Flu season is approaching. Are you ready?
The 2017-2018 flu season was a tough one. More than 170 children under 18 died because of flu. And 2018-2019 could be tough as well, with some of the more virulent strains expected to make an encore appearance.
There is some good news for Repertoire readers and their customers: Plenty of injectable vaccine should be available for 2018-19, and FluMist® Quadrivalent intranasal vaccine returns to the market following a two-year hiatus.
The not-so-good news? Some experts predict that the CDC-recommended formulation for this season’s vaccine may have the same reduced efficacy against the dominant strain of influenza A (H3N2) as last year’s. Even so, the bottom line for healthcare providers and consumers is this: GET THE VACCINE ANYWAY.
“Regarding the efficacy of influenza vaccine, for the last two years, it’s been all over the map,” says Gary LeRoy, M.D., FAAFP, a family physician in Dayton, Ohio, and a member of the board of directors of the American Academy of Family Physicians. “Some say it has been 37, 38 or 40 percent effective, and some say it has been as low as 18 percent effective.
“Still, that’s 17 or 18 percent of individuals who might not experience the morbidity or mortality of flu. And if they do get the flu, even with the reduced efficacy of the vaccine, it won’t be as deadly as if they had not had the vaccine. It blunts the effects of the virus. So we continue to stress the importance of everyone getting the flu vaccine to lessen its severity.”
Unpredictable
“This past flu season was a strong reminder that the flu can be unpredictable,” says Heather Levis Guzzi, director, U.S. product communications, Sanofi Pasteur. “Modern egg-based vaccine production is the most reliable method capable of delivering the volume of safe and effective flu vaccines needed each season.
“Even in years when vaccine effectiveness is lower than we would like, available flu vaccines help prevent a large number of hospitalizations and help protect people from severe, life-threatening illness and complications.” An analysis published in the Proceedings of the National Academy of Sciences estimated that even when flu vaccine efficacy is as low as 20 percent, it can help prevent 130,000 hospitalizations and 62,000 deaths, she says.
For the 2018-2019 season, Sanofi Pasteur expects to produce nearly 70 million doses of flu vaccines, says Guzzi. This year, in addition to Fluzone Quadrivalent and Fluzone High-Dose vaccines, the company will distribute Flublok Quadrivalent vaccine – a recombinant protein-based flu vaccine – for the first time, the result of Sanofi Pasteur’s July 2017 acquisition of Protein Sciences. (Flublok is approved for use in people 18 years of age and older.)
The 2018-2019 flu season will see 12 to 15 times more doses of Flublok Quadrivalent vaccine for the U.S. compared to the 2017-18 season, says Guzzi. It is expected to be available at 10 times as many providers across the country compared to last year. And it has demonstrated 30 percent more protection from PCR-confirmed flu caused by any viral type/subtype, and 43 percent more protection in preventing culture-confirmed flu, compared to a standard-dose quadrivalent inactivated flu vaccine, she says.
Effectiveness questionable
Even if vaccine is readily available, some are questioning how effective it will be.
In April, a Rice University study predicted that this fall’s vaccine – a new H3N2 formulation for the first time since 2015 – will likely have the same reduced efficacy against the dominant circulating strain of influenza A as the vaccine given in 2016 and 2017. (Annual flu vaccines are formulated to protect against one type of influenza B and two strains of influenza A – one H3N2 strain and one H1N1 strain.)
“The vaccine has been changed for 2018-19, but unfortunately, it still contains two critical mutations that arise from the egg-based vaccine production process,” Michael Deem, Rice’s John W. Cox Professor in Biochemical and Genetic Engineering and professor of physics and astronomy was quoted as saying. “Our study found that these same mutations halved the efficacy of flu vaccines in the past two seasons, and we expect they will lower the efficacy of the next vaccine in a similar manner.”
Full efficacy data for the 2017-2018 flu season were still being compiled, but Rice researchers predicted it would be around 19 percent against H3N2, the type of influenza A that infected most people in the U.S. in each of the past two years. The Food and Drug Administration chose the same vaccine formulation in 2017 and 2016, in part because the dominant circulating strain stayed the same. In 2016, the vaccine had an efficacy of 20 percent, almost identical to the efficacy of 19 percent predicted by the Rice study.
(Efficacy is the measure of how effective a vaccine is at protecting the overall population. A 20 percent efficacy means that in a population, 20 percent fewer vaccinated people will get the flu compared to the unvaccinated people.)
“Getting the season’s vaccine is the best way to protect against seasonal influenza,” says LeRoy.
Introducing the 2018–19 influenza vaccine
The Food and Drug Administration’s Vaccines and Related Biologic Products Advisory Committee recommended in June that the 2018–19 trivalent vaccine to be used in the United States contain an A/Michigan/45/2015 A(H1N1)pdm09-like virus, an A/Singapore/INFIMH-16–0019/2016 A(H3N2)-like virus, and a B/Colorado/06/2017-like (B/Victoria lineage) virus. The quadrivalent vaccine recommendation included the trivalent vaccine viruses as well as a B/Phuket/3073/2013-like (B/Yamagata lineage) virus.
The B component recommendation represents a change in the influenza B/Victoria lineage component recommended for the 2017–2018 Northern Hemisphere and 2018 Southern Hemisphere influenza vaccines. The A(H3N2) recommendation represents an update to the 2017–2018 Northern Hemisphere vaccines but is the same A(H3N2) virus recommended for the 2018 Southern Hemisphere vaccine. The decision to update the A(H3N2) component was not made to address antigenic drift, but rather because the egg-propagated A/Singapore vaccine virus is antigenically more similar to circulating viruses than the egg-propagated A/Hong Kong vaccine virus recommended for the Northern Hemisphere 2017–2018 vaccine.
Source: The Centers for Disease Control and Prevention
Intranasal vaccine to make a return
FluMist® Quadrivalent intranasal flu vaccine from AstraZeneca will in all likelihood be back on the U.S. market after a couple of years off. In February, the Advisory Committee on Immunization Practices (ACIP) of the Centers for Disease Control and Prevention voted in favor of a renewed recommendation for the product for the 2018-2019 flu season following positive test results. FluMist is a live attenuated influenza vaccine (LAIV) that is sprayed into the nose. It can be used in children, adolescents and adults ages 2 through 49.
At press time, AstraZeneca – which makes FluMist – was awaiting FDA approval of the 2018-19 FluMist Quadrivalent vaccine for use during the 2018-19 season. Provided FDA approval is received, the vaccine will be available in the U.S. for the 2018-19 season, according to a company spokesperson.
“Quantities of FluMist Quadrivalent will be manufactured to meet expected U.S. demand,” says Kevin Springman, executive director, U.S. sales and marketing, infectious diseases, AstraZeneca.
In June 2016, ACIP recommended against using FluMist based on data showing poor or relatively lower effectiveness of LAIV from 2013 through 2016. The product remained off the U.S. market in the 2017-18 season.
Recent study results demonstrated that the new 2017-2018 H1N1 LAIV post-pandemic strain (A/Slovenia) performed significantly better than the 2015-2016 H1N1 LAIV post-pandemic strain (A/Bolivia), which was previously associated with reduced effectiveness, according to AstraZeneca. The antibody response induced with the new H1N1 LAIV strain was comparable to earlier data seen with the highly effective H1N1 LAIV strain included in the vaccine before the 2009 influenza pandemic.
Why get vaccinated?
The effectiveness of flu vaccine can vary, but you should still get one every year. According to the Centers for Disease Control and Prevention, flu vaccination:
- Can keep you from getting sick with flu.
- Can reduce the risk of flu-associated hospitalization, including among children and older adults.
- Has been associated with lower rates of some cardiac events among people with heart disease, especially among those who experienced a cardiac event in the past year.
- Has also been associated with reduced hospitalizations among people with diabetes (79 percent) and chronic lung disease (52 percent).
- Helps protect women during and after pregnancy.
- Can protect a baby after birth from flu. (Mom passes antibodies onto the developing baby during her pregnancy.)
- Can significantly reduce a child’s risk of dying from influenza (per a 2017 study).
- May make your illness milder if you do get sick.
- Protects people around you, including those who are more vulnerable to serious flu illness, like babies and young children, older people, and people with certain chronic health conditions.
Source: The Centers for Disease Control and Prevention