID-19 patients had significantly higher rates of acute kidney injury requiring renal replacement therapy and a fivefold increase in both hospital and long-term mortality.
43:04 Long COVID & Cognitive/Diabetes Impacts: Long COVID clinics face months-long waiting lists. Studies link COVID-19 infection to faster cognitive decline (memory, executive function) and a significantly increased risk (up to sevenfold) of new-onset Type 1 diabetes in children and young people.
49:15 Paxlovid Access Issues: Medicare Part D beneficiaries are reportedly facing thousands of dollars in out-of-pocket costs for Paxlovid, despite being well-insured. Dr. Griffin provides a link to a Pfizer patient support program to address this.
51:12 Critique of Biased Research: A preprint by Florida Surgeon General Joseph Ladapo, suggesting higher mortality after certain COVID-19 vaccines, is strongly criticized as biased, ideologically driven, and methodologically flawed due to confounding issues.
54:05 Anti-Science Policies Spreading: Anti-science policies, similar to those in the US, are impacting Canada, with Alberta's provincial government making COVID vaccines non-free for many and spreading misinformation.
56:49 Measles Vaccine Cadence: The CDC recommends two doses of measles vaccine at least four weeks apart; a listener who received two doses three days apart needs a proper second shot.