H1N1 (Swine Flu) and Food Allergy

in Food Allergy
Published: July 2, 2010

Background: The vaccine against the H1N1 flu (formerly known as swine flu) became available in 2009 to fight a flu pandemic. It is now part of the regular quadrivalent flu vaccine given seasonally in the U.S. and Canada. This archived article addresses ingredient questions that arose. Today, there are now egg-free flu vaccines as well, as described by the CDC here.

Frequently Asked Questions:

Q. Does the H1N1 vaccine contain egg?

A. The H1N1 vaccine was developed using the egg-based production method. This means the vaccine viruses are grown in eggs. This is true for the regular flu shot as well.

The manufacturer states the level of ovalbumin (egg protein) in the adjuvanted vaccine is generally below 5-10 ng/mL. The ovalbumin level is not yet available for the unadjuvanted version of the vaccine, which is offered to pregnant women.

In an official statement to physicians, the CSACI allergist organization says the risk of a reaction to the H1N1 vaccine (or the regular flu vaccine) in most egg-allergic patients appears to be quite low, when proper risk-reduction measures are in place.

Allergist Dr. Wade Watson says people who have had a recent or serious reaction to egg should contact their allergist to discuss their options. Lower-risk individuals can get their vaccine at a regular clinic, as long as there is a doctor’s supervision, access to epinephrine, and the egg-allergic person is observed after being given the shot. In fact, the vaccine should always be given under observation, regardless of a previous history of allergic reaction.

For greater detail on assessing egg allergy risk and risk-reduction measures, see the U.S. Centers for Disease Control advice here, and the allergists’ practice parameters here.

Q. Have any studies been done on egg allergies and the vaccine?

A. A group of allergists in Quebec studied the tolerance of the H1N1 vaccine in egg-allergic individuals. The CMAJ website reported in December 2010 that, in a trial of 952 people, none had an anaphylactic reaction to the shot. Two had skin reactions treated with Benadryl.

Q. Are there other allergy concerns with the vaccine?

A. The vaccine adjuvant (called AS03) contains two ingredients that have been of some concern to people with allergies. The first is squalene, derived from shark liver oil. Both allergist Dr. Richard Warrington and a representative from GlaxoSmithKline, the makers of the vaccine, say there is NO risk to people with fish allergy.

Squalene is a fat, and it is protein that causes allergic reaction. Furthermore, the squalene is highly purified and any protein traces will have been removed. Dr. Warrington also adds that the antibodies found in fish allergic subjects show very limited cross-reactivity with shark protein.

The second ingredient that has raised concern is tocopherol (vitamin E) which is sometimes derived from soybean oil or seeds. A representative from GlaxoSmithKline states that the tocopherol in the adjuvant is synthetic, and does not contain any plant- or animal- derived components or proteins.

Q. If my child can’t receive the vaccine, can he/she still be protected from H1N1?

A. If your child is unable to receive the H1N1 vaccine for allergy reasons, there are other measures that can be taken to protect him or her from contracting the flu, says Dr. Sharon Dell, an expert in airway diseases at the Hospital for Sick Children in Toronto. For one, she suggests that if all the other members of the child’s family get the vaccine, then that would provide some protection.

Furthermore, “meticulous hand washing” and avoiding contact with other people who are sick will also help.
If the child has reacted to a previous vaccine, but it’s unclear what the cause of the reaction was, he or she could be skin-tested to this particular vaccine first, and could receive the vaccine if there’s no indication of reaction.

Anti-Viral Drugs

If you haven’t had the vaccine and contract the flu, a doctor may prescribe an anti-viral medication to reduce your symptoms. Or an anti-viral might be prescribed as a “prophylaxis”, which means, to reduce the likelihood that you will contract the virus. (This would likely be to stop the spread of the flu in a setting such as a hospital.)

Q. What are the anti-viral medications?
The two anti-virals that are available are called Relenza and Tamiflu. Tamiflu is taken orally, while Relenza is an inhaled powder. (The makers of Relenza caution those with asthma that the drug has caused exacerbations in some people.

Q. What if I am allergic to an ingredient in the influenza anti-viral medications?
If you are allergic to an ingredient in a medication, the general advice is to avoid it, says Dr. Michael Cyr, an allergist in Hamilton, Ontario. However, if the benefits of taking the anti-viral outweigh the risk, then the medication should be taken under the supervision of an allergist or a physician who has the ability to treat the reaction.
If there is no reaction, says Dr. Wade Watson, a pediatric allergist in Halifax, the medication can be continued.

Q. What are the ingredients of the anti-viral medications?
Relenza contains lactose (dairy protein) and Tamiflu contains corn starch and gelatin, which are allergens for some people. See the full list of ingredients here.

See Also:
CDC – All About the H1N1 flu of 2009-10 and the vaccine.
CDC – Key Facts about seaonal flu vaccines.

Centers for Disease Control and Prevention (CDC).
E-mail interviews with allergist Dr. Wade Watson, Dr. Richard Warrington, Dr. Michael Cyr and Dr. Antony Ham Pong.
H1N1 media call with experts at  The Lung Association of Canada