What’s new this flu season?
A few things are new this season:
- Flu vaccines have been updated to better match circulating viruses [the B/Victoria component was changed and the influenza A(H3N2) component was updated].
- For the 2018-2019 season, the nasal spray flu vaccine (live attenuated influenza vaccine or “LAIV”) is again a recommended option for influenza vaccination of persons for whom it is otherwise appropriate. The nasal spray is approved for use in non-pregnant individuals, 2 years through 49 years of age. People with some medical conditions should not receive the nasal spray flu vaccine. All LAIV will be quadrivalent (four-component).
- Most regular-dose egg-based flu shots will be quadrivalent.
- All recombinant vaccine will be quadrivalent. (No trivalent recombinant vaccine will be available this season.)
- Cell-grown flu vaccine will be quadrivalent. For this vaccine, the influenza A(H3N2) and both influenza B reference viruses will be cell-derived, and the influenza A(H1N1) will be egg-derived. All these reference viruses will be grown in cells to produce the components of Flucelvax.
- No intradermal flu vaccine will be available.
- The age recommendation for “Fluarix Quadrivalent” was changed from 3 years old and older to 6 months and older after the annual recommendations were published last season to be consistent with Food and Drug Administration (FDA)-approved labeling.
- The age recommendation for Afluria Quadrivalent was changed from 18 years old and older to 5 years old and older after the annual recommendations were published last season to be consistent with Food and Drug Administration (FDA)-approved labeling.
What flu vaccines are recommended this season?
For the 2018-2019 flu season, providers may choose to administer any licensed, age-appropriate flu vaccine (IIV, RIV4, or LAIV4).
- Standard dose flu shots. These are given into the muscle. They are usually given with a needle, but two (Afluria and Afluria Quadrivalent) can be given to some people (those aged 18 through 64 years) with a jet injector.
- High-dose shots for older people.
- Shots made with adjuvant for older people.
- Shots made with virus grown in cell culture.
- Shots made using a vaccine production technology (recombinant vaccine) that does not require the use of flu virus.
- Live attenuated influenza vaccine (LAIV) – or the nasal spray vaccine – is also an option for use during the 2018-2019 season for persons whom it is otherwise appropriate.
There is a table showing all flu vaccines that are FDA-approved for use in the United States during the 2018-2019 season.
What viruses will the 2018-2019 flu vaccines protect against?
There are many different flu viruses and they are constantly changing. The composition of U.S. flu vaccines is reviewed annually and updated as needed to match circulating flu viruses. Flu vaccines protect against the three or four viruses (depending on vaccine) that research suggests will be most common. For 2018-2019, trivalent (three-component) vaccines are recommended to contain:
- A/Michigan/45/2015 (H1N1)pdm09-like virus
- A/Singapore/INFIMH-16-0019/2016 A(H3N2)-like virus (updated)
- B/Colorado/06/2017-like (Victoria lineage) virus (updated)
Quadrivalent (four-component) vaccines, which protect against a second lineage of B viruses, are recommended to contain:
- The three recommended viruses above, plus B/Phuket/3073/2013-like (Yamagata lineage) virus
When should I get vaccinated?
You should get a flu vaccine before flu begins spreading in your community. It takes about two weeks after vaccination for antibodies that protect against flu to develop in the body, so make plans to get vaccinated early in fall, before flu season begins. CDC recommends that people get a flu vaccine by the end of October. Getting vaccinated later, however, can still be beneficial and vaccination should continue to be offered throughout flu season, even into January or later.
Children who need two doses of vaccine to be protected should start the vaccination process sooner, because the two doses must be given at least four weeks apart.
Can I get a flu vaccine if I am allergic to eggs?
The recommendations for people with egg allergies are the same as last season.
- People who have experienced only hives after exposure to egg can get any licensed flu vaccine that is otherwise appropriate for their age and health.
- People who have symptoms other than hives after exposure to eggs, such as angioedema, respiratory distress, lightheadedness, or recurrent emesis; or who have needed epinephrine or another emergency medical intervention, can also get any licensed flu vaccine that is otherwise appropriate for their age and health, but the vaccine should be given in a medical setting and be supervised by a health care provider who is able to recognize and manage severe allergic conditions. (Settings include hospitals, clinics, health departments, and physician offices). People with egg allergies no longer have to wait 30 minutes after receiving their vaccine.
Flu Activity
What sort of flu season is expected this year?
It is not possible to predict what this flu season will be like. While flu spreads every year, the timing, severity, and length of the season varies from one season to another.
Will new flu viruses circulate this season?
Flu viruses are constantly changing so it’s not unusual for new flu viruses to appear each year. For more information about how flu viruses change, visit How the Flu Virus Can Change.
Will the United States have a flu epidemic?
The United States experiences annual epidemics of seasonal flu. This time of year is called “flu season.” In the United States, flu viruses are most common during the fall and winter months. Influenza activity often begins to increase in October and November. Most of the time flu activity peaks between December and February, and it can last as late as May. CDC monitors certain key flu indicators (for example, outpatient visits of influenza-like illness (ILI), the results of laboratory testing and reports of flu hospitalizations and deaths). When these indicators rise and remain elevated for a number of consecutive weeks, “flu season” is said to have begun. Usually ILI increases first, followed by an increase in flu-associated hospitalizations, which is then followed by increases in flu-associated deaths.
- For the most current influenza surveillance information, please see FluView at Weekly U.S. Influenza Surveillance Report.
- When will flu activity begin and when will it peak?
- The timing of flu is unpredictable and can vary in different parts of the country and from season to season. Seasonal flu viruses can be detected year-round; however, seasonal flu activity often begins as early as October and November and can continue to occur as late as May. Flu activity most commonly peaks in the United States between December and February.
How many people get sick with flu every year?
The exact number of flu illnesses that occur each season is not known because flu is not a reportable disease and not everyone who gets sick with flu seeks medical care or gets tested. CDC conducts surveillance of flu related illness through the Outpatient Influenza-like Illness Surveillance Network (ILINet) and FluSurv-Net (see more information on FluSurv-Net in next question). ILINet collects information on outpatient illness, and FluSurv-Net collects information on hospitalizations. For more information, see CDC’s Overview of Influenza Surviellance in the United States.
Because the ILINet systems does not capture all influenza-related illness in the United States, CDC uses mathematical modeling in combination with data from traditional flu surveillance systems to estimate the true burden of flu illness in the United States, including total flu cases. CDC estimates that flu has resulted in between 9.2 million and 35.6 million illnesses each year in the United States. For more information on these estimates, see CDC’s Disease Burden of Influenza page.
How many people are hospitalized from flu every year?
CDC estimates the total number of flu-associated hospitalizations in the United States. CDC’s flu surveillance system FluSurv-NET, monitors rates of lab confirmed flu-associated hospitalizations in about 9% of the U.S. population, and it collects information only on hospitalizations that had a positive flu test. We know that not everyone with an influenza related hospitalization will be captured in this system because not everyone gets a flu test and those that do may not have a positive result if many days have passed since they first became sick. That is why CDC also uses mathematical modeling to fill in the picture of the disease burden. Since 2010, CDC estimates that flu has resulted in between 140,000 and 710,000 hospitalizations each year. For more information, see CDC’s Disease Burden of Influenza page.
How many people die from flu each year?
While flu deaths in children are reported to CDC, flu deaths in adults are not nationally notifiable. In order to monitor influenza related deaths in all age groups, CDC tracks pneumonia and influenza (P&I)–attributed deaths through the National Center for Health Statistics (NCHS) Mortality Reporting System. This system tracks the proportion of death certificates processed that list pneumonia or influenza as the underlying or contributing cause of death. This system provides an overall indication of whether flu-associated deaths are elevated, but does not provide an exact number of how many people died from flu. For more information, see Overview of Influenza Surveillance in the United States, “Mortality Surveillance.”
As it does for the numbers of flu cases, doctor’s visits and hospitalizations, CDC also estimates deaths in the United States using mathematical modeling. CDC estimates that from 2010-2011 to 2013-2014, influenza-associated deaths in the United States ranged from a low of 12,000 (during 2011-2012) to a high of 56,000 (during 2012-2013). Death certificate data and weekly influenza virus surveillance information were used to estimate how many flu-related deaths occurred among people whose underlying cause of death on their death certificate included respiratory or circulatory causes. For more information, see Estimating Seasonal Influenza-Associated Deaths in the United States and CDC’s Disease Burden of Influenza page.
Sources:
Centers for Disease Control and Prevention - https://www.cdc.gov/flu/about/season/flu-season-2018-2019.htm
National Center for Immunization and Respiratory Diseases (NCIRD) - http://www.cdc.gov/ncird/index.html
