The note on the receptionist's desk at my doctor's office was quite emphatic: there was no vaccine to give, either for the H1N1 swine flu or the seasonal variety. If I wanted to yell and scream, the note advised, I should call my congressman, rather than give the staff an earful.

Several explanations can account for the shortfall, including an old-fashioned vaccine production process that requires chicken eggs; overly optimistic predictions of production efficiency; in the case of seasonal flu vaccine, a shift in priorities to H1N1; and a lack of domestic vaccine manufacturers.

The shortage persists, even as many people are avoiding the H1N1 vaccine, a paradox Scientific American predicted would occur in a Perspectives column: "there will be too little vaccine against the novel influenza (H1N1) strain to protect the entire population," and "some people will resist the shots that are offered to them."

Suspicion and fear (and sometimes downright irrationality—check out what commentators like Glenn Beck and Rush Limbaugh have said) permeate the flu vaccine efforts. Last month, New York State dropped the requirement that health workers be vaccinated after an uproar broke out over the rule. The vaccination rate in schools is falling below expectations, the New York Times reports today, as parents resist the immunizations for their kids, the population that is not only the most susceptible but also the one that primarily drives flu outbreaks.

An easy way to boost the vaccine supply is to use adjuvants, ingredients that increase the effectiveness of a vaccine. That enables less immune-stimulating antigen to be used in each shot, thereby stretching the supply [see the article "Boosting Vaccine Power" from the November 2009 issue]. Yet despite some significant funding for adjuvants, the U.S. has resisted them in this pandemic, arguing that the safety data accumulated thus far is inadequate.

That position puzzles European nations, which have put adjuvants in vaccines for years, the Wall Street Journal points out today. The U.S. is "very, very conservative. And far beyond what I think is reasonable," said David Fedson, a vaccine expert who served on the U.S. advisory committee on immunization practices, in the WSJ story. "In a mild pandemic maybe it doesn't make a difference. In a major pandemic, maybe it could make a difference." Also, memories of the 1976 swine flu vaccination campaign and the lawsuits from families of people who developed a rare neurological disorder (Guillain-Barre syndrome) after being immunized have led health officials to stay with the tried-and-true methods of vaccine production, leaving out exotic additives.

On Monday, Kathleen Sebelius, head of the U.S. Department of Health and Human Services, announced that the U.S. had received 16.5 million H1N1 vaccine doses (earlier, officials predicted 45 million doses by mid-October). Counseling patience, she stated that there would eventually be enough for everyone who wants it—which a cynic could interpret as there being enough when no one needs it.

Although H1N1 has claimed about 1,000 lives in the U.S. thus far, thankfully, the virus is nowhere near as deadly as past pandemics, because human immune systems have already been primed by exposure to its ancestors, which includes the 1918 flu virus. As far as pandemics go, this one is a good one to learn from—as influenza experts will tell you, somewhere, at some time, is a virus out there with humanity's name on it.

False-color image of H1N1 virus from the U.S. Centers oof Disease Control and Prevention