CDC Says Influenza Vaccine Only 18% Effective This Year

Alicia Ault

February 26, 2015

The influenza vaccine this season has had little to no efficacy, in particular against the predominant A strains that have been circulating, said researchers from the Centers for Disease Control and Prevention (CDC) today.

They presented new data to the CDC's Advisory Committee on Immunization Practices (ACIP) that suggested the vaccine was only 18% effective for all ages.

It had previously been reported that the influenza vaccine was only 23% effective this year.

There was also a hint that both the inactive and the live-attenuated vaccine offered perhaps no protection against H3N2 A strains this influenza season.

Both vaccines did immensely better in protecting against B strains — at close to 95% effectiveness — but those are more rare.

CDC researchers said that the lower effectiveness against the A strains was likely due to what appears to be a genetic drift since the vaccine was formulated. The CDC reported in January that 70% of the A strains observed in circulation were different from the vaccine strains.

The agency also reported — again — that the live-attenuated vaccine (MedImmune's FluMist) does not appear to be very effective in children.

This countered what the CDC had previously advised, when it told physicians to choose the nasal spray over the vaccination.

The ACIP panel voted to approve language showing no preference for next influenza season that either FluMist or an inactive vaccine would be considered appropriate for healthy children aged 2 to 8 years who have no contraindications.

The panel also voted that it would express no vaccine preference for those aged 2 to 49 years.

No Universal Meningitis B Recommendation

The ACIP also considered vaccination for meningococcal disease caused by serogroup B. According to the latest CDC data, there were some 500 total cases of meningococcal disease reported in the US in 2012, of which 160 were caused by serogroup B.

Until recently, vaccines were only available for four of the five main strains of Neisseria meningitides. Two serogroup B vaccines have now been approved: Pfizer's Trumenba in October and Novartis' Bexsero in January, both for use in 10- to 25-year-olds.

But the ACIP panel declined to recommend universal vaccination. Instead, it voted to recommend use of the vaccine in about 300,000 to 350,000 individuals aged over 10 years considered at high risk for serogroup B, including: patients with persistent complement component deficiencies; those with functional or anatomic asplenia, including sickle cell disease; microbiologists who work with N. meningitides; and people at risk because of outbreaks.

The CDC told the ACIP that such outbreaks — often on college campuses — are rare, though there have been two at universities in 2015 already.

The ACIP said that it would discuss universal vaccination at its next meeting June 24-25.

At least one organization that had been pushing for universal vaccination said it was happy that the ACIP supported the serogroup B vaccine for those at high risk, but that it was only a first step. "Leading up to the June meeting, when broader recommendations will be discussed, we will continue to give voice to the concerns and viewpoints of people affected by this disease," Lynn Bozof, president of the National Meningitis Association, told Medscape Medical News. "By doing this, we hope to encourage policymakers to do the right thing and recommend these vaccines to protect adolescents."

Laura York, PhD, global medical lead for meningococcal vaccines at Pfizer Vaccines, said in a statement that the company was "encouraged by this initial ACIP recommendation." But, she added, "We believe public health would be best served by broader routine recommendations for adolescents and young adults who are currently only protected against serogroups A, C, W and Y."

New HPV9 Vaccine Backed

The ACIP also took up Gardasil 9 (Merck), the human papillomavirus (HPV) vaccine that was approved by the FDA in December for use in 9- to 26-year-old girls and 9- to 15-year-old boys.

The committee voted to approve a recommendation that Gardasil 9 could now be added to the list of appropriate HPV vaccines. It did not change its current recommendation on when to start vaccination or through what ages for females and males.

It also approved a recommendation that physicians could use any of the available vaccines to complete a dose series if they did not know which had been used initially.

In June, the ACIP will discuss whether Gardasil 9 should be given to individuals who have completed vaccination with any of the earlier vaccines.

Yellow Fever

Finally, the ACIP aligned its recommendation on yellow fever vaccine with the World Health Organization, which has stopped urging boosters every 10 years for most travelers. Some individuals should still get a booster, said the ACIP, including those traveling to endemic areas.


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