As the influenza vaccine market expanded, so did recommendations for use by the CDC’s Advisory Committee on Immunization Practices (ACIP).
In 1984, the CDC recommended annual flu shots for high risk individuals, which included adults over the age of 65; any person with a chronic illness or a metabolic disorder; persons living in nursing homes or other long-term care facilities; and health care personnel. At that time, pregnancy was not considered to be a high-risk factor for severe illness or complications from influenza. The 1984 ACIP committee stated, Pregnancy has not been demonstrated to be a risk factor for severe influenza infection, except in the largest pandemics of 1918-1919 and 1957-1958.
However, in 1997, the CDC updated influenza vaccine recommendations to include pregnant women in their second or third trimester. This recommendation was considered an off-label use of the vaccine because the FDA had not licensed influenza vaccine for use by pregnant women. The CDC’s recommendation in 1997 was based on information contained in a small number of documents from the 1918-1919 and 1957-1958 influenza pandemics, and a few case reports and small studies which reported an increase in influenza-related hospitalizations in pregnant women.
Between 1999 and 2010, the ACIP annual recommendations for the seasonal flu vaccine quickly expanded to include more and more target populations. Infants and children, aged 6 months to 23 months, were added in 2004. The presence of thimerosal, a mercury-containing preservative present in all multi-vial flu vaccine vials, was discussed by ACIP due to a 1999 recommendation which called for its removal from all vaccines routinely administered to children. In 2004, however, the CDC stated that, the benefits of influenza vaccination outweigh the theoretical risk, if any, for thimerosal exposure through vaccination,
and there was no recommendation made for infants, children or even pregnant women to receive a thimerosal-free influenza vaccine.
By 2010, ACIP voted to recommend that every person six months and older, including pregnant women at any stage of pregnancy, receive an annual flu shot. The only contraindications were for persons with a history of hypersensitivity or anaphylaxis to eggs or any other influenza vaccine ingredient, or history of Guillain-Barre Syndrome (GBS).
In 2011, however, the CDC began recommending that individuals who had previously developed hives following exposure to eggs receive the influenza vaccine and by 2016, egg allergies were no longer considered a contraindication to receiving a flu vaccine.
Currently a severe allergy to a vaccine component or history of a life-threatening allergic reaction to a previous flu shot are the only CDC approved official contraindications (medical reasons for not getting vaccinated) to receiving influenza vaccine. A history of GBS within 6 weeks of a previous flu vaccine, a severe egg allergy (i.e. respiratory distress, recurrent vomiting, angioedema, lightheadedness, treatment with epinephrine) or moderate or severe acute illness with or without a fever,
are now only considered precautions to vaccination. According to the CDC, individuals with a history of severe egg allergies can receive any flu vaccine that is indicated for their age without any additional safety measures other than those recommended for the receipt of any vaccine.
