Statins may help patients with severe seasonal flu

Oct 29, 2009 (CIDRAP News) – Commonly available drugs that are sold in lower-cost generic versions improve the survival of patients hospitalized for seasonal influenza, researchers reported today, raising the possibility of a widely available treatment that could be used in a severe flu pandemic if other drugs are in short supply.

The research, by the US Centers for Disease Control and Prevention (CDC) and scientists in several states, is part of a slate of new flu reports being presented this weekend at the annual meeting of the Infectious Diseases Society of America (IDSA) in Philadelphia. Also on the agenda: findings that flu vaccination of pregnant women has a protective effect on their babies both before and after birth, and news of what may be the first person-to-person transmission in the United States of H1N1 flu strains resistant to antiviral drugs.

The research presented Thursday examined the effect of the cholesterol-lowering drugs called statins on the clinical course of people who were already taking the drugs and then were hospitalized with lab-confirmed flu infections in the 2007-08 flu season. Those who were already on statins were half as likely to die, Meredith Vandermeer of the Oregon Public Health Division said during a press briefing at the state of the meeting.

The patients were identified via surveillance in 10 states conducted by the CDC’s Emerging Infections Programs; data on their lab results, prescriptions and outcome were drawn from reviews of their medical records. There were 2,800 lab-confirmed cases of flu in the surveillance results, Vandermeer said; 801 of those patients were recorded as taking statins during their hospital stay, presumably because they had been prescribed them before admission. Among the 2,800, 17 people who were on statins died, versus 64 were not on statins. Proportionally, that is 2.1% of those on statins and 3.2% of those not taking the drugs—a risk reduction of approximately half, Vandermeer said.

The connection between statins and flu survival, which has been reported in other research, may be due to the drugs’ ability to damp down the body’s inflammatory response to influenza. But because the study was purely observational, it should not be taken as a recommendation to administer statins during severe flu infection, Vandermeer cautioned: “We encourage further research and randomized controlled trials.”

Vaccine benefits in pregnant women
Protection against flu was also recorded in two separate pieces of research announced Thursday. Researchers from Emory University, the Georgia Division of Public Health and Cincinnati Children’s Hospital Medical Center found that seasonal flu vaccination during pregnancy reduced the chance that a woman would give birth prematurely or to a baby of low birth weight.

That is probably because infections— even mild ones in which the mother does not realize she is ill—reduce the amount of nutrition that flows from mother to fetus, said co-author Dr. Mark Steinhoff of Cincinnati Children’s. But the authors said women are not taking advantage of that protection: There were 6,410 births during the 2-year study, but only 15% of the mothers had been vaccinated during their pregnancies.

In a separate paper, researchers from Yale University School of Medicine found that seasonal flu vaccination during pregnancy appears to protect infants from serious disease during their first 6 months of life, when they cannot receive flu vaccine. In an ongoing, matched case-control study of infants hospitalized for flu or for other reasons, flu vaccine given to the mothers during pregnancy was 85% effective in preventing infants from being hospitalized.

Transmission of resistant H1N1?
The meeting also includes news on H1N1 influenza, though the pandemic is so new that only a few research teams have results. In one report, CDC researchers and North Carolina public health officials describe what may be the first case of person-to-person transmission of Tamiflu-resistant H1N1 flu.

The two resistant cases occurred in June and July in a North Carolina summer camp where 65 campers and staff developed flu and received the drug as treatment, and another 600 were given the drug as a preventative. Two girls who received the drug prophylactically and bunked in the same cabin subsequently fell ill within 3 days of each other.

When the CDC analyzed their respiratory specimens, they were both found to be carrying viruses possessing two mutations that confer resistance to Tamiflu, also known as oseltamivir. Because the girls’ illnesses were so close and they each exhibited both mutations, the CDC assumes that one girl passed the resistant virus to the other, said Dr. Natalie Dailey, a CDC epidemiologist assigned to the North Carolina Department of Health and Human Services.

Finally, researchers from the CDC and the Pennsylvania Department of Health report that children infected with H1N1 flu exhibit the virus on tests and shed it from their respiratory tracts for a median 6 days and up to 13 days after they develop symptoms. That pattern matches what is seen in seasonal flu in children, but is a longer time than is expected in adults, said Dr. Achuyt Bhattarai of the CDC.

Notably, 12 out of 26 children tested during an outbreak in a Pennsylvania elementary school were culture-positive for the presence of flu virus up to 6 days after their fevers resolved. While that does not mean the children were still infectious, the finding deserves further study, Bhattarai said, since current recommendations allow flu victims to return to work or school after 24 hours without fever.

See also:

47th Annual Meeting of the Infectious Diseases Society of America
http://www.idsociety.org

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