Health Alerts > 9/21/09 H1N1 status report

 GLOBAL UPDATES: 

• The 2009 H1N1 influenza virus remains the predominant influenza virus in circulation worldwide and has not demonstrated significant mutation.

NATIONAL UPDATES:

On September 15, 2009 the The U.S. Food and Drug Administration approved four vaccines against the 2009 H1N1 influenza virus. The vaccines will be distributed nationally after the initial lots become available, which is expected within the next four weeks.

Current Flu Epidemiology

As of September 12th:

a.        99% of all subtyped influenza A viruses being reported to CDC were 2009 influenza A (H1N1) viruses (pandemic flu virus).

b.       CDC estimates well over 1 million are infected in US

c.        Two influenza-associated pediatric deaths were reported, and both were associated with 2009 influenza A (H1N1) virus infection. Since September 28, 2008, CDC has received 114 reports of influenza-associated pediatric deaths that occurred during the current influenza season (25 deaths in children less than 2 years, 12 deaths in children 2-4 years, 34 deaths in children 5-11 years, and 43 deaths in individuals 12-17 years). Forty-six of the 114 deaths were due to 2009 influenza A (H1N1) virus infections.

d.       The proportion of outpatient visits for influenza-like illness (ILI) was above the national baseline, but Indiana still reports sporadic flu activity.

e.        The 2009-10 influenza season officially begins October 4, 2009.

f.         The majority of 2009 influenza A (H1N1) viruses are susceptible to the neuraminidase inhibitor antiviral medication Oseltamivir; however, rare sporadic cases of Oseltamivir resistant 2009 influenza A (H1N1) viruses have been detected worldwide, including 10 cases in the United States. 

New Recommendations:

Pregnant Women and H1N1 Vaccine (Update) (http://www.cdc.gov/H1N1flu/vaccination/pregnant_qa.htm)

According to the CDC, it is important for a pregnant woman to receive the 2009 H1N1 influenza vaccine as well as a seasonal influenza vaccine. Pregnant women who are otherwise healthy have been severely impacted by the 2009 H1N1 influenza virus (formerly called “novel H1N1 flu” or “swine flu. Six percent of confirmed fatal 2009 H1N1 flu cases thus far have been in pregnant. People can receive both the seasonal and H1N1 flu shot at the same time, but in different arms.

While there is no evidence that thimerosal (used as a preservative in vaccine packaged in multi-dose vials) is harmful to a pregnant woman or a fetus,  some women are concerned about exposure to preservatives.   Therefore, manufacturers will produce preservative-free seasonal and 2009 H1N1 influenza vaccines in single dose syringes for pregnant women and small children. CDC recommends that pregnant women may receive influenza vaccine with or without thimerosal.

Pregnant Women and Antivirals (Update) (http://www.cdc.gov/h1n1flu/pregnancy/antiviral_messages.htm)

• Pregnant women are at higher risk for severe complications and death from influenza, including both 2009 H1N1 influenza and seasonal influenza.
• Treatment with Tamiflu or Relenza is recommended for pregnant women with suspected or confirmed influenza and can be taken during any trimester of pregnancy. The duration of antiviral treatment is 5 days.
• They are both "Pregnancy Category C" medications, indicating that no clinical studies have been conducted to assess the safety of these medications for pregnant women. However, the available risk-benefit data indicate pregnant women with suspected or confirmed influenza should receive prompt antiviral therapy. Pregnancy should not be considered a contraindication to their use.
• Treatment should be initiated as early as possible because studies show that treatment initiated early (i.e., within 48 hours of illness onset) is more likely to provide benefit.
• Treatment should not wait for laboratory confirmation of influenza because the sensitivity of rapid tests can range from 10 % to 70%.

Guillain-Barré syndrome (GBS) and flu Vaccine (http://www.cdc.gov/h1n1flu/vaccination/gbs_qa.htm)

What happened in 1976 with GBS and the swine flu vaccine?
Scientists first reported a suspected link between GBS and vaccinations in 1976, during a national campaign to vaccinate people against a swine flu virus. The investigation found that vaccine recipients had a higher risk for GBS than those who were not vaccinated (about 1 additional case occurred per 100,000 people vaccinated).  Given this association, and the fact that the swine flu disease was limited, the vaccination program was stopped. Since then, numerous studies have been done to evaluate if other flu vaccines were associated with GBS. In most studies, no association was found, but two studies suggested that approximately 1 additional person out of 1 million vaccinated people may be at risk for GBS associated with the seasonal influenza vaccine.

Why did some people develop GBS after they received the 1976 swine flu vaccine?
The Institute of Medicine (IOM) conducted a thorough scientific review in 2003 and concluded that people who received the 1976 swine influenza vaccine had a slight increased risk for developing GBS. Scientists have multiple theories on why this increased risk may have occurred, but the exact reason for this association remains unknown.

Do you expect that the 2009 H1N1 vaccine will be associated with GBS?
We expect the 2009 H1N1 vaccine to have a similar safety profile as seasonal flu vaccines, which have very good safety track records. The seasonal influenza vaccine has not been consistently associated with GBS. Although we do not expect GBS cases to occur after vaccination with the 2009 H1N1 vaccine, we will be closely monitoring for any cases out of an abundance of caution. If there is an increase in the number of reported cases, public health officials will conduct intensive investigations. If any problems are detected with this 2009 H1N1 vaccine, they will be reported to health officials, healthcare providers, and the public, and health officials will take needed action to ensure the public's health and safety.

LOCAL EFFORTS:  We have not received H1N1 vaccine as of yet.  We anticipating that it will be available some time in October and will make you aware as soon as we know.

Deb McMahan, MD