It is now standard practice to inoculate expectant women in America against influenza between October and May, the period considered to be “flu season” by the American College of Obstetricians and Gynecologists (ACOG) and the Centers for Disease Control and Prevention (CDC).
ACOG, reiterating recommendations from the CDC’s Advisory Committee on Immunization Practice (ACIP), claims that “preventing influenza during pregnancy is an essential element of prenatal care, and the most effective strategy for preventing influenza is annual immunization.”
The number of pregnant women receiving the flu vaccine is on the rise. In 2005, only 16% of pregnant women in the US received a flu shot. Four years later, in 2009, that number had jumped to approximately 50%. Despite the media clamor and the clear recommendations from ACOG and the CDC, some pregnant women are quietly declining the vaccine.
ARE PREGNANT WOMEN REALLY AT MORE RISK?
Though millions of people come down with the flu every year, Robert W. Sears, MD explains that “virtually all cases of the flu pass without consequence.” In reality, the flu poses a real risk mostly to the elderly, many of whom have other health problems. National Center for Health Statistics of deaths from the flu of people of childbearing age shows that flu deaths are rare.
For example, in 2006, the actual number of deaths from flu among all men and women in America ages 15–44 was 29. In other words, if you’re in that age range, your chance of dying from any disease whose symptoms resemble those of the flu is less than one in 10 million.
RARELY A THREAT
The largest scientific study to date, the results of which were published in the American Journal of Perinatology in 2004, examined 49,585 pregnant women who were part of the Kaiser Permanente healthcare organization in Northern California over five flu seasons, as well as 48,639 live births among the same client pool during the same time period.
“Hospital admission with a principal diagnosis of influenza or pneumonia was an extremely rare event for the women in the study population,” wrote the study’s six authors. Only nine women (out of almost 50,000) were admitted, which is 0.018%, or less than one in 5,000; and of those nine women, all had pneumonia. All nine women recovered with no complications.
After conducting an extensive review of all the available scientific literature, David M. Ayoub, MD, and F. Edward Yazbak, MD, came to the same conclusion. Writing in the Journal of American Physicians and Surgeons, they stated: “The [CDC’s Advisory Committee on Immunization Practices’s] citations and the current literature indicate that influenza infection is rarely a threat to a normal pregnancy.”
IS THE VACCINE EFFECTIVE ?
As pointed out by Ayoub and Yazbak, the Kaiser Permanente study of almost 50,000 pregnant women—the largest study to date—found no difference in the incidence of flu or even flu-like illness in those who received the flu vaccine compared to those who did not. This study also found no benefit to the infants of women who had been vaccinated. Nor did vaccination have a positive impact on women with asthma, a subgroup that the CDC claims is at higher risk from influenza.
Another study of vaccine safety during pregnancy, published in the American Journal of Obstetrics & Gynecology in 2005, actually found that there were four times as many hospitalizations related to flu-like illness of women who were vaccinated than of women who weren’t, echoing findings from an earlier study published in 1998 in the American Journal of Epidemiology.
HOW THE FLU VACCINE IS MADE
Part of the reason the flu vaccine is so ineffective is the imperfect way it is manufactured. Influenza is caused by different strains of the influenza virus. Manufacturing the flu vaccine is a bit like forecasting the weather: vaccine manufacturers and researchers try to predict which strains of influenza will be dominant in the coming flu season. Based on their best guesses, they choose three strains to include in the vaccine.
The CDC admits that there are several challenges to creating an effective influenza vaccine, and that vaccine effectiveness is greatly lowered when the strains of influenza in the vaccine are not “well matched” to the strains of influenza in circulation in the population. According to the CDC, “It is not possible in advance of the influenza season to predict how well the vaccine and circulating strains will be matched, and how that may affect vaccine effectiveness.”
EVIDENCE OF HARM
Although the CDC maintains that there is “no convincing evidence of harm” caused by the low doses of mercury in thimerosal-containing vaccines, such as the flu vaccine, the scientific studies that have been done to date have had serious design flaws.
Several years ago, the American Nurses Association (ANA), an organization based in Silver Spring, Maryland, that represents 3.1 million registered nurses, called on pharmaceutical companies to develop seasonal flu vaccines without mercury. In their position statement, the ANA called mercury a “neurotoxicant” and “insist[ed] that pharmaceutical companies develop technology to produce seasonal influenza vaccine without using thimerosal as a preservative and cease using thimerosal as a preservative in vaccines immediately.”
In the package inserts that accompany the flu vaccines being used in 2011, the vaccine manufacturers (CSL Limited, Novartis, GlaxoSmithKline, MedImmune, and Sanofi Pasteur) state that safety studies have not been conducted on pregnant women and nursing mothers.
The insert for the Afluria vaccine, manufactured by the Australian company CSL Limited and distributed in the US by Merck, reads: “Pregnancy Category C: Animal reproduction studies have not been conducted with Afluria. It is also not known whether Afluria can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. Afluria should be given to a pregnant woman only if clearly needed.”
Pregnancy Category C is a Food and Drug Administration classification indicating that no adequate and well-controlled tests of the drug’s effects during pregnancy have been conducted, but that the potential benefits may outweigh the potential risks to a pregnant mother and her fetus.
The package insert for the Fluarix vaccine (manufactured by GlaxoSmithKline), which has been tested on pregnant rats, reads: “Safety and effectiveness have not been established in pregnant women or nursing mothers.”
IN PREGNANCY, LESS IS MORE
We have clear evidence that the flu is usually not dangerous to pregnant women, but we have no clear evidence that the flu shot is safe for them. What we do know is that the less we interfere with a pregnant woman’s bodily integrity, the better the outcome. When you look at the scientific data showing that pregnant women are at no more risk from the flu than non-pregnant women, and that the flu vaccine can be ineffective and may actually cause harm, it is difficult to understand how the government could recommend that pregnant women be vaccinated against influenza.
Jennifer Margulis is the author of The Business of Baby, about how corporations and private interests skew the way we parent in America (Scribner, 2013). A Senior Fellow at the Schuster Institute for Investigative Journalism at Brandeis University, she is a former contributing editor to Mothering magazine and a mother of four. You can read more about her at her website and read more of her writing at her popular blog,