evidence: A new study suggests there may be a link between aluminum used in vaccines that are given to young children in the first two years of life and the risk of developing asthma before age 5. The findings are preliminary and both the authors and others who have studied the data urge caution in the interpretation of the results. [...] Aluminum is used in a number of vaccines as an adjuvant — a way to boost the immune response the product triggers. The practice has been used for decades. Vaccines that young children receive that contain aluminum include: diphtheria, tetanus, and acellular pertussis; hepatitis B; some formulations of Haemophilus influenzae type B or Hib vaccine; and pneumococcal conjugate vaccines. Covid-19 vaccines and flu shots do not contain aluminum, the CDC said in its statement.