Why isn't there a cure-all influenza vaccine?

Previously published Slate articles made new.
April 27 2009 3:25 PM

Why Isn't There a Cure-All Influenza Vaccine?

Because it wouldn't be safe.

Click here to read more from Slate on the swine flu. 

Strains of swine flu have been confirmed in the United States, Mexico, and Canada, prompting the United States to declare a public health emergency. The particularly virulent strain is believed to have caused the deaths of up to 103 people in Mexico and infected more than 1,000, causing heightened concern about a potential epidemic in countries around the world. In an "Explainer" published last winter, Michelle Tsai explained why they don't cram every strain of influenza into our yearly flu shots. The column is reprinted below.

The flu shot protects against only 40 percent of this year's viruses, the Centers for Disease Control said last week. On Thursday, the FDA decided to replace all three of the vaccine's influenza strains for next winter. Wait, why can't the scientists put every strain there is into the vaccine?

Advertisement

It wouldn't be worth the effort, even if it were feasible. There are thousands of influenza subtypes infecting people around the world, but very few are likely to make someone in the United States sick. Vaccinating people against a disease they're never going to get is a risky proposition: We don't know how the body would respond to a barrage of flu vaccinations. The patient might also develop a strong immune response to an insignificant strain, while skimping on antibodies for a nastier virus.

That's not to say that we're better off putting just three strains of influenza in a vaccine. Five or six might offer better protection than what we have today without running afoul of the problems described above. But there are other reasons not to cram more into the flu shot: For each added strain, you need about 15 micrograms of protein, so a diverse vaccine yields a larger dose. This means it might hurt more when you get a flu shot, or you might need to get multiple shots. People could also suffer greater side effects and allergic reactions. Some scientists are investigating universal flu vaccines, which work in a different way; the new shots under development target proteins that don't change much between different strains, meaning a single vaccine could protect against many strains.

In the meantime, there's the matter of manufacturing the extra strains. Pharmaceutical companies already have their hands full developing vaccines for just three forms in the United States. (Just four years ago, a national shortage forced government officials to discourage Americans from getting shots unless they were sick, infants, or elderly.) To make a single vaccine dose for a given strain, the virus must be injected into a chicken embryo; to manufacture enough doses for the whole country can take half a year. But the drug companies don't have enough eggs to make vaccines for 20 distinct viruses, let alone thousands. (There's reason for hope, however. By using bacteria, yeast, or mammalian cells to incubate viruses, scientists may be able to speed up production significantly.)

Developers would also need to undergo a lengthy process to show their new product is safe. Even if it did get approval in time for flu season, manufacturing costs would be much higher. That could make the flu shots more expensive for patients and result in fewer doses being administered.

Got a question about today's news? Ask the Explainer.

AP video: Obama addresses the swine flu outbreak.

TODAY IN SLATE

Politics

Meet the New Bosses

How the Republicans would run the Senate.

It Is Very, Very Stupid to Compare Hope Solo to Ray Rice

The U.S. Is So, So Far Behind Europe on Clean Energy

Even if You Don’t Like Batman, You Might Like Gotham

Friends Was the Last Purely Pleasurable Sitcom

The Eye

This Whimsical Driverless Car Imagines Transportation in 2059

Medical Examiner

Did America Get Fat by Drinking Diet Soda?  

A high-profile study points the finger at artificial sweeteners.

A Woman Who Escaped the Extreme Babymaking Christian Fundamentalism of Quiverfull

Nicolas Sarkozy, Thrice Married, Says Gay Marriage Humiliates the Family

  News & Politics
Over There
Sept. 22 2014 1:29 PM “That’s Called Jim Crow” Philip Gourevitch on America’s hypocritical interventions in Africa.
  Business
Moneybox
Sept. 22 2014 1:37 PM Subprime Loans Are Back! And believe it or not, that’s a good thing.
  Life
Outward
Sept. 22 2014 4:45 PM Why Can’t the Census Count Gay Couples Accurately?
  Double X
Doublex
Sept. 22 2014 4:06 PM No, Women’s Soccer Does Not Have a Domestic Violence Problem Or, why it is very, very stupid to compare Hope Solo to Ray Rice.
  Slate Plus
Slate Plus
Sept. 22 2014 1:52 PM Tell Us What You Think About Slate Plus Help us improve our new membership program.
  Arts
Brow Beat
Sept. 22 2014 3:16 PM Watch the Best Part of Beyoncé and Jay Z’s On the Run Tour
  Technology
Future Tense
Sept. 22 2014 12:14 PM Family Court Rules That You Can Serve Someone With Legal Papers Over Facebook
  Health & Science
Medical Examiner
Sept. 22 2014 4:34 PM Here’s Where We Stand With Ebola Even experienced international disaster responders are shocked at how bad it’s gotten.
  Sports
Sports Nut
Sept. 18 2014 11:42 AM Grandmaster Clash One of the most amazing feats in chess history just happened, and no one noticed.