The 2010-2011 influenza vaccine and related matters

The FDA’s Vaccines and Related Biological Products met on Feb. 22 for the annual determination of the composition of influenza vaccine for the following season.

I was again privileged to attend and participate. It was a surprisingly non-contentious meeting. After the usual presentation of current surveillance data from around the world and discussions of the availability of candidate strains and reagents, the panel voted unanimously to substitute the current pandemic A H1N1 A/California/7/2009–like virus for the previous seasonal A H1N1 strain; update the current A H3N2 strain by using an A/Perth/16/2009 or A/Wisconsin/15/2009–like virus; and retain the B/Brisbane/60/2008-like virus from the Victoria lineage present in the 2009-10 seasonal vaccine.

When all was said and done, the panel endorsed the WHO Northern Hemisphere vaccine recommendations for all three vaccine strains.

The A H3N2 strain has been notably absent around the world. The last flurry of A H3N2 activity around the world occurred last fall in China. As time goes by, it seems increasingly likely that Don Kaye, MD, was correct in his Point/Counter comments in the January issue of

Infectious Diseases in Children. He opined that we have probably seen the last of the A H3N2 virus for several generations, and indeed, the lessons of history fully support his view. I’m not quite ready to concede his point yet, but I suspect I will be if A H3N2 activity continues to be absent for several more months.

WHO officials were not ready to eliminate the A H3N2 strain from next year’s vaccine, nor was the FDA’s advisory committee. If another year goes by without H3N2 reappearing anywhere, however, then I believe there will be adequate justification to eliminate that component from influenza vaccines. A H3N2 strains have been circulating as the predominant epidemic strain for more than 40 years; that strain was introduced in 1968. For most of us, it will be difficult to imagine influenza vaccine without an H3N2 component, but that is likely to happen. It’s also likely that H3N2 strains will ultimately re-emerge, perhaps 40 to 60 years downstream.

Two days after the FDA advisory meeting, CDC’s Advisory Committee on Immunization Practices voted to recommend annual influenza immunization for everyone, save for infants younger than 6 months of age; people with true egg allergy; and people with certain neurologic conditions, eg, a history of Guillian-Barre syndrome. Actually, this recommendation is a relatively modest incremental step in the immunization of adults, for the previous recommendations already included adults who lived with or provided care to children or adults at increased risk. Nonetheless, influenza vaccine is now another “universal use” vaccine.

Regular readers of this column will recognize that I am generally a hawk when it comes to vaccines and immunization. I’m a bit surprised, therefore, that I find myself somewhat less than enthusiastic about this recommendation. If influenza vaccine were somehow the perfect vaccine, I would be fully in support of this recommendation. But we know it is far from that. Clinical trial efficacy, even under the most ideal conditions, is rarely more than 80% to 85%; it goes down from there when one adds in older age, underlying conditions, strain mismatches and the like. Some day we may have the perfect influenza vaccine, but not yet. Until such a day, the present vaccine is good at best, mediocre much of the time, and ineffective some of the time.

The great danger here is that we are overselling this vaccine. Public expectations might be raised to a wholly unsupportable level, until eventually, some set of circumstances will cause it to come tumbling down, with consequent damage to the whole immunization enterprise, and more grist for the anti- vaccination mill.

On the same day the ACIP made its “universal use” recommendation, WHO’s emergency committee of experts recommended maintaining the current level 6 (pandemic) alert level and declined to move to a post-peak level. Certainly, the pandemic in North America has tapered off to normal or near normal levels, and the same is true for most but not all Northern Hemisphere countries. The virus is still active in Eastern Europe and Central Asia, and there are reports of increasing activity in several West African countries. Furthermore, Southern Hemisphere countries have seen but one epidemic wave, and their winter season looms ahead. Thus, the WHO is erring on the side of caution.

Nor is North America out of the woods yet. Although there is yet no sign of increased influenza activity in the United States, a late winter or spring “wave” might yet occur.

Mandatory flu vaccines

Finally, the earlier endorsements of mandating influenza vaccine for health care staff appears to be gaining momentum. The reported success of this approach at Virginia Mason Hospital in Seattle has prompted a number of other medical centers or jurisdictions to pursue similar approaches.

The list now includes the Hospital Corporation of America, Johns Hopkins Health System, the University of Iowa Hospitals, the Hospital of the University of Pennsylvania, the Children’s Hospital of Philadelphia and the Department of Defense.

Organizations that have endorsed mandatory health care worker immunization include the Infectious Diseases Society of America, and the American College of Physicians.

A surprising 77% of hospital epidemiologists surveyed on their experiences with the H1N1 pandemic favored mandatory immunization of health care workers (Lautenbach. CID; 50:523-7), As did Barnes Jewish Healthcare, a 13- hospital consortium based in St. Louis.

In two papers published recently in Clinical Infectious Diseases and Infection Control and Hospital Epidemiology, investigators report a 98% compliance with mandated influenza vaccine for all hospital employees, including house staff, fellows, and the like — anyone who receives a check from the Consortium. It should be pointed out, however, that attending physicians were excluded from the “mandate” provisions because they were not Consortium employees. In most medical centers, including my own, attending physicians have been among the toughest nuts to crack.

My own hospital achieved a 75% health care worker immunization rate for seasonal influenza vaccine last fall using a non-mandated approach that included a lot of staff education and encouragement. That’s not ideal, to be sure, but still a substantial improvement over previous years. At least for the next several years, mandating influenza vaccine for health care workers will be a tough sell here.

Theodore C. Eickhoff, MD, is a Professor of Medicine at the University of Colorado Health Sciences Center in Denver and an Infectious Diseases in Children Editorial Board member.