Key Vaccine Topics Explained

A selection of curated resources organized by topic.

  • The routine birth dose of hepatitis B vaccine is safe and has prevented thousands of children a year from getting chronic hepatitis B, which often results in cirrhosis and liver cancer. Just testing mothers for hepatitis B is not enough. The December 2025 change in ACIP recommendations to remove the birth dose went against the advice of nearly all experts, including the American Academy of Pediatrics (AAP), and takes us back 40 years. It will make vaccine less accessible and confuse parents, delaying and reducing immunizations. The result will be more preventable life-long infections, liver cancer and cirrhosis. For this reason the AAP and other experts recommend continuing the prior recommendation of a universal birth dose. For additional information see:

  • Combination vaccines reduce the number of shots children need to get, and the number and costs of visits to doctors and other providers, while increasing the diseases children are protected again. The combinations are fully studied and vaccines must be approved as they are used by FDA. Repeated studies, including during use over many years in millions of children, show no meaningful harms and significant benefits from combination vaccines, including higher immunization and lower disease rates. There is no reason to break combination vaccines down into their individual components and doing so would require new studies, expensive reformulation of existing vaccines, and result in increased shots, discomfort and health care visits and costs.

  • The U.S. childhood vaccine schedule has been based on careful consideration of the risks and harms of the prevented diseases, and benefits of the vaccine in preventing those diseases, in the US population. There is no evidence that the human immune system cannot handle responding to more than one vaccine at once or over time, and it normally responds to multiple bacteria and viruses as children are exposed to them every single. This is how the immune system learns and protects us against future threats. Recently it has been suggested by political appointees in the Department of Health and Human Services that the US, instead of following a schedule like that of most similar high income countries such as in Canada and Europe, should follow Denmark’s vaccine schedule and recommend significantly fewer vaccines. If that was done, access to vaccines and protection against numerous infections in the US would be eroded, meaning more illness and hospitalizations from meningitis, hepatitis A and B, rotavirus, and influenza, among others. For additional information, see:

  • Adjuvants (from the Latin word adjuvare, and meaning helping towards) are substances added to some vaccines, only when needed, to help strengthen the body’s immune response to prepare for and effectively protect against an infection. Aluminum salts are the most commonly used adjuvants and have been safely used for over a hundred years. Aluminum makes up ~ 1/10th of the earth’s crust and food in our diets is the main source of aluminum in or bodies, and is rapidly excreted by our kidneys. The amounts of aluminum present in all vaccines given to infants is less than received from breast milk. Multiple studies, including one of all Danish children followed over 24 years, show no adverse effects on health (including allergies, autism, autoimmune disease etc.) associated with aluminum exposure from vaccines. For additional information see:

  • There is an increased risk of serious complications, including hospitalization and death, from COVID-19 infection when it occurs during pregnancy, as has been recognized by CDC and FDA. In addition, COVID-19 infection in pregnancy has been associated with preterm delivery and neonatal death. COVID vaccines have been safe and effective in pregnancy and also generate antibodies that are passed from the mother to help protect the infant in its first few months of life. As a result, physicians as well as CDC and its Advisory Committee on Immunization Practices (ACIP) have strongly recommended COVID-19 boosters for pregnant women. However, after RFK Jr. fired all ACIP members in 2025 and replaced them with hand picked individuals, , as of 9/2025 CDC has not had a clear recommendation on pregnancy and instead has stated that vaccination should be determined by “individual decision-making”. There are no data to support removal of the prior recommendation that pregnant women receive COVID boosters and major professional societies, including of obstetricians and gynecologists, family physicians and infectious diseases specialists, continue to recommend COVID vaccination during pregnancy to protect the mother and newborn.

  • Multiple expert reviews of the scientific evidence have shown no association of vaccinations (including MMR) or of past or present vaccine ingredients with the development of autism, or with increased rates of diagnosed autism in recent decades.

  • Following the changes in ACIP, and its adoption during 2025 of controversial decisions not supported by the medical and public health community, such as the lack of recommendation of COVID vaccine for pregnant women, independent scientific and medical experts, including professional societies and others have independently reviewed updated data and provided recommendations for treating physicians and other providers.