This article is more than 5 years old. Information may no longer be current.
QIV may add greater protection for 2013-2014 flu season
Click Here to Manage Email Alerts
Since 1978, the annual influenza vaccine contained three strains — two influenza A strains and one influenza B strain. This year, a number of quadrivalent influenza vaccines will be added to the list of options.
“One of the problems that we’ve had with the trivalent vaccine is that it only covers one of the two influenza B lineages that can circulate or co-circulate in any given influenza season,” said Pedro A. Piedra, MD, a professor in the department of molecular virology and microbiology and pediatrics at Baylor College of Medicine. “It is difficult to predict which of the influenza B lineages will circulate in a given year. The quadrivalent influenza vaccine (QIV) eliminates that because it ensures that both B lineages are present in the vaccine, as well as both A subtypes, the A(H3N2) and the A(H1N1).”
Infectious Disease News spoke with experts in the field about what this year’s influenza season may bring and the options for prevention and treatment of influenza infection.
Quadrivalent vaccine
The first-ever QIV (FluMist Quadrivalent, MedImmune) was approved in February; followed by Fluarix Quadrivalent (GlaxoSmithKline); Fluzone Quadrivalent (Sanofi-Pasteur); and FluLaval (GlaxoSmithKline).
Pedro A. Piedra
The vaccines will include the following strains: A/California/7/2009 (H1N1)-like virus; A(H3N2) virus antigenically like the cell-propagated prototype virus A/Victoria/361/2011; B/Massachusetts/2/2012-like virus (B Yamagata lineage); and B/Brisbane /60/2008-virus (B Victoria lineage).
FluMist Quadrivalent will be the only live-attenuated influenza vaccine (LAIV) and is indicated for use in healthy, non-pregnant patients aged 2 to 49 years. Fluarix and FluLaval Quadrivalent are inactivated vaccines indicated for use in patients aged at least 3 years. Fluzone Quadrivalent is another inactivated vaccine that is approved for use in all patients aged at least 6 months. This is the only quadrivalent vaccine approved for use in children aged 6 to 23 months.
Kathleen M. Neuzil, MD, MPH, director of vaccine access and delivery at PATH in Seattle, said there is evidence that B strains of influenza cause significant morbidity, and if a vaccine can cover strains more broadly, it makes the gamble “a little less risky.”
“If we have a predominant A strain circulating in a season, having that extra B in there isn’t going to make much of a difference,” Neuzil said. “Most years, you have at least some B, some years you have both lineages circulating. Overall, the QIV is very positive for public health, but exactly what will happen on a year-to-year basis is unpredictable depending on what strains end up circulating.”
Manjusha J. Gaglani, MD, who is Scott & White Healthcare’s Principal Investigator for CDC’s US Flu Vaccine Effectiveness Network, said she believes that the QIV will be helpful based on evidence from prior influenza seasons when B lineage has been mismatched more than half of the time.
“We have not been able to control influenza B epidemics very well,” Gaglani said. “I expect that we will have better effectiveness with the QIV for B strains.”
Live attenuated vs. inactivated vaccines
Trivalent and quadrivalent vaccines are licensed and will be available for the upcoming season, but neither formulation is preferred over the other, according to Neuzil.
Kathleen M. Neuzil
“The influenza vaccine is unique. We have many more choices than we do for any other vaccine, and what we’re trying to do is find out what the best vaccines are for certain age groups,” she said. “That’s not always easy because we generally look at vaccine efficacy for a single year or 2 years, but we know that influenza changes and the answer one year might not be the same as the answer the next. I’m going to keep emphasizing that getting any influenza vaccine is better than no influenza vaccine.”
However, Piedra said when compared head-to-head with the trivalent inactivated influenza vaccine, the trivalent LAIV tended to be more effective in young children.
“The LAIV is only approved for children 2 years of age or older, and it’s primarily for healthy children, so that means that for children under 2 years, the preferred vaccine, and the only vaccine, would be the inactivated influenza vaccine,” he said. “Likewise, if you had a high-risk medical condition, you would want to receive the inactivated influenza vaccine; that’s the one that’s recommended.”
Although the LAIV may be better for young children, it is not indicated for use in high-risk children.
Changes in vaccination recommendations
This year, the ACIP made few changes to recommendations regarding QIV. Those aged at least 6 months are still recommended to receive influenza vaccination. According to summary recommendations released by the CDC and ACIP, “within approved indications and recommendations, no preferential recommendation is made for any type or brand of licensed influenza vaccine over another.”
Children aged 6 months to 8 years are also recommended to receive two doses of the influenza vaccine, with 4 or more weeks in between doses, the first year they are immunized against influenza.
“The argument is that when they first get the vaccine, those young children haven’t had a lot of exposure or infection with influenza, so to start building an immunity, the second dose boosts or gives an increase of response compared to a single dose,” Leonard R. Krilov, MD, Winthrop University Hospital, Mineola, N.Y., said. “That’s only the first year they get the vaccine, or if they hadn’t had two doses total previously.”
Other new ACIP recommendations included modification of the egg allergy algorithm to include recombinant hemagglutinin vaccine and a trivalent formulation, and language to address those with no history of egg exposure but questionable egg allergy testing.
Leonard R. Krilov
The modification of the egg allergy algorithm includes offering the recombinant influenza vaccine to adults aged 18 to 49 years with egg allergies who have hives and also for those with symptoms of severe or life-threatening allergy other than hives.
Language addressing those with no history of egg exposure recommends that those with questionable egg allergy testing consult a physician with expertise in the management of allergies before vaccination.
Levels of hospitalizations
Influenza-associated hospitalizations began to rise in mid-December 2012, with sharp increases seen among those aged 65 years and older. The cumulative hospitalization rates among seniors went from 17 per 100,000 people for the week ending Dec. 15, 2012 to 182 per 100,000 during March 17-23, 2013. Hospitalization rates leveled off in March, but this was the highest reported proportion of patients aged 65 and older hospitalized for influenza since this kind of record-keeping began during the 2005-2006 season. Patients aged 65 and older accounted for 50% of all reported hospitalizations, according to the CDC.
As of July 13, 154 laboratory-confirmed influenza-associated pediatric deaths were reported to the CDC for the 2012-2013 influenza season. Influenza A lineages dominated overall, particularly A(H3N2). Last year accounted for the most pediatric deaths associated with influenza since the 2009 to 2010 pandemic. Eighty-one of all pediatric deaths were associated with a B lineage; 34 with an unknown influenza A subtype; 32 with influenza A H3N2; four with A H1N1; two with both A and B lineages; and one with an undetermined type. However, most of the deaths occurred in children unimmunized against influenza.
As for the start of the 2013-2014 influenza season, available data (week ending Oct. 12) so far indicate that influenza activity is low in the United States. Of 3,534 specimens tested and reported by US World Health Organization and National Respiratory and Enteric Virus Surveillance System collaborating laboratories during week 41, 166 (4.7%) samples tested positive for influenza.
Transmission of H7N9
On April 1, WHO was notified of human infection with a new avian influenza A(H7N9) virus, and since then, more than 130 cases have been reported and at least 45 deaths. However, there has been limited evidence of human-to-human transmission.
“The fact that we’ve already had an outbreak makes H7N9 a big concern because of certain things we know about the virus,” Alicia Fry, MD, medical officer in the influenza division at the CDC’s National Center for Immunization and Respiratory Diseases, said. “Right now, it seems very much like the H5N1, in that it causes severe illness but that it’s not very transmissible from human-to-human.”
The CDC and WHO are continuously monitoring H7N9 for any new infections or human-to-human transmissions.
“Although there is limited action with H7N9 now, we have seen a pattern when, during influenza seasons or different times of year, even avian viruses have a bit of seasonality,” Neuzil said. “It’s hard to know where this one is going to go. It absolutely deserves the attention and caution that it’s receiving, but there’s no time for panic. It’s not the time to panic yet.” – by Amber Cox
References:
Block SL. Pediatr Infect Dis J. 2013;31:745-751.
CDC. MMWR. 2013;62:119-123.
CDC. MMWR. 2013:62:124-130.
CDC. Summary Recommendations: Prevention and Control of Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices - (ACIP) - United States, 2013-2014. Available at: www.cdc.gov/flu/professionals/acip/2013-summary-recommendations.htm. Accessed Aug. 14, 2013.
For more information:
Alicia Fry, MD can be reached at afry@cdc.gov.
Manjusha J. Gaglani, MD, can be reached at mgaglani@sw.org.
Leonard R. Krilov, MD, FAAP, can be reached at Winthrop University Hospital, 120 Mineola Blvd., Suite 210, Mineola, NY 11501; email: lkrilov@winthrop.org.
Kathleen M. Neuzil, MD, MPH, can be reached at 2201 Westlake Ave., Suite 200, Seattle, WA 98121; email: kneuzil@path.org.
Pedro A. Piedra, MD, can be reached at Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030; email: ppiedra@bcm.edu.
Disclosures: Fry, Gaglani, Krilov and Neuzil report no relevant financial disclosures. Piedra reports being a member of the speakers bureau for MedImmune.