Activity Update

·         Influenza illness, including illness associated with the novel influenza A H1N1 virus is ongoing in the United States.

·         The states that have reported the most novel H1N1 activity are Arizona, California, Illinois, New York, Texas, Washington state and Wisconsin.

·         During week 19 (May 10 - 16, 2009), the May 22 FluView Report shows that influenza activity decreased in the United States, however there are still higher levels of influenza-like illness than is normal for this time of year.

 

·         15.1% of specimens tested by U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories and reported to CDC/Influenza Division were positive for influenza.

 

·         Novel H1N1 viruses now make up 90% of all viruses analyzed by the U.S. WHO/NREVESS collaborating laboratories.

·         Overall the nationwide level of outpatient visits to providers for influenza-like-illness is back below the national baseline and seems to be trending downward.

·         Only one region (Region I) was slightly above baseline for patient visits for influenza-like-illness.

·         Region I includes Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island and Vermont.

·         Two regions showed an increase in influenza-like illness activity: Region I and Region II, which is significant.

·         Region II includes New Jersey and New York.

·         So despite the aggregate downward trend, localized outbreaks – in some case with intense influenza-like activity – are ongoing in some places, including New York City.

·         It’s likely that localized outbreaks have fueled the increase in influenza-like-illness noted in Regions I and II.

·         Schools in some states continue to close as a result of novel H1N1 flu activity based on local considerations.

·         18 states in the U.S. are reporting widespread (5) or regional influenza (13) activity at this time. (This is down from 22 states last week, but still much higher than we would normally expect for this time of year.)

·         The five states reporting widespread influenza activity are Arizona, California, New Jersey, Texas and Virginia.

·         This is very unusual for this time of year to still be having so many states reporting regional and widespread activity.

·         The proportion of deaths attributed to pneumonia and influenza (P&I) was below the epidemic threshold.

·         Two influenza-associated pediatric deaths were reported. One of these was reported to have been caused by a seasonal influenza B virus. Testing on samples in the second case are still pending.

·         It’s uncertain at this time how severe this novel H1N1 outbreak will be in terms of how many people infected have severe complications or death related to novel H1N1 infection.

·         It is a good sign that nation-wide influenza-like-illness surveillance is trending downward.

·         However, localized outbreaks are likely to occur over the summer.

·         The real uncertainty is the fall and how the novel H1N1 virus will affect our influenza 2009-2010 influenza season.

·         We are still learning about the severity and other epidemiological characteristics of the novel H1N1 virus.

·         This information is important and will be taken into account when making recommendations with regard to vaccine and other preventive measures in the fall.

·         So far, the largest number of novel H1N1 confirmed and probable cases (more than 60% of cases) have been in people between the ages of 5 years and 24 years old.

·         However, nearly 40% of hospitalizations have occurred in people between the ages of 19 and 49 years of age. And about 18% of hospitalized patients have been between the ages of 10 and 18 years old. Only 13% of hospitalizations have occurred in people 50 years and older. This is unusual compared to seasonal flu, where about 60% of people who are hospitalized are 65 years and older.

·         Pregnancy and other previously recognized medical conditions from seasonal influenza appear to be associated with increased risk of complications from this novel H1N1 as well. 

 

·         Seventy-one percent (71%) of hospitalized patients have had underlying chronic medical conditions.

·         Reported deaths have occurred in people ranging in age from 22 months old to 57 years old, which is again atypical of seasonal flu where the mortality burden falls mainly on people 65 and older.

·         But we don’t know whether this is because older people may have some pre-existing protective antibody to this virus, or it’s just that the virus has not yet spread significantly to this segment of the population.

·         Some recent results of an antibody study conducted by CDC have shown that:

o        Children have no existing antibody to the novel H1N1 flu virus.

 

o        Some younger adults had a low level of cross-reactive antibody against the novel H1N1 flu virus.

 

o        About one-third of adults older than 60 years of age had cross-reactive antibody against this novel H1N1 virus.

 

o        However, it is unknown how much, if any, protection may be afforded against the novel influenza A (H1N1) by existing antibody.

 

o   A possible explanation to this preexisting antibody in adults is that they may have had previous exposure, either through infection or vaccination to an influenza A H1N1 virus that was more closely related to the novel H1N1 flu virus than are contemporary seasonal influenza A (H1N1) strains.

 

o   More information about this study is available in the May 22 issue of the MMWR in the article entitled “Cross-reactive Serum Antibody Response to the Novel Influenza A (H1N1) Virus After Vaccination with Seasonal Influenza Vaccine.”

Vaccine

 

·         Vaccines are a very important tool for the prevention of influenza, including novel influenza that may become pandemic.

 

·         CDC has isolated the novel H1N1 flu virus and is working to make a candidate vaccine virus that can be provided to industry so that manufacturers can scale up for production of a vaccine, if necessary.

 

·         CDC is hopeful that we will have vaccine viruses to send to manufacturers by the end of May.

 

·         This is within original timelines sent out by CDC.

 

·         There are many steps involved with producing a vaccine, and we are committed to working with the NIH, FDA, BARDA, WHO and the manufacturers of influenza vaccines through this process.

·         If things go well, and a decision is made to seek full scale vaccine production, it will be several months until the vaccine will be available.

·         So a vaccine is an important tool for the future.

Seasonal Flu Vaccine 

 

·         Production of the seasonal flu vaccine for next season is nearly complete and will be completed.

 

·         Seasonal flu is responsible for causing an estimated 36,000 flu-related deaths and 200,000 flu-related hospitalizations in the U.S. each year.

 

·         Seasonal flu vaccine is always a public health priority.

 

·         Based on serology data, CDC does not believe that seasonal influenza vaccine will provide any meaningful protection against novel influenza A (H1N1) virus.

 

·         Vaccination with seasonal vaccine is still recommended to protect against the seasonal influenza viruses in the vaccine.

 

·         More information on the serology data as it relates to seasonal vaccine is available in the May 22 issue of the MMWR in the article entitled “Cross-reactive Serum Antibody Response to the Novel Influenza A (H1N1) Virus After Vaccination with Seasonal Influenza Vaccine.”

 

Stay Home If You Are Sick: Don’t Travel

·         To help control the spread of novel H1N1 flu, people who are sick with flu-like symptoms should stay at home except to seek medical care or for other necessary reasons.

·         The symptoms of this new H1N1 flu virus in people are similar to the symptoms of seasonal flu and include fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills and fatigue. A significant number of people who have been infected with this virus also have reported diarrhea and vomiting.  

·         Staying at home means that you should not leave your home unless you need to go to the doctor. This means avoiding normal activities, including work, school, travel, shopping, social events, and public gatherings.

·         If you are sick, CDC recommends that you stay home for 7 days after your symptoms begin or until you have been symptom-free for 24 hours, whichever is longer. This is to keep from spreading the virus to other people.

·         Resting at home will also help you feel better sooner.

·         Even if you start to feel better during this period, it is important that you stay home for the recommended time except to seek medical care or for necessities. You should not travel, go to work or school, or run errands.

·         If people with flu-like illness must leave their home (for example, to seek medical care or other necessities) they should cover their nose and mouth when coughing or sneezing. A surgical loose-fitting mask can be helpful for people who have them, but a tissue or other covering is appropriate as well.

·         If you get sick with flu-like symptoms and have a trip scheduled, you should not travel until 7 days after your symptoms begin or until you have been symptom-free for 24 hours, whichever is longer.

·         If you get sick during a trip, you should stay in your hotel room for 7 days after your symptoms begin or until you have been symptom-free for 24 hours, whichever is longer (except to seek medical care or other necessities).

·         Have you ever worried that you may become sick because you had to sit close to someone who was sick on a plane, in the office, or at school? Remember that if you were healthy, you would want sick people to stay at home instead of traveling and risking the health of others.

·         If you are sick, think about your fellow passengers before you travel. Do your part -- stay home, recover, and keep others well.

·         For more information about healthy and safe travel visit www.cdc.gov/travel or call 1-800-CDC-INFO

·         There is no vaccine yet and antiviral drugs may be difficult to get when traveling.

School Closures

·         We know that children are susceptible to novel H1N1 flu, and schools or childcare facilities may act as a point of spread.

·         As we know from seasonal flu, schools are a challenge. Aside from closing schools for an extended period of time in coordination with other means to reduce spread in a community, there is no approach that will completely stop or prevent transmission of flu in a school setting.

·         There is a need for localized responses in schools, and when absentee rates are increasing in students and staff due to novel H1N1 flu illness, it is appropriate to close schools if they are not able to function.

·         On May 5, CDC issued updated guidance for schools impacted by novel H1N1 flu infections. This guidance attempts to strike a balance between measures that may have an effect on slowing transmission and those that create other problems (such as disrupting education and sending kids to malls or other social gathering spots where they’d still be susceptible.)

·         In the updated school guidance, CDC recommends that parents and guardians should monitor their school-aged children, and faculty and staff should self-monitor every morning for symptoms of flu-like illness.

·         CDC understands that parents are concerned about how to protect their children from novel H1N1 flu and other infectious diseases.

·         As much as we wish there was, there is no approach that will guarantee protection from infectious diseases spread by flu viruses.

·         This is why CDC is working to develop a vaccine for the novel H1N1 flu virus. Vaccines are not 100 percent effective, but they provide the best protection against viruses, such as flu.

·         Antiviral medications can also be used to treat flu illness, and in some cases, to prevent flu infection. Use of antiviral medications for prevention may be particularly important for people at high risk of flu complications who have had a close exposure to someone with novel H1N1 flu.

·         Even if a school is closed for an extended period of time, both children and adults are still susceptible to flu if they have interactions with other people, some of whom may be shedding flu viruses even though they don’t have symptoms.

·         The largest number of novel H1N1 confirmed and probable cases are occurring in people from the ages of 5 to 24, so many of them are school-aged children.

·         Students, faculty, and staff who have flu-like illness should stay home for 7 days after symptoms have started or at least 24 hours after symptoms resolve, whichever is longer, seeking medical care if symptoms are severe.

·         Students, faculty and staff who appear to have flu-like illness or become ill during the school day should be isolated promptly in a room separate from other students and sent home.

·         Any dismissal based on local considerations must be done while working closely with the local or state health departments.

·         Schools and childcare facilities do not need to do extra cleaning (such as washing walls) before children can return. 

·         Schools can help teach students and staff how to reduce the spread of novel H1N1 flu through hand hygiene and cough etiquette.

 

·         Washing hands or use of alcohol-based gels in schools or at home can offer protection.

 

·         People at high risk for flu associated complications who have had close contact with someone sick with flu should consider talking to their health care provider about influenza antiviral medications.