Focus on Flu

by Anthony Fiore, MD, MPH, medical epidemiologist for the Influenza Division of the CDC.

What a difference a few weeks makes!

Influenza activity has decreased by all measures from the national perspective, although some communities are still seeing widespread flu, almost all of it 2009 H1N1 flu. This means that fewer people are getting sick, and fewer are getting hospitalized, than we saw in September through November.

Is the virus gone? Certainly not yet. In fact more than 99% of flu viruses isolated in December were still the 2009 H1N1 virus. Furthermore, influenza viruses are predictably unpredictable. Flu will probably continue to circulate through the winter months, caused by either 2009 H1N1 viruses or regular seasonal flu viruses. If the 2009 H1N1 virus behaves like other new flu viruses, it intends to stick around.

The good news is that the supply of 2009 H1N1 vaccine has increased dramatically, and in many areas vaccination is being offered to anyone who wants it. As of December 18 the number of doses available had increased to more than 100 million, and manufacturers project another 10 million to 15 million doses each week through January. In some areas however, public demand among priority groups has stayed high, so not every area has been able to open 2009 H1N1 vaccination up to all-yet. That has happened in part because public interest in getting vaccinated has varied a good bit state-to-state.

We still have a long way to go before everyone who wants to be vaccinated has a chance to. Many people, including many among those who were designated to get the limited doses that were initially available, have not been vaccinated yet. As of early December, an estimated 46 million people (15.3% of the population) had been vaccinated against 2009 H1N1 flu. This represents 28 million adults (13% of the total) and 18 million children (24% of the total) who have received the 2009 H1N1 vaccine.

Now that vaccination has been expanded in many areas to include most or all of the population, let’s review what we know so far about who is most at risk if they get 2009 H1N1 influenza:

1. Infections, including severe infections, among children and young adults continue to be more common than we usually see with seasonal influenza.
2. While people 65 or older are less likely to get flu caused by 2009 H1N1 flu, those that do become infected are at greater risk of having serious complications from their illness. Some outbreaks among older people living in long-term care facilities also have been reported. Sometimes these outbreaks have also involved health care workers in the facility – a reminder that regardless of what population a health care worker provides care for, vaccination is very important.
3. Adults younger than 65 years old who have chronic medical conditions such as asthma, heart disease, or neuromuscular conditions are at higher risk of severe illness. There have been many more deaths among persons aged 18-64 than any other age group, and most of those persons have had one or more chronic condition.
4. Data from several studies suggest that obese people (particularly those who are very obese) are also at increased risk of severe flu complications. This group has not previously been recognized to have a higher risk of severe flu.
5. American Indians/Alaskan Natives also appear to be at higher risk.

It’s not yet clear why the higher risk for severe illness in these last two groups, but possible reasons may include being more likely to also have a chronic medical condition that increases their risk of severe illness, less access to early medical care, or something else unique about this virus for those groups. Regardless of the cause or causes, those who are obese or who are an American Indian or Alaskan Native should get vaccinated as should others recommended for 2009 H1N1 vaccine as vaccine becomes available.

Finally, I want to remind everyone about two other groups of people we have been focusing on since the start of the vaccine campaign: children and pregnant women. For 2009 H1N1 vaccine, children younger than 10 years old need to get 2 doses of vaccine.

No doubt pregnant women and their families are weary of hearing about their need to get vaccinated. But we still are seeing severe illness in pregnant women, and it has been shown that when Mom gets vaccinated both mother and infant benefit. We don’t have a vaccine for children less than 6 months old, so anything that can be done to protect them is important.

Now, with a greater supply of the 2009 H1N1 influenza vaccine, it’s quite likely that you can get vaccinated at your doctor’s office. Or, go to one of the retail pharmacies or your local health department. Some large retail stores now have 2009 H1N1 vaccine also. CDC recommends that anyone who wants to be protected from the 2009 H1N1 virus be vaccinated, regardless of age, as soon as vaccine is available for all in their community. The flu season is not over yet.