Levy is encouraging pregnant women to consider the adjuvanted vaccine.

The Public Health Agency of Canada has promised to give these groups the option of getting an H1N1 shot that does not contain adjuvant — a chemical that boosts a vaccine’s effectiveness — given that little research has been done on how these two groups respond to adjuvanted flu vaccines. Some animal studies, which are less reliable than studies conducted in humans, have raised the possibility that adjuvants might cause autoimmune diseases.

But since the unadjuvanted H1N1 vaccine is not expected to be available for two more weeks, pregnant women are suddenly left to weigh the risks and benefits of being inoculated sooner with an adjuvanted vaccine whose safety has not been entirely proven.

The issue could come down to whether a woman fears the effects of the H1N1 flu more than the vaccine.

Levy is encouraging pregnant women to consider the adjuvanted vaccine.

“The adjuvanted vaccine is available and can be used by pregnant women. The adjuvant has been used in other countries in many, many doses without known adverse side effects,” said Levy.

He added the benefits of the vaccine outweigh any “theoretical” risks, especially if women are entering the second half of their pregnancy, or have an underlying medical condition.