Is vaccine still available?

Flu vaccine is produced by private manufacturers, so availability depends on when production is completed. Information about the number of seasonal influenza vaccine doses distributed this season is available at Seasonal Influenza Vaccine & Total Doses Distributed.

In May and September, 2012, influenza vaccine manufacturers originally projected about 135 million doses would be available for the U.S. market during the 2012-2013 season. Recent updates from manufacturers to CDC indicate that more doses of flu vaccine were actually produced, totaling 145 million doses. As of January 4, 2013, more than 128 million doses had been distributed. (During 2011-2012, 132.8 million doses of flu vaccine were distributed in the United States.)

At this time, some vaccine providers may have exhausted their vaccine supplies, while others may have remaining supplies of vaccine. People seeking vaccination may need to call more than one provider to locate vaccine. The flu vaccine locator may be helpful.

Does CDC recommend prioritizing remaining supplies of flu vaccine?

No, CDC does not have a recommendation to prioritize remaining supplies of flu vaccine at this time. CDC continues to recommend influenza vaccination for all people 6 months and older. It also continues to be especially important that people at high risk of influenza complications get vaccinated, including pregnant women, children under 5 years but especially younger than 2 years, older adults 65 years and older, and people with chronic conditions like asthma, diabetes, and heart disease.


Are there supply concerns with antiviral drugs this season?

On January 10, 2013, the U.S. Food and Drug Administration (FDA) released information indicating there may currently be intermittent shortages of Oseltamivir Phosphate (Tamiflu) for Oral Suspension (6mg/mL 60 mL), due to increased demand for the drug. This is the pediatric suspension (liquid). FDA has instructions for pharmacists on how to compound an oral suspension from Tamiflu 75 mg (adult) capsules. These instructions provide for an alternative oral suspension when commercially manufactured oral suspension formulation is not readily available.

Should I still get vaccinated even if I have already gotten sick with the flu?

Yes. There are a couple of reasons why you should be vaccinated even if you have already been sick with a flu-like illness this season. First, it’s possible that your illness was not caused by an influenza virus. There are other respiratory viruses circulating along with flu that can have similar flu symptoms. The only way to know for sure that a flu virus is making you sick is to have a sample taken and tested in a laboratory. Second, even if you were sick with one influenza virus, the seasonal flu vaccine protects against three types of flu viruses that research suggests will be most common. This means the vaccine can offer protection against other influenza viruses you haven’t been exposed to yet.


Can I get vaccinated and still get influenza?

Yes. It’s possible to get sick with influenza even if you have been vaccinated (although you won’t know for sure unless you get a positive influenza test). This is possible for the following reasons:

•You may be exposed to an influenza virus shortly before getting vaccinated or during the period that it takes the body to gain protection after getting vaccinated. This exposure may result in you becoming ill with flu before the vaccine begins to protect you. (About 2 weeks after vaccination, antibodies that provide protection develop in the body.)

•You may be exposed to an influenza virus that is not included in the seasonal flu vaccine. There are many different influenza viruses that circulate every year. The composition of the flu shot is reviewed each season and updated if needed to protect against the three viruses that research suggests will be most common. Characterization of influenza viruses collected this season in the United States indicates that most circulating viruses are like the vaccine viruses; however, there is a smaller percentage of viruses that the vaccine would not be expected to protect against.

•Unfortunately, some people can get infected with an influenza virus the flu vaccine is designed to protect against despite getting vaccinated. Protection provided by influenza vaccination can vary widely, based in part on health and age factors of the person getting vaccinated. In general, the flu vaccine works best among young healthy adults and older children. Some older people and people with certain chronic illnesses may develop less immunity after vaccination. While vaccination offers the best protection against influenza infection, it's still possible that some people may become ill after being vaccinated. Influenza vaccination is not a perfect tool, but it is the best tool currently at our disposal to prevent influenza.

Is this season's vaccine a good match for circulating viruses?

Over the course of a flu season, CDC studies samples of flu viruses circulating during that season to evaluate how close a match there is between viruses used to make the vaccine and circulating viruses. Data are published in the weekly FluView.

As of the first week in January 2013, most (91%) of the influenza viruses that have been analyzed at CDC are like the viruses included in the 2012-2013 influenza vaccine. The match between the vaccine virus and circulating viruses is one factor that impacts how well the vaccine works.

What flu viruses does the vaccine protect against?

Flu vaccines are designed to protect against the three influenza viruses that research indicates will be the most common during the upcoming season. Three kinds of influenza viruses commonly circulate among people today: influenza B viruses, influenza A (H1N1) viruses, and influenza A (H3N2) viruses. Each year, one flu virus of each kind is used to produce seasonal influenza vaccine.

Note: The H1N1 virus is the same as the H1N1 virus that was included in the 2011-2012 vaccine, but the influenza H3N2 and B vaccine viruses are different..


In what years was there a good match between the vaccine and the circulating viruses?

In recent years the match between the vaccine viruses and those identified during the flu season has usually been good. In 18 of the last 22 U.S. influenza seasons the viruses in the influenza vaccine have been well matched to the predominant circulating viruses. Since 1990, there has only been one season (1997-98) when there was very low cross-reaction between the viruses in the seasonal vaccine and the predominant circulating virus, and three seasons (1992-93, 2003-04, and 2007-08) when there was low cross-reaction.

It's not possible to predict with certainty which flu viruses will predominate during a given season. Flu viruses are constantly changing (called “antigenic drift”) – they can change from one season to the next or they can even change within the course of one flu season. Experts must pick which viruses to include in the vaccine many months in advance in order for vaccine to be produced and delivered on time. (For more information about the vaccine virus selection process visit Selecting the Viruses in the Influenza (Flu) Vaccine.) Because of these factors, there is always the possibility of a less than optimal match between circulating viruses and the viruses in the vaccine. CDC analyzes influenza viruses that are circulating each season to see whether they are like the viruses included in that season's vaccine.


Can the vaccine provide protection even if the vaccine is not a "good" match?

Yes, antibodies made in response to vaccination with one flu virus can sometimes provide protection against different but related viruses. A less than ideal match may result in reduced vaccine effectiveness against the virus that is different from what is in the vaccine, but it can still provide some protection against influenza illness.

In addition, it's important to remember that the flu vaccine contains three virus viruses so that even when there is a less than ideal match or lower effectiveness against one virus, the vaccine may protect against the other viruses.

For these reasons, even during seasons when there is a less than ideal match, CDC continues to recommend flu vaccination. This is particularly important for people at high risk for serious flu complications, and their close contacts.


I have heard of people who don’t get vaccinated against influenza in September or October because they want it to “last” through the entire influenza season. Should people wait until later in the influenza season to be vaccinated?

CDC recommends that influenza vaccination begin as soon as vaccine becomes available in the community and continue throughout the flu season. It takes about two weeks after vaccination for antibodies to develop in the body that provide protection against influenza, and influenza seasons can begin as early as October. Therefore, CDC recommends that vaccination begin as soon as vaccine becomes available to ensure that as many people as possible are protected before flu season begins.


Were there any new recommendations for the 2012-2013 influenza season?

No substantive changes to the Advisory Committee on Immunization Practices (ACIP) influenza vaccine recommendations were made for the 2012-2013 influenza season.

Who should get vaccinated?

Everyone who is at least 6 months of age should get a flu vaccine this season. It’s especially important for some people to get vaccinated. Those people include the following:

•People who are at high risk of developing serious complications like pneumonia if they get sick with the flu ◦This includes

■People who have certain medical conditions including asthma, diabetes, and chronic lung disease.

■Pregnant women.

■People 65 years and older.

•People who live with or care for others who are high risk of developing serious complications ◦This includes household contacts and caregivers of people with certain medical conditions including asthma, diabetes, and chronic lung disease.

Who should take antiviral drugs this season?

It’s very important that antiviral drugs be used early to treat people who are very sick with the flu (for example people who are in the hospital) and people who are sick with the flu and have a greater chance of getting serious flu complications, either because of their age or because they have a high risk medical condition. Other people also may be treated with antiviral drugs by their doctor this season. Most otherwise-healthy people who get the flu, however, do not need to be treated with antiviral drugs.


What is antiviral resistance?

Antiviral resistance means that a virus has changed in such a way that the antiviral drug is less effective in treating or preventing illness. Samples of viruses collected from around the United States and worldwide are studied to determine if they are resistant to any of the FDA-approved influenza antiviral drugs.


What is CDC doing to monitor antiviral resistance in the United States during the 2012-13 season?

CDC routinely collects viruses through a domestic and global surveillance system to monitor for changes in influenza viruses. Additionally, CDC is working with the state public health departments and the World Health Organization to collect additional information on antiviral resistance in the United States and worldwide. 

Reactions to nasal spray flu vaccine:

People also may have mild reactions to the nasal spray vaccine. Some children and young adults 2-17 years of age have reported experiencing mild reactions after receiving nasal spray flu vaccine, including runny nose, nasal congestion or cough, chills, tiredness/weakness, sore throat and headache. Some adults 18-49 years of age have reported runny nose or nasal congestion, cough, chills, tiredness/weakness, sore throat and headache. These side effects are mild and short-lasting, especially when compared to symptoms of seasonal influenza infection.

What about serious reactions to flu vaccine?

Serious allergic reactions to flu vaccines are very rare. If they do occur, it is usually within a few minutes to a few hours after the vaccination. While these reactions can be life-threatening, effective treatments are available.

What about people who get a seasonal flu vaccine and still get sick with flu-like symptoms?

There are several reasons why someone might get a flu-like illness, even after they have been vaccinated against flu.

1.One reason is that some people can become ill from other respiratory viruses besides flu such as rhinoviruses, which are associated with the common cold, cause symptoms similar to flu, and also spread and cause illness during the flu season. The flu vaccine only protects against influenza viruses, not other viruses.

2.Another explanation is that it is possible to be exposed to influenza viruses, which cause the flu, shortly before getting vaccinated or during the two-week period after vaccination that it takes the body to develop immune protection. This exposure may result in a person becoming ill with flu before protection from the vaccine takes effect.

3.A third reason why some people may experience flu like symptoms despite getting vaccinated is that they may have been exposed to an influenza virus that is very different from the viruses the vaccine is designed to protect against. The ability of a flu vaccine to protect a person depends largely on the similarity or “match” between the viruses selected to make the vaccine and those spreading and causing illness. There are many different influenza viruses that spread and cause illness among people. For more information, see Influenza (Flu) Viruses.

4.The final explanation for experiencing flu-like symptoms after vaccination is that unfortunately, the flu vaccine doesn’t always provide adequate protection against the flu. This is more likely to occur among people that have weakened immune systems or people age 65 and older.

Misconceptions about the timing of seasonal influenza vaccination

Should I wait to get vaccinated so that my immunity lasts through the end of the season?

No. CDC recommends that influenza vaccination begin as soon as flu vaccine becomes available and continues throughout the flu season. The flu season is unpredictable, and since it takes about two weeks after vaccination for antibodies to develop in the body that protect against influenza virus infection, it is best that people get vaccinated early so they are protected before influenza begins spreading in their community. While immunity can vary by person, previously published studies suggest that immunity lasts through a full flu season. Although adults 65 and older typically have a reduced immune response to flu vaccination compared with young healthy adults, their immune protection still extends through one flu season. In addition, a review of published studies concluded that no clear evidence exists that immunity declines more rapidly in the elderly. Note: The high-dose vaccine for people aged 65 and older is intended to create a stronger immune response in this age group.

Is it too late to get vaccinated after Thanksgiving (or the end of November)?

No. Vaccination can still be beneficial as long as influenza viruses are circulating. CDC recommends that providers begin to offer influenza vaccination as soon as vaccine becomes available in the fall, but if you have not been vaccinated by Thanksgiving (or the end of November), it can still be protective to get vaccinated in December or later. Influenza is unpredictable and seasons can vary. Seasonal influenza disease usually peaks in January or February most years, but disease can occur as late as May.

Influenza Vaccination Information for Health Care Workers

•CDC, the Advisory Committee on Immunization Practices (ACIP), and the Healthcare Infection Control Practices Advisory Committee (HICPAC) recommend that all U.S. health care workers get vaccinated annually against influenza.

•Health care workers include (but are not limited to) physicians, nurses, nursing assistants, therapists, technicians, emergency medical service personnel, dental personnel, pharmacists, laboratory personnel, autopsy personnel, students and trainees, contractual staff not employed by the health-care facility, and persons (e.g., clerical, dietary, housekeeping, laundry, security, maintenance, administrative, billing, and volunteers) not directly involved in patient care but potentially exposed to infectious agents that can be transmitted to and from health care workers and patients.

 

Why Get Vaccinated?

•Influenza (the flu) can be a serious disease that can lead to hospitalization and sometimes even death. Anyone can get sick from the flu.

•You can get the flu from anyone, including patients and coworkers who are sick with the flu.

•If you get the flu, you can spread it to others even if you don’t feel sick.

•By getting vaccinated, you can help protect yourself, your family at home, and also your patients at work from getting the flu.

 

What Does the Research Say?

•Health care workers who get vaccinated help to reduce the following: ◦transmission of influenza

◦staff illness and absenteeism

◦influenza-related illness and death, especially among people at increased risk for severe influenza illness

•Higher vaccination levels among staff have been associated with a lower risk of nosocomial (hospital-acquired) influenza cases.

•Influenza outbreaks in hospitals and long-term care facilities have been attributed to low influenza vaccination coverage among health care workers in those facilities.

•Higher influenza vaccination levels among health care workers can reduce influenza-related illness, and even deaths, in settings like nursing homes.

Influenza Prevention: Information for Travelers

The risk for exposure to influenza during travel depends somewhat on the time of year and destination.

•In the Northern Hemisphere, the flu season can begin as early as October and can last as late as April or May.

•In the temperate regions of the Southern Hemisphere, influenza activity occurs typically during April--September.

•In the tropics, influenza occurs throughout the year.

•Travelers in the Northern and Southern Hemispheres can be exposed to influenza during months that fall outside of those listed above, especially when traveling as part of large tourist groups (e.g., on cruise ships) that include persons from areas of the world in which influenza viruses are circulating.

 

CDC recommends that everyone 6 months and older get a flu vaccine yearly.

•Everyone 6 months and older should get a flu vaccine yearly, preferably in the fall before the U.S. flu season begins.

People traveling to parts of the world where influenza activity is ongoing, and who have not gotten the vaccine for the current season, should get a flu vaccine to protect themselves while on their trip.

•This is particularly important for people at high risk of flu-related complications.

•The flu vaccine used in the Northern Hemisphere usually protects against the main viruses that have been circulating in other parts of the world.

People should get vaccinated at least two weeks before travel because it takes two weeks for vaccine immunity to develop after vaccination.

•No information is available about the benefits of getting revaccinated before summer travel for those people who already were vaccinated during the preceding fall, so revaccination is not recommended.

•Keep in mind that influenza vaccine manufactured for the upcoming or current season usually expires the following June. After June, flu vaccines are usually not available in the U.S. until the influenza vaccine for the next season is produced and made available sometime in the fall.

•Also, if you receive the previous season’s vaccine before travel during the summer months, that coming fall or winter you should still receive the new flu vaccine.

Avoid close contact with sick people.

Influenza A (H3N2) Variant Virus

Influenza viruses that normally circulate in pigs are called “variant” viruses when they are found in people. Influenza A H3N2 variant viruses (also known as “H3N2v” viruses) with the matrix (M) gene from the 2009 H1N1 pandemic virus were first detected in people in July 2011. The viruses were first identified in U.S. pigs in 2010. From July – December 2011, 12 cases of H3N2v infection were detected in the United States (Indiana, Iowa, Maine, Pennsylvania, and West Virginia). From January to September 2012, 307 cases of H3N2v infection across 11 states were detected. These infections were mostly associated with prolonged exposure to pigs at agricultural fairs. Limited human-to-human spread of this virus has been detected as well (Iowa, West Virginia) but no sustained community spread of H3N2v has been identified at this time. It's possible that sporadic infections and even localized outbreaks among people with this virus will continue to occur. The Centers for Disease Control and Prevention (CDC) continues to monitor this situation closely and will report cases of H3N2v and other variant influenza viruses