Everything You Need to Know About the H1N1 Vaccine

Safety questions are being raised about the rush to get an H1N1 vaccine into the hands of doctors before the virus re-emerges this fall, possibly more dangerous and widespread than it was last spring.

And, those questions are brewing concern among many Americans wondering whether to risk putting off being vaccinated, or take a shot at beating the bug before it gains the upperhand.

Related: Your H1N1 Survival Guide

"They’re pushing it as fast as they can, but they still have to meet good manufacturing standards," said Dr. Peter Gross, senior vice president and chief medical officer at Hackensack University Medical Center.

"It will be tested to make sure it’s safe and contains the proper amounts of protective antibodies," said Gross, who tested flu vaccines for 20 years for the U.S. Food and Drug Administration.

How It’s Being Made

Each year, scientists with the FDA, U.S. Centers for Disease Control and Prevention and the National Institutes of Health, and vaccine manufacturers meet in January or February to decide which strains of the flu virus will be included in the seasonal flu vaccine.

From there, the chosen strains will be sent to the World Health Organization so that its scientists can view the selected strains and make any necessary — though usually minor — changes, said Gross.

"So they really start the process nine months ahead of time," Gross said.

Manufacturers begin making the virus in the spring so that it will be ready to use in the fall.

Like the seasonal flu vaccine, the new H1N1 vaccine will be made using innoculated eggs. The viruses used in the manufacturing process are dead, which means they cannot sicken people who are vaccinated, but will help them build immunity to live viruses — that can be spread from person to person. Unlike, the seasonal flu vaccine, the new H1N1 vaccine will contain just one strain of the flu virus instead of three.

H1N1 Is Nothing New

The H1N1 flu virus has been around for decades in various strains. The new virus, however, is different in that it contains a mix of human, bird and swine strains of the virus.

"An H1N1 strain has been included in the influenza vaccine every year since 1977," Gross said, "which is why the elderly and people in their 50s who have been getting the vaccine for the past 32 years are not really at a significant risk for complications from the novel H1N1 virus, like they are from the seasonal flu."

The process of manufacturing the H1N1 vaccine is also being made over a much shorter time period than the traditional flu vaccine because of fears of what might happen should a fall or winter outbreak occur and no vaccine be available.

"If people aren’t vaccinated, you’re going to see a lot more complications, a lot more hospitalizations," said Gross. "Even so, we have to realize that the experience the U.S. had with novel H1N1 virus is very different than the experience Mexico had. Mexico had a lot more deaths. We’ve had 500 to 600, and I’m not trying to minimize any of the deaths, but that’s not even on par with the seasonal flu, which results in about 35,000 deaths."

The first human volunteers to test the new vaccine were inoculated this month. Most of the volunteers will receive two shots, spaced three weeks apart and it will take another few weeks for volunteers to demonstrate full immunity to the virus if the vaccine works the way it should.

Secretary of Health and Human Services Kathleen Sebelius said Monday that all Americans who receive the vaccine will also need two shots, meaning that if the vaccine arrives on schedule for mid-October, most will not have full immunity to the virus until Thanksgiving.

However, fears that manufacturers are moving too fast may be unfounded.

"If the vaccine passes all of the trials and the only thing that results is a sore arm, then most people who receive the vaccine will probably only receive a sore arm," Gross said. "Serious side effects are rare and we might not know what those will be until 100,000 or a million people are vaccinated. Serious side effects for the polio vaccine were 1 in a million and that’s something you can't figure out until a million people are vaccinated."

Three Shots Instead of One?

Americans are potentially looking at three flu shots this year instead of the normal one shot. That would include one for the seasonal flu, and two for the new H1N1 virus.

Who should consider getting all three?

"Pregnant women, people in their 20s to 40s, very young children and, in contrast to previous years, those above 50 will not need the H1N1 vaccine unless they are in a high risk category or have underlying health problems," Gross said.