by Loren G. Edelstein | January 17, 2018
The U.S. is in the midst of a "very active" flu season, according to the latest statistics from the Centers for Disease Control and Prevention. Last Friday, CDC officials briefed the media on the prevalence of the virus, the effectiveness of current vaccines and the role of antiviral medications as treatment. The following has been excerpted from that teleconference, during which CDC director Brenda Fitzgerald and Dan Jernigan, director of the influenza division in the CDC's National Center for Immunization and Respiratory Diseases, spoke.

"We are currently in the midst of a very active flu season, with much of the country experiencing widespread and intense flu activity," said Fitzgerald in introductory remarks. "Many of you may have been directly impacted by this. You may have been sick with the flu yourself or caring for loved ones who are sick. I also know that many of you may have received the flu vaccine this season, but you got sick anyway, or you tried to fill a prescription for medicines to treat the flu, and it was difficult to do. We are here today to discuss these issues and our latest information with you.

"So far this season, influenza A, H3N2, has been the most common form of influenza. These viruses are often linked to more severe illness, especially among children and people age 65 and older. When H3 viruses are predominant, we tend to have a worse flu season with more hospitalizations and more deaths. While our surveillance systems show that nationally the flu season may be peaking now, we know from past experience that it will take many more weeks for flu activity to truly slow down.

"We also know that you can reduce your risk of getting the flu through everyday good health habits like covering your mouth when you cough and frequently washing your hands. You need, of course, to limit contact with others who might be sick and, if possible, stay home when you are sick to help prevent the spread of germs and respiratory illnesses like the flu. These are the most important measures that we all should be doing.

"We also continue to recommend the flu vaccine. While our flu vaccines are far from perfect, they are the best way to prevent getting sick from the flu, and it is not too late to get one. As of this last month, manufacturers reported that they have shipped more than 151 million doses of flu vaccines, so it should be readily available.

"Someday, of course, we hope to have a universal flu vaccine, one that attacks all influenza type viruses and provides protection that lasts for years. But until that day arrives, we will continue to improve the vaccines that we have and find ways and tools to help Americans reduce their risk of getting sick.

"Now, I'll turn it over to Dr. Jernigan, director of the influenza division in CDC's National Center for Immunization and Respiratory Diseases, who will talk about the activities we're seeing this season."

The following has been excerpted Dr. Jernigan's remarks. The full transcript of the media conference is available here.

Where is the flu prevalent?
I think the simplest way to describe it is that flu is everywhere in the U.S. right now. There's lots of flu in lots of places. Our team that does this kind of surveillance study has been doing this particular thing for 13 years, and this is the first year we had the entire continental U.S. be the same color on the graph, meaning there's widespread activity in all of the continental U.S. at this point. It is in a lot of places and causing a lot of flu.

How bad is it?
The season has started early, and it's probably peaking right about now. There is a rapid rise in the numbers of people being hospitalized with laboratory-confirmed flu. In terms of the numbers, this week in the FluView we'll report there have been 22.7 hospitalizations per 100,000 people in the United States. That's up from 13.7 last week, so that's almost doubling in terms of the numbers, just in the last week.

Who is most at risk?
If you were to look at who is being hospitalized, clearly, the highest rates are among those over age 65 and even for age 50-64, in that sort of baby boomer generation. They are seeing high numbers, and they are increasing over last week. The other area that we are, of course, following closely is cases in children younger than 5 years, which have almost doubled in the last week. The people that we see affected with H3N2, that is the very young, the very old and those with underlying conditions, clearly are showing up in the hospitalization data as being the most affected.

Are people dying from flu?
We've been monitoring mortality. We're sad to report this week that there are an additional seven flu-associated pediatric deaths, bringing the number of pediatric deaths reported so far to the CDC to 20. In addition, there have been reports of young, otherwise healthy adults admitted to hospitals with very progressive influenza disease, who have died. It's a reminder that flu, while causing mild disease in a lot of people, can also cause severe disease and death in others.

How does this flu season compare to prior years?
Right now, it is looking like our season seems to be tracking somewhat worse than 2012-2013, perhaps not as bad as 2014-2015. We actually published recently a paper looking at how to characterize influenza seasons into levels of severity, and over the last 13 years there have only been two seasons where we have what's called high severity. The first was 2003-2004. The other was 2014-2015; both of those were H3N2-predominant years. Whether we reach that level this season, we don't know, but we think it's somewhere between those two, 2012-2013 and 2014-2015.

How much longer will flu season last?
We're currently in the seventh season [that has been tracked]. If you look at seasons like this one, there are at least 11 to 13 more weeks of influenza to go. In addition, other strains of the flu are expected to show up and to be a major cause of disease. We always know that B viruses, which the vaccine also covers, will be showing up later in the season. That's another reason why it's good to go ahead and get vaccinated now if you have not gotten vaccinated.

What about "swine flu"?
We are seeing H1N1, or swine flu, starting to show up in states that have already had H3 activity, so it's possible we may have a pretty robust season, not just with H3, but with the others as well.

How effective are antiviral drugs like Tamiflu?
While influenza vaccination is the best way to prevent influenza infection, antiviral drugs have been approved and are recommended to treat influenza illness. These drugs can lessen the symptoms and shorten the duration of illness, and studies have shown that they prevent serious flu complications. Antiviral drugs work better the earlier you begin to take them, so getting them as quickly as possible is best.  

Should everyone who gets the flu take antiviral drugs?
During influenza epidemics, with widespread and intense flu activity, flu antivirals can reduce the burden of illness in a community. Most people who get the flu have mild illness and they don't need medical care or antiviral drugs; however, some people are more likely to get very sick from flu. CDC recommends that people who are very sick, or people with flu symptoms who are high-risk for serious flu complications should be treated as soon as possible with flu antiviral drugs. That means people 65 and older. It means young children. It means people with chronic conditions like diabetes, heart disease or asthma. It means pregnant women and others more vulnerable to serious flu illness. Clinicians should not wait for confirmed testing, but they should begin treatment if they suspect flu in a severely ill or high-risk patient.

Are these drugs readily available?
There's been a lot of interest in antiviral drug supply. The CDC has been in regular contact with influenza antiviral manufacturers regarding supply and other issues. While the total reported national supply of influenza antiviral drugs should be sufficient to meet this high seasonal demand, some manufacturers are reporting delays in filling orders, and the CDC is aware of spot shortages of antiviral drugs in some places that have high influenza activity. There are a number of new manufacturers on the market because of the new formulations, and generic formulations are available. It may be that pharmacies need to check with different manufacturers to make sure they can get those drugs. We are working closely with the manufacturers to address any existing gaps in the market.

How effective is the flu vaccine?
Vaccination is our main tool to prevent influenza infection, and the CDC recommends that vaccination efforts continue as long as influenza viruses are circulating. It takes about two weeks for protection from vaccination to set in, but, as I said, we have a lot of flu season to get through still. We will see other flu viruses start to circulate later during the flu season, and most flu vaccines protect against all four of those circulating viruses. The B viruses are still to really show up and take off. So, getting a vaccine would help cover them as well.

Is the flu vaccine still readily available?
The manufacturers are reporting that they've shipped more than 151 million doses of flu vaccine, so there should be product available to folks. One tool you can use is to go to the CDC website and look up the vaccine finder. This is a tool you can put your zip code in, and it will help find where there are vaccines near you.

How effective is the flu vaccine this season?
In addition to being associated with increased severity, H3N2 seasons also are associated with vaccine effectiveness that is lower than what we usually see against H1NI or influenza B viruses. The preliminary vaccine-effectiveness data from studies ongoing this season will not be available until at least mid-February. We're still enrolling patients in our study sites, and at this time we're using laboratory data to try to suggest how well our vaccines may work. Our information so far suggests that vaccine effectiveness against the predominant H3 viruses will probably be somewhere around what we saw in the 2016-2017 season, which was in the 30 percent range. While this is better than the 10 percent that has been reported from Australia in one study, it still leaves a lot to be desired, and we're very well aware we need to have better flu vaccines. There are many steps that have been taken in the past few years to make our vaccines supply more robust and more effective.

What other precautions should people take to avoid getting sick?

Do not forget the everyday common-sense behaviors that your mother taught you: Stay away from people who are sick, stay home from work or school if you get sick, cover your cough and wash your hands often. These actions can reduce the spread of respiratory illnesses like flu in the community.

Click here for additional information, including statistics and maps.