June/July 2025: Thimerosal in multidose vaccine vials: Then and now

Dr. Paul Offit talks about the history of thimerosal, an ethylmercury-containing preservative used in vaccines between 1930 and 2000 to prevent bacterial and fungal contamination. Unfounded concerns about thimerosal and autism led pharmaceutical companies to move from multidose vaccine vials to single dose vials. Several studies found no link between thimerosal and autism, and despite its removal from childhood vaccines by 2001, rates of autism have continued to increase. 

Thimerosal resources

• Vaccine Ingredients: Thimerosal
• Thimerosal: What you should know English | Spanish
• Is there mercury in vaccines? (video)

Resources related to topics from the June ACIP meeting

• MMR and chickenpox vaccines: Together or separate? (video)
• Why Do Newborns Get the Hepatitis B Vaccine? (video)
• Hepatitis B: What you should know (Q&A): English | Spanish | Japanese
• Hepatitis B (infographic)
• How Does Hepatitis B Combat the Immune System?
• Vaccine Safety and Your Family: Separating Fact from Fiction (booklet): English | Spanish
• Science Behind the Vaccine Schedule
• Immune System and Vaccines
• Vaccine Safety References (See “Too many vaccines, too soon” for studies looking at the overall schedule.)

COVID-19 resources

June 2025: Understanding recent announcements about COVID-19 vaccines

Dr. Paul Offit discusses recent announcements related to COVID-19 vaccines, including a proposed framework for thinking about COVID-19 vaccines and an announcement about who will be able to get COVID-19 vaccines. Dr. Offit also describes how these announcements were aberrations from the usual approach to vaccine review, licensure and recommendations and how that has caused confusion and questions.

For more information related to COVID-19 and the vaccines, see these resources:

General information

• COVIDVaccineAnswers.org
• Vaccines and Diseases: COVID-19
• COVID-19: What you should know: English | Spanish | Japanese
• COVID-19: The Disease vs the Vaccine – infographic
• COVID-19 Vaccines: What’s in the Vial? – infographic  

Related to long-term and immune system effects

• Long-term Side Effects of COVID-19 Vaccine? What We Know. (article)
• What Stops Body from Continuing to Produce the COVID-19 Spike Protein after Getting an mRNA Vaccine? (video)
• What Are the Long-term Side Effects of COVID-19 Vaccine? (video)
• Do COVID-19 Vaccines Disrupt the Immune Response? (video)
• How COVID-19 mRNA Vaccines Work (animation)

Measles resources

May 2025: Measles — How did we get here, and how bad is this?

Dr. Paul Offit talks about the growing measles outbreak in the United States, explaining that the number of cases is higher than CDC reports, and how we know that. He says that underfunding and misinformation have hindered the response to the current epidemic and that vaccination is remarkably safe.

As of June 24, 2025: 1,227 cases of measles have been confirmed in 37 locations throughout the U.S.  

For more information related to measles, see these resources:

• Measles, Mumps and Rubella (MMR): The Diseases and Vaccines (webpage)
• Measles, Mumps & Rubella (infographic): PDF (English | Spanish) | PNG
• Measles: What You Should Know (Q&A): English | Spanish
• Rash Information, includes measles image and information (webpage)
• Parents PACK Personal Stories – Measles (webpage)
• Measles infections, outbreaks & vaccines playlist (videos)
  • Measles: symptoms, spread & SSPE
  • Why Are We Seeing Measles Outbreaks?
  • March 2025 - Measles outbreaks: At the intersection of vaccines and religion
  • 3 lessons from current TX measles outbreak: Higher cases, low vaccination & too much vitamin A
  • Is Vitamin A Effective for Treating or Preventing Measles?
  • Vaccine Expert Reacts: RFK Jr. Falsely Claims Measles Vax Causes Deaths 'Every Year', MedPage Today
  • ATS Breathe Easy - Vaccine Hesitancy and the Fear of a Measles Outbreak, American Thoracic Society
  • This Is How Easy It Is To Spread Measles, National Foundation for Infectious Diseases
  • 5 Things You Need to Know About Measles In 30 Seconds, National Foundation for Infectious Diseases
  • Do people need a measles vaccine booster during an outbreak?
  • MMR and chickenpox vaccines: Together or separate?
  • Attenuation: How Scientists Make Live Vaccines
  • Wouldn’t it be better for my child to get diseases naturally?

Last updated: June 26, 2025