by Loren G. Edelstein | February 16, 2018
This season's flu vaccine is about 36 percent effective overall, according to interim statistics published today by the Centers for Disease Control and Prevention, with better results for children. But while it is less effective than in past years, the vaccine is performing better than initially feared.

The flu vaccine protects against three strains of flu, and the level of effectiveness varies by strain. Two are A strains, which affect animals and humans: H3N2 (the predominant strain now circulating) and H1N1 ("swine flu"). It also protects against influenza B. Effectiveness against H3N2 is typically the lowest; this year's shot is estimated to be 25 percent effective against H3N2, while it is 67 percent effective against H1N1 and 42 percent against influenza B.

But for children of ages 6 months to 8 years, the vaccine has proven to be more effective overall, at a rate of 59 percent.

Anne Schuchat, M.D. (RADM, USPHS), acting director of the CDC, recently briefed the media on the current status of flu in the U.S. and effective ways to contain and treat the illness. Following are highlights from the CDC's Feb. 9 conference call.
 
How bad is this flu season?
Unfortunately, it looks like this flu season continues to be particularly challenging. Influenza activity is still on the rise overall. In fact, we may be on track to beat some recent records.

Before getting into the specifics, I want to recognize that we know this issue is personal to so many Americans, and that there is a lot of fear and alarm about this flu season. There have been far too many heart-wrenching stories in recent weeks about families who have lost loved ones to influenza. And unfortunately, this week's report reveals more somber news, with an additional 10 flu-related pediatric deaths for this season. That means we have now received reports for 63 children who have died of the flu so far this season.

Flu is incredibly difficult to predict, and we don't know if we've hit the peak yet. In the past five seasons, influenza-like illness has been elevated for between 11 and 20 weeks, so we could potentially see up to eight more weeks of activity. Based on the latest data, levels of influenza-like illness across the country are now as high as we observed at the peak of the 2009 H1N1 pandemic. That's a signal of how very intense this flu season has been.

What is the rate of hospitalizations due to the flu?
In terms of hospitalizations, we have not just crossed a line, but we're quite a bit higher than the record 2014-2015 season. The proportion of deaths attributed to pneumonia and influenza is 10.1 percent this week. That means one out of 10 people who died in the week that has passed died from influenza or pneumonia. Influenza A H3N2 viruses continue to dominate this season, and these viruses are often linked to more severe illness, especially among children and people age 65 and older.

What strains are the most prevalent now, and where?
We are seeing an increasing proportion of B viruses circulating, as well as a smaller increase in the proportion of H1N1 viruses. Last week, B strains made up 30 percent of the tested viruses. We actually usually see better vaccine protection against these. This week, 48 states are still reporting widespread geographic influenza activity. Oregon and Hawaii are reporting regional or less widespread activity. Last week we reported that part of the West Coast is seeing declines in flu activity. This is still true for H3N2 viruses, but some Western states are beginning to see an increase in influenza B activity now. It's not uncommon for there to be second waves of influenza B activity during an influenza season. In past seasons similar to this one, an estimated 34 million Americans have gotten sick with flu.

How can people reduce their risk of getting sick?
Because of the ongoing intensity of the flu season and the increasing circulation of influenza B and H1N1, we continue to recommend vaccination even this late in the season. I know there are ongoing concerns about whether the flu vaccine is effective this year, and it's true that flu vaccines often have lower effectiveness against H3N2 viruses. However, some protection is better than none. Plus, the vaccine's effectiveness against other flu viruses, like B and H1N1, is better.

I also want to reiterate the importance of the pneumococcal pneumonia vaccine. Flu can make people more vulnerable to secondary infections like bacterial pneumonia, so we recommend people 65 and over get the pneumococcal pneumonia vaccine. Most children have already been vaccinated against pneumococcal disease from shots they got when they were infants or toddlers. While we need to get flu vaccines every year because the viruses keep changing, the pneumococcal vaccines are more long-lasting.

What other preventive measures do you recommend?

You can help reduce the spread of flu through simple good health habits, like staying away from people who are sick, frequently washing your hands and covering your cough and sneeze. For those who are already sick, please stay home from work or school. That is such an important recommendation to follow. Otherwise you run the risk of spreading the virus to others - and what may be mild symptoms to you could be deadly to someone else.

The CDC also offers specific advice for preventing flu at meetings and events.

Should people who have flu symptoms take antivirals like Tamiflu?
Antiviral medications are an important tool for treatment. It's important to remember that most people with flu will feel ill and should stay home from school or work, but most of them won't need to see a doctor, won't need to be tested and won't need to get antiviral drugs. Antiviral medicines are recommended for people who are very sick with flu, or people who are at high risk of serious flu complications who develop flu symptoms. People at higher risk of developing serious flu complications include those who are very young, very old, pregnant women and people with conditions like heart or lung disease. 

Clinicians don't have to wait for confirmatory flu testing and should begin treatment with antiviral drugs immediately if they suspect flu in a severely ill or high-risk patient. There is a lot of flu out there right now. If it looks like flu, it probably is. Antivirals could mean the difference between a milder illness and a hospital stay or worse. And they work better if they are started earlier.

Is there still a shortage of antivirals?
There has been a lot of interest in the availability of antiviral drugs. Although we know there have been spot shortages in some places experiencing high influenza activity, manufacturers say there is product available. For patients, that might mean calling more than one pharmacy to fill a prescription. Staff here at CDC have been working closely with the commercial supply chain and pharmacies to address gaps in the market and increase access to brand product when the antiviral generics aren't available. We appreciate the efforts of suppliers, pharmacies and insurers to try to smooth things out for consumers.

Without being tested, how can someone determine if they have a cold or flu?
It's important to understand that the flu isn't just sniffles and a cough. The more severe symptoms include a persistent high fever, difficulty breathing or shortness of breath, a rapid heartbeat and significant tiredness or confusion. Another severe symptom is this: You start to get better, and then suddenly you feel much worse. That could indicate a secondary bacterial pneumonia, and you should seek medical attention immediately if that's happening.

What's the best advice for parents who are concerned about their kids?
It can be difficult to assess symptoms, especially in young children. Also, about half of the cases of hospitalizations for influenza in children have occurred in previously healthy kids with no underlying conditions. That's why we strongly recommend parents get their children vaccinated each year against the flu. It's important for parents to speak with a health-care provider at the first sign of trouble.

Flu continues to be a priority for CDC, and we are working 24/7 to protect Americans from it. This is a difficult season, and we can't predict how much longer the intense flu activity will last. But if we all stay vigilant and take steps to fight the flu, we can help reduce the risk of getting it - and transmitting it.