Between checking out new casinos online and doing some research about overcoming food allergies (if that’s possible), I couldn’t help but delve deeper into the issue of vaccines for people with egg allergies.

If you’re allergic to eggs, you’ll definitely want to check with your doctor if you’re planning to get a yellow fever vaccine. The vaccine may be less likely to cause a severe allergic reaction when you get it with a different type of egg white, a new study suggests.

For years, egg allergies have been one of the main reasons doctors recommend a yellow fever vaccine instead of a yellow fever vaccine with egg protein. But it’s been unclear why people with a egg allergy react differently to the two different kinds of vaccines.

Chiara Bonini, a researcher at the Institut Pasteur in Paris, set out to answer the question. She enrolled 51 people with egg allergies, 34 who had a history of egg allergy but no current food allergy and 29 without a history of egg allergy. None of the participants were pregnant.

Bonini randomly assigned the participants into two groups. One group got the yellow fever vaccine with an egg-based vaccine stabiliser (made from egg protein) and the other group got the vaccine without a stabiliser (made from egg protein). All participants had an IgE (or antibody) test. If the protein from the egg protein reacted with an IgE test, the participants had to get the vaccine without stabiliser.

A group of 51 people with egg allergies was randomly assigned into two groups. All had blood tests to measure their immune system. The lower panels show blood tests from before the vaccine. The upper panels show blood tests a few weeks after getting the vaccine. The yellow arrows show IgE levels before the vaccine. A higher level is an allergy. Source: Bonini et al., PLOS One, 2017

Before the immunisation, some of the participants were given either a placebo shot (without a stabiliser) or the egg-based vaccine with a stabiliser. Those who got the egg-based shot had significantly higher levels of an antibody called IgE after the vaccine than those who received the placebo, the researchers found.

Eggs also make proteins that interact with immune system cells, and that can lead to inflammation. When egg proteins interact with the immune system, their responses can be “alarmingly rapid,” Bonini said.

In previous studies, it had been shown that immunisation with the egg protein stabiliser was more effective in people who were allergic to eggs. The new results show that it’s the other protein that’s giving the immunisation more potency, Bonini said.

“It appears that the immunisation with a [stabiliser] containing egg protein was less effective for people with egg allergy and more effective for people without egg allergy,” Bonini said.

These findings suggest that an egg-free stabiliser may help reduce the risk of allergic reactions to the vaccine, according to the study. The researchers are planning to test a different stabiliser in a larger study.

The need to introduce such a supplement is growing, since the yellow fever vaccine is currently manufactured with an egg-based stabiliser and isn’t approved in the U.S.

Zoe Kickhefer