HILL AIR FORCE BASE, Utah — Flu season is rapidly approaching here in Utah, and one of Utah’s largest single-site employer is encouraging all employees and on base personnel to get the flu shot.

As in earlier years, both national and regional experts mention the preparation and formulation of vaccines used in each country. Recommendations for the preparation of northern hemisphere influenza vaccines are made by the Food and Drug Administration, which has regulatory authority over vaccines in the United States.

The FDA recommends that routine annual influenza vaccination of all persons 6 months and older without contraindications continues. Persons with a history of egg allergy of any severity may receive any licensed, recommended, and age-correct influenza vaccine (IIV, RIV4, or LAIV4).

The IIV and RIV4 vaccine have been previously suggested. It is recommended that vaccinations should be offered by the end of October. However, vaccination should occur before onset of influenza activity in the community.

According to the World Health Organization, in the U.S. localized outbreaks that indicate the start of seasonal influenza activity can occur as early as October.

However, in 75 percent of influenza seasons from 1982-83 through 2017-18, peak influenza activity, which often is close to the midpoint of influenza activity for the season, has not occurred until January or later. In 58 percent of seasons, the peak was in February or later.

It should be noted vaccinations obtained to prevent influenza are particularly important for persons at increased risk for severe impediments from influenza.

Typically, the U.S. sees influenza strains similar to those circulating in the southern hemisphere, but circulating flu viruses can mutate and change all throughout the year, making it easier for the virus to infect people who have not been vaccinated.

Both trivalent (3 component) and quadrivalent (4 component) influenza vaccines will be available in the U.S. The 2018–19 U.S. influenza vaccines will contain hemagglutinin derived from the following:

• an A/Michigan/45/2015 (H1N1)pdm09–like virus,

• an A/Singapore/INFIMH-16-0019/2016 (H3N2)–like virus, and

• a B/Colorado/06/2017–like virus (Victoria lineage)

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.

What’s new this flu season?

• Flu vaccines have been updated to better match circulating viruses.

• For the 2018-19 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. There is a precaution against the use of LAIV for people with certain underlying medical conditions. All LAIV will be quadrivalent, or 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 and older to 6 months and older after the annual recommendations were published last season to be consistent with FDA-approved labeling.

• The age recommendation for Afluria Quadrivalent was changed from 18 years and older to 5 years and older after the annual recommendations were published last season to be consistent with FDA-approved labeling.

Why is the nasal spray being recommended as an option this year when it has been shown to not be effective in past flu seasons?

While observational data from 2010-11 through 2015-16 flu seasons indicate that LAIV was not effective among 2 through 17-year-olds against H1N1pdm09 influenza viruses in the U.S., LAIV was effective against influenza B viruses, and was similarly effective to inactivated influenza vaccines against H3N2 viruses. Some data suggest that the new H1N1 vaccine virus included in the new LAIV vaccines will have improved effectiveness against circulating H1N1 viruses; however, no published effectiveness estimates are available yet.

What viruses will the 2018-19 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 2018-19, 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.

The FDA licensed a seasonal influenza vaccine containing adjuvant for adults 65 years and older. An adjuvant is an ingredient added to a vaccine to create a stronger immune response to vaccination. FLUAD was licensed in November 2015 and will be available during the 2018-19 flu season. It contains the MF59 adjuvant, an oil-in-water emulsion of squalene oil. FLUAD is the first adjuvanted seasonal flu vaccine marketed in the U.S.

Can I get vaccinated and still get the flu?

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

• You may be exposed to a flu 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. Antibodies that provide protection develop in the body about 2 weeks after vaccination.

• You may be exposed to a flu virus that is not included in the seasonal flu vaccine. There are many different flu viruses that circulate every year. A flu vaccine is made to protect against the three or four flu viruses that research suggests will be most common.

• Protection provided by a flu vaccination can vary widely, based in part on health and age factors of the person getting vaccinated. In general, a flu vaccine works best among healthy younger adults and older children. Some older people and people with certain chronic illnesses may develop less immunity after vaccination. Flu vaccination is not a perfect tool, but it is the best way to protect against flu infection.

What is the recommended composition of influenza virus vaccines for use in the 2018-19 northern hemisphere influenza season?

It is recommended that quadrivalent vaccines for use in the 2018-19 northern hemisphere influenza season contain the following:

• an A/Michigan/45/2015 (H1N1)pdm09-like virus;

• an A/Singapore/INFIMH-16-0019/2016 (H3N2)-like virus;

• a B/Colorado/06/2017-like virus (B/Victoria/2/87 lineage); and

• a B/Phuket/3073/2013-like virus (B/Yamagata/16/88 lineage).

It is recommended that the influenza B virus component of trivalent vaccines for use in the 2018-19 northern hemisphere influenza season be a B/Colorado/06/2017-like virus of the B/Victoria/2/87-lineage.