Does the Level of Protection Against the Hepatitis B Virus Differ Based on the Way in Which the Vaccine is Given (for example, injected into a muscle or injected under the skin)?
Just like the general population, people with hemophilia and other bleeding disorders require vaccinations to prevent certain diseases, such as Hepatitis B infection, an infection that targets the liver. Vaccinations, or shots, may be given by injection under the skin or into a muscle depending on the particular vaccine. Prior research has shown that injecting the hepatitis A vaccine under the skin (as opposed to into the muscle as usually recommended) is effective and tends to cause fewer problems at the site of injection in children with bleeding disorders. However, not all vaccines have been tested this way and little is known about whether the way vaccines are given (known as the route of administration) makes a difference in the body’s ability to make specific antibodies designed to protect itself against disease and infection. Despite the fact that children with bleeding disorders, especially those with severe disease, are at risk for muscle bleeds, infants are routinely given Hepatitis B vaccine into a muscle. Therefore, the safety and effectiveness of giving infants with bleeding disorders the hepatitis B vaccine under the skin needed to be studied.
About this Study
CDC’s Division of Blood Disorders and Hemophilia Treatment Center investigators conducted a study among children less than 2 years of age who were enrolled in the Universal Data Collection project to compare whether the route of administration (giving participants the Hepatitis B vaccine under the skin versus into the muscle) would or would not cause them to make antibodies that protect them from getting the Hepatitis B virus. Researchers looked at Hepatitis B virus surface antibody levels among patients enrolled in the UDC database who had received three doses of the Hepatitis B vaccine by only one route (either under the skin or into the muscle). This study, published in the journal Haemophilia used data collected by medical care providers on infants immunized between July 2003 and September 2011. We invite you to read the abstract hereExternal.
An antibody is a protein produced by the body’s immune system when it detects harmful substances such as bacteria, fungi, parasites, viruses and chemicals. Antibodies protect the person from the disease or infection.
Hepatitis B surface antibody (anti-HBs) level is measured to determine if vaccination is needed, or to determine if protection from infection has been achieved following vaccination.
Main Findings from this Study
- Eighty-five of 92 participants (92.4%) who received the Hepatitis B vaccine injected under the skin developed adequate amounts of the Hepatitis B surface antigen (a positive antibody titer) compared to 101 out of 114 participants (88.6%) who received the vaccine injected into the muscle. Titers are blood tests that check how well you produced antibodies (immune status) to vaccinations or to the actual diseases in the past.
- The level of immunity or protection provided by the Hepatitis B Vaccine was similar regardless of the route of administration, although the titers were tested long after the vaccination in some cases, which may have affected the results.
- Hepatitis B vaccination given by injection under the skin appears to be equally effective as injection into the muscle in protecting individuals with bleeding disorders from Hepatitis B infection.
- Side effects such as muscle bleeding seemed to occur less often among those getting the vaccination under the skin (versus into the muscle), but the study wasn’t designed specifically to measure all possible side effects of vaccination.
Critical Gaps & Future Directions
The results of this analysis suggest that giving the hepatitis B vaccine under the skin to a person with a bleeding disorder results in adequate protection from the disease while decreasing the risk of a serious muscle bleed. A formal study to confirm these findings is being planned to collect more data about antibody levels and side effects resulting from these vaccination routes.
For more information on the UDC Project, please visit our UDC webpages.
For more information about Hemophilia, please visit our Hemophilia webpages.
For more information about Hepatitis B, please visit CDC’s Hepatitis B webpages.
For more information about Hepatitis B, please visit CDC’s Vaccines and Immunizations webpages.
Carpenter, S. L., Soucie, J. M., Presley, R. J., Ragni, M. V., Wicklund, B. M., Silvey, M., Davidson, H. and the Hemophilia Treatment Center Network Investigators (2014), Hepatitis B vaccination is effective by subcutaneous route in children with bleeding disorders: a universal data collection database analysis. Haemophilia. doi: 10.1111/hae.12569