HIV/AIDS Doesn't Increase Swine Flu (H1N1) Death Risk, Study Suggests

Having HIV doesn't make you any more likely to die from H1N1 influenza (also known as swine flu), according to a new French study.1

Many HIV-positive people had feared that HIV might be among the "underlying conditions" that have been named as cofactors in at least 49 percent of the documented fatal cases of H1N1 worldwide.

But in their study, which reviewed deaths associated with H1N1, researchers from the French Institute for Public Health Surveillance noted that "diseases most frequently associated with death [from H1N1] were the same as those identified for death from seasonal influenza." However, the researchers emphasized that there's still much we don't know about the H1N1 pandemic, since we've only had a few months of experience with it.

Reprinted with permission from Laetitia Vaillant, Pharm.D.

Reprinted with permission from Laetitia Vaillant, Pharm.D.

The researchers said that, between April and mid-July 2009, there were a total of 684 confirmed HIN1 deaths in 28 countries. Due to what they said was a "significant amount of missing data," the researchers only analyzed 331 cases of people who died and were also noted to have an underlying disease.

They found that "metabolic conditions" (usually obesity, diabetes or both) were the most common underlying health risks in the cases they had data for, accounting for 57 of the people who had died. The World Health Organization defines "obesity" as having a body mass index of 30 or more, but different countries and localities may have used different definitions.

Reprinted with permission from Laetitia Vaillant, Pharm.D.

Reprinted with permission from Laetitia Vaillant, Pharm.D.

HIV was never mentioned in the study. In fact, the researchers say it was not mentioned in any of the collected data. Under a category called "immunodepression" were 16 people who had died: They included five who had cancerous tumors and two who had undergone a transplant operation. In just two people categorized as having "immunodepression," HIV/AIDS could not be excluded, according to Laetitia Vaillant, Pharm.D., an epidemiologist and the lead author of the report.

In addition, 19 people with "infectious diseases" died, including six who had bacterial infection (Streptococcus and Staphylococcus), three with tuberculosis and three with other conditions. Details were unavailable for six people.

Of the 343 fatal swine flu cases (about half of the total number of people who died) for which the researchers had individual data regarding the person's age, the average age was 37 years old. Overall, the majority of the deaths (51 percent) occurred in the 20-to-49 age group. However, this depended on where in the world someone was. For example, in the U.S., 47 percent of deaths were in the 20-to-49 age group, but in Canada, just 32 percent were. (By contrast, 36 percent of deaths in Canada were among people age 60 or greater, most of them women.)

As a side note, many of the women who died from swine flu were either pregnant or had just delivered a baby when they died: 16 women in total, half of whom had other health complications. The researchers were not surprised by this finding; they noted that pregnancy is a typical risk factor during the typical flu season.

Understanding the Results

The image is of H1N1 (swine) flu virus taken in the CDC Influenza Laboratory.

The image above is of H1N1 (swine) flu virus taken in the CDC Influenza Laboratory.

The researchers were not sure why obesity/diabetes appeared to be a major underlying condition among the people who died from H1N1, although they offered three possible explanations. First, the risk may be linked with typical obesity complications when someone is hospitalized and in intensive care. Second, it could be the diabetes that makes H1N1 more lethal, since obesity is often paired with diabetes. Finally, being obese could interfere with the immune response to H1N1, causing H1N1 infection to be more severe.

Understanding exactly who is at risk for a more severe experience with H1N1 is critical, since another wave of this flu is expected to hit the Northern Hemisphere in the next few months. This report may offer some guidance as policy experts and health care professionals make recommendations on who should seek out medical help quickly if they start to develop flu symptoms, as well as who should move to the front of the immunization line once an H1N1 vaccine is available. Hopefully, worldwide agencies charged with collecting these data will be ready to step up to the plate once flu season hits and provide more accurate numbers than were available for this study.

Although this study found no link between HIV and the risk of death from swine flu, immunosuppression (having a low CD4 count) is known to be a risk factor for influenza in general.

Some countries, including the U.S., Canada and the United Kingdom, have announced that if you are HIV positive, you are part of the priority group to receive a flu vaccination when it's been developed. So if you are HIV positive, be sure to get vaccinated -- not just for H1N1, but for the seasonal flu as well.

For More Information

The full report is available online in the Aug. 20, 2009 issue of Eurosurveillance.

For more information on H1N1 flu, visit our library of articles.

To calculate your body mass index (a key indicator of obesity), use this tool from the U.S. National Heart Lung and Blood Institute.


  1. Vaillant L, La Ruche G, Tarantola A, Barboza P, for the epidemic intelligence team at InVS. Epidemiology of fatal cases associated with pandemic H1N1 influenza 2009. Euro Surveill. 2009;14(33):pii=19309.