H1N1 Summary Update as of 7/31/09

INDIANAPOLIS, IN - The Novel H1N1 Influenza virus is still provoking severe illness and fatalities in a generally younger population, and cases are expected to increase in the fall.  Influenza viruses are unpredictable, so the symptoms and severity of the disease may change.  Therefore, the extent of the challenges we will face in the weeks and months ahead is unknown, but communication and flexibility will be crucial to accomplishing our mission of slowing and limiting the spread of H1N1.

This summer, the United States has seen high attack rates of illness and hospitalization in younger adults and children, with relatively limited illness or serious consequences in the elderly.  In the Southern Hemisphere, currently in the early phase of their flu season, H1N1 is co-circulating with seasonal influenza in some countries, and is dominating in others.  There also, it is infecting the younger population and sparing the elderly, though the spectrum of disease appears to be the same as in the U.S.

Symptoms:

• . Influenza-like-illness is defined as fever (temperature of 100°F/ 37.8°C or greater) and a cough, and/or a sore throat in the absence of a known cause other than influenza.
• . People experiencing influenza-like-illness are encouraged to call their doctor if they have a chronic illness or are pregnant, or if they have difficulty breathing, chest pain, confusion, or persistent vomiting.

Transmission:

• . Large droplet transmission is confirmed, and occurs when respiratory droplets generated from the source person are transferred to another person primarily during coughing, sneezing, or talking. 
• . Small droplet, fecal/oral transmission is unconfirmed, but remains a possibility.
• . Aerosol spread of influenza virus is dependant upon both ambient relative humidity and temperature. 
• . While both cold and dry conditions favor transmission, Oregon researchers found a significant correlation between "absolute" humidity and influenza virus survival and transmission.  When absolute humidity is low-as in the peak flu months of January and February-the virus appears to survive longer and transmission rates increase. (Transmission 50%, up from 12%, and survival 90%, up from 36%).
• . However, H1N1 is probably in the U.S. during the summer NOT due to better transmission properties, but because it is a novel virus, so more people are susceptible and fewer have immunity. 
• . Incubation period is 2 to 7 days; and the infected person may become contagious anywhere from 1 day before, to 7 days after the onset of symptoms.

Vaccine:

• . Novel H1N1 vaccine is being procured by the U.S. government from five vaccine manufacturers. 
• . The seasonal influenza vaccine should be available earlier than the novel H1N1 vaccine, but the availability of the two vaccines is expected to overlap, very tentatively beginning around mid-October.
• . A maximum of 160 million doses may become available from the five manufacturers over approximately a one month period.   Approximately two doses of inactivated licensed novel H1N1, created from dead viruses and available in multi-dose vials, will be needed per person, with 21 to 28 days between the first and second dose.
• . A limited number of inactivated licensed novel H1N1 vaccines in single-dose syringes will be largely reserved for young children, and pregnant women.
• . Inhaler sprayers with live attenuated vaccine, vaccines containing weakened forms of the organism that causes the disease, will also be available in very limited quantities.
• . Neither the single-dose syringes nor inhaler sprays contain the preservative thimerosal which some people suggest is linked to mental problems in children.
• . The government will be offering the vaccine and ancillary supplies including syringes, needles, sharp containers, and alcohol swabs at no cost.  Gloves and band aids will NOT be provided.
• . Indiana will allocate the state's proportion to each Local Health District (LHD) by county population.

Vaccine Monitoring:

• . Vaccine testing thus far suggests a safe product.  However, the Center for Disease Control (CDC) requires reporting within 48 hours of vaccination on the number of doses administered and the ages of persons vaccinated as such data are critical for assessing early uptake and for adverse event monitoring. 
• . The Vaccine Adverse Event Reporting System (VAERS) serves as the foundation for safety monitoring.  VAERS accepts reports from patients, providers, public health officials, and others.  Indiana State Department of Health (ISDH) Epidemiologists will be monitoring and investigating any reported adverse events related to H1N1 vaccination.  VAERS reporting information is currently available on http://chirp.in.gov and http://vaers.hhs.gov.

Target Populations:
Of the 43,771 U.S. cases, 291 are reported confirmed in Indiana.  Of those 291 Indiana cases, 74% are patients age 18 and under, 40% have asthma or chronic obstructive pulmonary disease (COPD), and 70% have chronic medical conditions (immune deficiencies, obesity, pregnancy, and smoking).  However, fatal H1N1 virus infections have occurred among persons without these conditions who were previously healthy.

Those at greatest risk from the H1N1 virus who will be targeted to receive the vaccine include:

• . Students and staff in K-12 schools (including children over 6months and staff in child care facilities).
• . Health care workers and emergency service workers:  EMT, law enforcement, firefighters, and first responders.  Family members are NOT included as their inclusion would exponentially expand the target population.
• . Pregnant Women (including children 6 months to 4 years not in daycare, new parents, and household contacts of children under 6 months).
• . Those under age 65 with chronic diseases (asthma, COPD, obesity, diabetes, other chronic conditions and immune deficiencies).  People with asthma are especially susceptible to H1N1 influenza, and extremely obese patients have a higher prevalence of comorbid conditions that confer higher risk for influenza complications including chronic heart, lung, liver, and metabolic diseases.

Community Containment Options:

• . Both the ISDH and Local Health Officers may close schools, close churches, and forbid public gatherings (IC-16-19-3-10 and IC-16-20-1-24). However, officials must employ the least restrictive, medically necessary measures to protect public health.
• . Containment measures applied to individuals may have limited impact in preventing the transmission of H1N1 influenza due to the ability of persons with asymptomatic infection to transmit the virus. 
• . The CDC does NOT advise school dismissal for a suspected or confirmed case of Novel Influenza A (H1N1) and, in general, is not advised unless there is a magnitude of faculty or student absenteeism that interferes with the school's ability to function. 
• . Students, faculty or staff with influenza-like illness (fever with a cough or sore throat) should not attend school or go into the community, except to seek medical care, for at least 7 days even if symptoms resolve sooner.  
• . Students, faculty and staff who appear to have an influenza-like illness on arrival, or who become ill during the day should be isolated promptly in a room separate from other students and sent home. 
• . School administrators should communicate regularly with local public health officials to obtain guidance about reporting influenza-like-illness in the school. 

Communication is Key:
. Pay attention to the CDC and directives from the State Health Commissioner.
. Be prepared for changing guidelines, and keep your staff abreast of issues and changes. 
. Be pro-active in your community with information, and work with local schools. 
. Health departments should have easily accessible information and contact information on their websites.