Shot of Prevention

By Alison Singer
President, Autism Science Foundation

There are two main questions that parents of children with autism have been asking us about H1N1 virus and H1N1 vaccine. The first is whether our children are at higher risk from complications from H1N1 and thus need to be given prioritization with regard to vaccination. Much of this concern stems from the fact that because of communication challenges, kids with a developmental disability often can’t tell us when they are sick. Thus, treatment of an H1N1 infection might be delayed.

The second question on people’s minds is whether the vaccines will contain thimerosal. According to the CDC, the 2009 novel H1N1 influenza vaccines that FDA is licensing will be manufactured in several formulations. Some will come in multi-dose vials and will contain thimerosal as a preservative. Parents can be assured that the most recent and rigorous scientific research does not support the hypothesis that thimerosal-containing vaccines are harmful.

Should kids with autism be given priority in vaccination?

The September 3, 2009 issue of CDC’s Morbidity and Mortality Weekly Report (MMWR) reported that of the 36 children with a confirmed 2009 H1N1 infection who died between April and early August 2009, twenty-four had chronic medical conditions that have been recognized to increase the risk of complications from seasonal influenza.  In particular, many children had neurodevelopmental conditions, such as cerebral palsy, epilepsy, and developmental delay. (http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5834a1.htm).

One of the authors of this report, Dr. Georgina Peacock of the CDC’s National Center on Birth Defects and Developmental Disabilities, says that the majority of these children had neurodevelopmental disabilities that left them at risk for pulmonary compromise — this would include children that may have trouble clearing secretions, protecting their airway or difficulties coughing. In addition, almost all of the children had more than one neurodevelopmental problem, such as cerebral palsy and epilepsy.  Thus there is not a specific priority vaccination group for individuals with developmental delay or other neurodevelopmental conditions.

Dr. Peacock added that there has not been any prioritization for the 2009 H1N1 vaccine within the priority groups and stressed that all children and young adults should be vaccinated for 2009  H1N1 influenza  when it becomes available. In addition, children should be up to date on their pneumococcal vaccine–this would include the 7-valent vaccine (Prevnar) for children under 2 (which is part of routine vaccinations)  and  additionally  the 23-valent vaccine  (Pneumovax)  for children greater than 2 with a high-risk medical condition.  This will help to protect against some types of pneumonia, which a complication that can develop after influenza infection.

If children who are in one of the higher risk groups develop flu-like symptoms, including a fever, sore throat and/or cough, parents should contact their child’s doctor or seek medical attention.  Parents should talk to a doctor early if worried about their child’s illness.  There are anti-viral medications that can be helpful in treating influenza especially when started early. In addition, although not in a priority group, parents of children with developmental disabilities are urged to get vaccinated as soon as vaccine becomes available to the general public.

What About Thimerosal?

According to the CDC, the 2009 novel H1N1 influenza vaccines that FDA is licensing will be manufactured in several formulations. Some will come in multi-dose vials and will contain thimerosal as a preservative. Multi-dose vials of seasonal influenza vaccine also contain thimerosal to prevent potential contamination after the vial is opened.

Some vaccine manufacturers will be producing novel H1N1 influenza vaccine in single-dose units, which will not require the use of thimerosal as a preservative. In addition, the live-attenuated version of the vaccine, which is administered intranasally (through the nose), is produced in single-units and will not contain thimerosal.

Since 2001, no new vaccine licensed by FDA for use in children has contained thimerosal as a preservative, and all vaccines routinely recommended by CDC for children under six years of age have been thimerosal-free, or contain only trace amounts, except for multi-dose formulations of influenza vaccine. This was done as a precautionary step and not because there was evidence confirming that thimerosal-containing vaccines were causing health problems. The most recent and rigorous scientific research does not support the hypothesis that thimerosal-containing vaccines are harmful.

Thimerosal is an important preservative that protects vaccines against potential microbial contamination, which may occur in opened multi-dose vials of vaccine. Such contamination could cause serious illness or death. Since seasonal influenza vaccine is produced in large quantities for annual immunization campaigns, some of the vaccine is produced in multi-dose vials, and contains thimerosal to safeguard against possible contamination of the vial once it is opened.

Three leading federal agencies (CDC, FDA, and NIH) have reviewed the published research on thimerosal and found it to be a safe product to use in vaccines. Three independent organizations (The National Academy of Sciences’ Institute of Medicine (IOM), the Advisory Committee on Immunization Practices (ACIP), and the American Academy of Pediatrics (AAP)) reviewed the published research and also found thimerosal to be a safe product to use in vaccines.

Nonetheless, the presence of the preservative thimerosal in vaccines and suggestions of a relationship to autism has raised concerns. Since 2001, no new vaccine licensed by FDA for use in children has contained thimerosal as a preservative,  and all vaccines routinely recommended by CDC for children under six years of age have been thimerosal-free, or contain only trace amounts, except for some formulations of influenza vaccine, and yet, we have not seen reductions in the numbers of children diagnosed with autism, indicating that the cause of autism is not related to thimerosal.

H1N1 influenza vaccine is expected to have a similar safety profile to seasonal flu vaccines, which have a very good safety track record. Data from novel H1N1 trials among children are not available yet.

According to current federal plans, only unadjuvanted vaccines will be used in the United States during the 2009 flu season. This includes all of the 2009 H1N1 and seasonal influenza vaccines that will be available for children and adults in both the injectable and nasal spray formulations. Original plans for novel H1N1 vaccine referenced possible use of the adjuvant squalene, but this is no longer necessary given that testing showed that single dose H1N1 vaccination produced a stronger than expected immune response, thus reducing the need to “stretch” the amount of antigen available to the public by adding adjuvant to the vaccines.