Swine Flu Vaccine: When?

Swine Flu Vaccine Timeline: Key Decisions, Key Milestones

Medically Reviewed by Louise Chang, MD on July 20, 2009

July 20, 2009 -- Pandemic swine flu doesn't worry most Americans. That's likely to change very quickly.

Well before fall 2009, most U.S. schools will open. That's when experts warn the second wave of the pandemic may start sweeping the U.S. If that happens, the U.S. -- as well as the rest of the world -- needs to be prepared for the worst. A pandemic that sickens millions could close schools and businesses, halt travel, and overwhelm health care facilities.

"A pandemic is much more than a health event," Bruce Gellin, MD, MPH, director of the National Vaccine Program Office and deputy assistant secretary of the Health and Human Services Department (HHS) to coordinate U.S. vaccination efforts, tells WebMD. "Given the way a pandemic could play out, it has consequences across government and across society."

The best defense: A vaccine to protect people from swine flu -- before the pandemic peaks. Will there be a vaccine? Perhaps not that soon. And the clock is ticking away the short amount of time before federal officials, including President Barack Obama, have to make hard choices about whether -- and how fast -- to get swine flu shots to everyone who wants one. Or at least to those who most need one.

One choice already is made: The U.S. government has spent $1.15 billion to buy enough vaccine to immunize the entire U.S. population against the new flu. If the government makes the decision to go ahead with a full-scale vaccination program, it would be the largest, fastest vaccination program in world history.

So what will happen, and when? Here's WebMD's timeline, based on meetings and interviews with a number of flu experts. Warning: Flu viruses -- and flu vaccine production -- are notoriously unpredictable. Many things can change, even by the earliest points of this timeline.


Making and Testing the Swine Flu Vaccine

Pandemic swine flu vaccine is already rolling off the production lines of the five different vaccine makers supplying the U.S: 46% will come from Novartis, 26% will come from Sanofi Pasteur, 19% will come from CSL, 6% will come from MedImmune, and 3% will come from GlaxoSmithKline.

By mid-July, clinical tests of the vaccines sponsored by the National Institute of Allergies and Infectious Diseases will begin at the eight Vaccine and Treatment Evaluation Units at Baylor College of Medicine, Houston; Children’s Hospital Medical Center, Cincinnati; Emory University, Atlanta; Group Health Cooperative, Seattle; Saint Louis University; University of Iowa, Iowa City; University of Maryland, Baltimore; and Vanderbilt University, Nashville, Tenn.

The five vaccine manufacturers will also start separate clinical tests in the U.S., Australia, and Europe. These tests will begin in July and August.

On July 29, the CDC's vaccine advisory committee will vote on who should be first in line to get the vaccine. Current indications suggest that children 0 to 4 years old will be will be at the top of the list, followed by school-age children. Children with asthma and pregnant women are also likely high-priority groups, as are critical emergency-response workers.

Preparing the Country for the Swine Flu Vaccine

Beginning with the July 9 Flu Summit, federal health officials stepped up work with state and local officials to lay the groundwork for a massive immunization effort. HHS Secretary Kathleen Sebelius has pledged $7.5 billion in preparedness funds and $350 million in direct grants to states and territories.


Administer Vaccine Now or Later?

By mid- to late-August, seasonal flu vaccine -- the normal, three-in-one vaccine against seasonal flu -- will start arriving. The CDC will recommend people get their flu shots or flu sniffs earlier than usual this year, to make way for possible pandemic flu vaccination.

If there seems to be a huge increase in pandemic flu cases, officials will be tempted to trigger vaccine delivery before safety and efficacy studies are completed.

Would that be safe? The pandemic swine flu bug is a type A H1N1 virus. One of the seasonal flu bugs is a type A H1N1 flu bug. Seasonal vaccine doesn't protect against the new swine flu bug. But there's a long history of safety and efficacy for flu vaccines made of H1N1 antigens, notes flu expert John Treanor, MD, chief of infectious diseases at the University of Rochester, New York.

"You might be sitting at the end of August faced with the decision to do this," Treanor tells WebMD. "If we wait, we can't do vaccination until November. If the pandemic flu follows the seasonal-flu pattern with the bulk of activity in January through March, fine. But if we see this second wave coming in September, we might be faced with the decision to do vaccinations without clinical data."

An HHS advisory committee on July 17 strongly recommended that Sebelius give the green light to vaccine production by Aug. 15 -- before safety and dosing tests are finished. That would mean 60 to 80 million vaccine doses could be ready by Sept. 15.

How fast pandemic flu vaccine gets to people depends on the decision whether to give the vaccine in the traditional way or with something called an adjuvant.

A vaccine includes a piece of virus that evokes a flu-specific immune response. It's called a flu antigen. An adjuvant boosts immune responses to the vaccine and could make the antigen supply go four times as far, allowing the U.S. to share some of its vaccine with the rest of the world. Adjuvant may also elicit broader immune responses, which would be very important if the swine flu virus's genetic code "drifts" a bit before the next pandemic wave.

Vaccinating all Americans would be an effort of historic proportions.

"This would be the largest vaccine drop that has ever happened in the world," says Robin Robinson, PhD. Robinson is the director of the Biomedical Advanced Research and Development Authority (BARDA), the HHS authority that makes sure the nation has the biomedical supplies it needs for emergencies.

"The most we've ever done for seasonal flu vaccine is about 120 million doses in 75 days," he tells WebMD. "At this point, with an antigen-alone pandemic vaccine, we would see about 160 million doses in 30 days. If we go with adjuvant it could be over 300 million in 30 days -- and more coming back behind it."

Making Sure the Vaccine Is Safe

The most important question about a pandemic flu vaccine is whether it will be safe. Unfortunately, like nearly everything about flu bugs, safety can't be guaranteed 100%.

What's reassuring is that there's been no safety issue with previous H1N1 flu vaccines. We take them every year. There are rare adverse events, but the benefit of vaccination far outweighs this small risk.

Safety tests will be performed on the new vaccines. But there won't be a lot of time to see what happens in the long term. If the vaccines seem relatively safe -- that is, if they don't seem harmful in the first weeks after they're administered -- they'll be rolled out on a massive scale. That means relatively rare side effects will be seen only after millions of people are vaccinated.

The last time the nation faced something called swine flu was in 1976. That's when a flu of swine origin struck an army base, triggering fears of a pandemic. A vaccine was rushed into production. Manufacturers demanded that the government indemnify them against possible injury claims, making the public wary before vaccination even began.

It's still not clear why a rare but serious neurological disorder called Guillain-Barre syndrome hit those vaccinated in 1976 at a higher-than-expected rate. But after some 44 million Americans received the vaccine, safety fears scuttled the vaccination program -- and gave "swine flu vaccine" a bad name that still lingers in the American psyche.

How the public perceives the safety of the vaccine will depend on how severe the flu pandemic turns out to be, flu expert Andrew Pavia, MD, said at a June meeting at the Institute of Medicine.

"If this were a 1918-like pandemic, we could tolerate a fair degree of risk," Pavia said. "But for this virus, our sensitivity to risk is going to be much more difficult to calibrate."


One Dose or Two?

By mid-September, results from clinical studies will show the best dose for pandemic swine flu vaccine, how many doses are needed for which populations, and whether the vaccine appears safe in different populations.

If the decision was made in August to start packaging vaccine doses, vaccine will become available around Sept. 15. Early results from clinical trials will guide the decision whether to start vaccinating people. But that decision will have to be made before officials have all the information they'd like to have.

A huge question is whether it will take two doses of vaccine to immunize against pandemic flu. It's possible that because this is a new flu, everyone will be like a small child. Children who've never had a flu shot need two flu vaccinations, weeks apart, to be immunized.

But it might take only one shot. Or maybe some people could get by with one shot -- perhaps those who have had repeated seasonal flu shots, those who have been infected with seasonal H1N1 flu, or those born before 1957 when a different H1N1 flu circulated.

Who Will Want the Swine Flu Vaccine?

A decision will be made whether to deploy pandemic swine flu vaccine for some or all U.S. residents. If that happens, the CDC will begin an intensive campaign to persuade people at high risk of flu complications to get vaccinated. The program will have to address issues of vaccine safety in a straightforward manner. "Public trust is crucial; we risk it at our peril. If we risk public trust with bad vaccination decisions, it will take us years to recover," Pavia warns.

"You are going to have less data than you want to make a decision on the go or no-go, but you are going to have to make it on the best available data at the time," says Gellin. "The middle of September is where all this stuff theoretically converges. That is the point where at least we think we will have preliminary data to see how the vaccine is performing and say where are we with this epidemic and what is the situation."

October Through December

If a vaccine has not already been rushed into use, officials will make final preparations for vaccination programs in early October. This will include a priority list of who gets the vaccine first.

By late November, the first clinical studies of pandemic swine flu vaccine will be completed. If results differ from preliminary findings, vaccination programs will be adjusted.

Early December

Even if unexpected events delay a vaccination program, most experts think vaccine will be ready by the end of December. That means huge numbers of Americans will be offered the vaccine before flu season hits its usual peak in January or February. Even if there's already been a second pandemic wave, this will blunt new waves of pandemic illness.

But will Americans accept a vaccine that arrives after the pandemic peaked? Will safety concerns wreck the expensive program? Even the best laid plans often go awry.

Show Sources


Presentations to the American Committee on Immunization Practices, Atlanta, June 24-26, 2009.

Presentations to the Institute of Medicine Forum on Microbial Threats, June 16, 2009.

Tony Fauci, MD, director, National Institute of Allergy and Infectious Diseases.

Kathleen M. Neuzil, MD, MPH, University of Washington; and chairwoman, ACIP Influenza Workgroup.

Nancy J. Cox, PhD, director, Influenza Division, CDC, Atlanta.

Robin Robinson, PhD, director, Biomedical Advanced Research & Development Authority and assistant secretary for preparedness & response, HHS, Washington, D.C.

Bruce Gellin, MD, MPH, director, National Vaccine Program Office and deputy assistant secretary of health, HHS, Washington, D.C.

John Treanor, MD, professor of medicine, and of microbiology and immunology, University of Rochester, New York.

Andrew Pavia, MD, chief of pediatric infectious diseases, University of Utah, Salt Lake City.

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