Employee health professionals with voluntary seasonal influenza vaccination can expect a tougher sell this year to skeptical healthcare workers, many of whom will recall last year’s mismatched batch that whiffed on a widely circulating H3N2 strain that had antigenically drifted.

“It may be the most frequent question we get this year because many people will remember that last year it was not a very effective vaccine,” said longtime vaccine advocate William Schaffner, MD, chairman of the department of preventive medicine at Vanderbilt University Medical Center in Nashville. “The message is to keep getting it out there. It’s not a perfect vaccine. Its effectiveness varies, but still each and every year it is the best thing we can do to prevent influenza in ourselves and those around us, including our patients. We need to get vaccinated because it is the single best thing we can do on our patient’s behalf.”

The CDC estimates that the 2014-2015 vaccine had an efficacy of 18% against H3N2 influenza A and 45% against influenza B viruses. Overall, the efficacy estimate was 23%. In the decade preceding, flu vaccine efficacy varied from 10% (2004-2005) to 60% in (2010-2011.)¹

The generally accepted efficacy estimate for seasonal flu vaccine over time is 59% among people age 18-64. Protectiveness falls off in the younger, older and those with underlying illness that weakens the immune response. Vaccine advocates emphasize, however, that even a low level of flu protection can make a difference in the morbidity and mortality of those infected.

“You are trying to keep people out of the hospital and out of the morgue. That’s the goal,” says Paul Offit, MD, chief of Infectious Diseases at the Children’s Hospital of Philadelphia.

Selecting the seasonal flu vaccine strains is a bit dicey to begin with, as selections are gleaned from ongoing flu surveillance centers in more than 100 countries worldwide. The viruses targeted by the seasonal flu vaccines are updated each year based on which strains are circulating, how rapidly they are spreading, severity of disease, and other factors. Flu viruses that appear well matched to a vaccine may subsequently antigenically drift, making the vaccine designed to stop them less effective. A pandemic can arise when a complete antigenic “shift” occurs, meaning there can be little assumed immunity or vaccine protection until another vaccine is developed.

The 2015-2016 influenza vaccine was made to protect against the following three viruses:

• A/California/7/2009 (H1N1)

• A/Switzerland/9715293/2013 (H3N2)-like virus

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

In addition to these trivalent vaccine, there is a quadrivalent 2015-2016 flu vaccine that protects against the aforementioned trio and an additional B virus (B/Brisbane/60/2008-like virus). For healthcare workers with an aversion to needles, a new needleless jet injector has been approved for use this year. The FDA approved use of the PharmaJet Stratis 0.5ml Needle-free Jet Injector for delivery of one particular flu vaccine (AFLURIA® by bioCSL Inc.) in people 18 through 64 years of age. The injector penetrates the skin with a narrow, high-pressure stream of fluid rather than a hypodermic needle.

Healthcare workers need to get vaccinated to protect high-risk patients even if staff are full of vigor and say invariably every year, “I never get the flu,” Schaffner says. “Influenza infection causes minimal or no symptoms in up to 25% [of people infected],” he adds. “But these healthcare workers can still shed and spread the flu virus.”

Likewise, employee health professionals have no doubt heard that the reason for flu declination is, “I’ll stay home if I get sick.” Yet it has been observed time and again that healthcare workers will report to work sick, hence the term “presenteeism.”

Flu shot mandates could cut off all this annual point-counterpoint, as hospitals that have gone this route typically achieve a greater than 90% immunization level in very short order. However, even proactive employee programs may find it difficult to get out of the 70% area through voluntary efforts. In any case, the overall trend — no doubt boosted by the increasing mandatory programs — is going upward. Citing unpublished CDC data recently in Nashville at the annual conference of the Association for Professionals in Infection Control and Epidemiology (APIC), Schaffner noted rates of healthcare worker flu immunization climbing from 67% (2011-2012) to 72% (2012-2013), and to 75% (2013-2014).

The trends should keep moving north as more hospitals go to mandatory policies, and the Centers for Medicare & Medicaid Services (CMS) keeps the pressure on by requiring public reporting of healthcare flu immunization rates. These publically available rates on the CMS Hospital Compare website have a way of landing in the local paper one morning, showing how a community’s hospitals are faring and comparing their immunization rates.

“It clearly brought it more to our administration’s attention,” Schaffner says. “Mind you they had been discussing how vigorously to do this for a number of years and they wanted to go up. The occupational health service did absolutely everything it could, but we got up into the 70s and that’s apparently where we got stuck. Our administration said that is not sufficient and instituted a mandatory program. [Our program] does not include firing people, but we follow up absolutely every individual who did not have a flu vaccination recorded. Once we did that — and that took a lot of work — last year we got over 90%.”

REFERENCE

1. Centers for Disease Control and Prevention. Seasonal Influenza Vaccine Effectiveness, 2005-2015 June 24, 2015: http://1.usa.gov/1NNgxln.