November 01, 2008
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Influenza vaccinations: Don’t stop now

Vaccination efforts should continue into December and beyond.

Data that track influenza vaccination patterns confirm what most of us know intuitively: If you’re not vaccinated by Thanksgiving, it’s unlikely you’ll be vaccinated at all this year.

However, there is no medical rationale for this arbitrary cut-off date. It is medically relevant to keep vaccinating against influenza through December and beyond. By vaccinating for a longer period, we’ll reach more patients and help them solidify good habits. Past vaccination history is a key factor in vaccination decisions; once people have received an influenza vaccine they are more likely to get it again.

Influenza most often peaks around February in the United States. In seasons with high attack rates, more than 30 million influenza cases will occur from February to May. Since it takes only about two weeks to develop immunity following vaccination, the importance of vaccinating past November is evident. By doing so, we can move toward the important public health goal of protecting millions more people.

CDC recommendations

The CDC now recommends annual influenza immunization for more than 250 million Americans. Highlighting the importance of vaccinating beyond November, the CDC has scheduled this year’s National Influenza Vaccination Week for December 8-14.

Our influenza vaccine supply has been growing steadily for several years. Manufacturers that supplied vaccine previously are increasing their capacity, and new manufacturers have entered the market recently. This year, six manufacturers will supply more than 140 million doses in the United States.

Manufacturers have signaled that they can continue to increase supply in coming years, but the sad fact is that we have not used all of the vaccine available to us in the past several seasons. One reason may be our focus on vaccinating only during the traditional October through November timeframe. It has become clear that full implementation of the CDC recommendations cannot be accomplished in this short window. It stands to reason that if we intend to vaccinate more people each year, it will take longer to be successful.

Expanded recommendations

As infectious disease experts have learned more about who is affected by the substantial morbidity and mortality associated with influenza, immunization recommendations have expanded. Not long ago, the need for influenza vaccine was only associated with people aged 65 and older. Now, the vaccine is recommended for about 85% of the American public, including all of our nation’s children (beginning at age 6 months), everyone aged 50 and older, and those in-between with certain underlying medical conditions – not to mention every healthcare worker and anyone in close contact with high-risk individuals.

People in different categories have different levels of risk, but all can benefit from annual vaccination. Elderly individuals are at the highest risk of death from influenza. The vaccine may not prevent infection in as many of these people as we’d like, but it can mitigate its clinical course, helping elderly people avoid the complications of pneumonia, hospitalization and even death.

Infants and toddlers are at the highest risk of hospitalization from influenza. In fact, the burden of influenza in this group may be even greater than we recognize. Data from the New Vaccine Surveillance Network – established by the CDC in 1999 to evaluate the impact of new vaccines and vaccine policies through active sentinel surveillance at three American medical centers (Rochester, N.Y.; Nashville; Cincinnati) — show that “few children who had laboratory-confirmed influenza [in the 2002-03 or 2003-04 influenza seasons] were given a diagnosis of influenza by the treating physician in the inpatient [28%] or outpatient [17%] setting.” (Poehling K, et al. NEJM. 2006;355:31-40.)

Children aged younger than 5 years who contract influenza make many medical visits and often receive antibiotics. And school-aged children, the group most recently added to the annual recommendations, are at the highest risk of infection. Millions of school days are lost every year to influenza; millions more work days are lost by parents who must stay home to care for their children.

We are also seeing an increasing number of cases of methicillin-resistant Staphylococcus aureus co-infection in children with influenza. While the overall risk of MRSA co-infection remains low, these reports provide a stark reminder that influenza infection can set the stage for any number of bacterial superinfections, some of which can be quite difficult to treat. Prevention is key.

Health care professionals

In 2004, I wrote an editorial in this same space calling on my fellow health care professionals to follow the CDC recommendations and get vaccinated every year. Although more health care professionals than ever are heeding the call to get vaccinated, we’re still falling short of public health goals.

With an annual coverage rate of about 40 percent among healthcare workers, six in 10 of us are still willing to risk getting infected and passing influenza on to our patients. It is our professional responsibility to do them no harm. When we fail to do all we can to protect our patients, we are failing in our professional responsibility. And when we don’t protect ourselves we also risk being unavailable to provide care during the winter respiratory season — a time when our services are needed most critically.

By getting vaccinated annually we also send a very positive message to our patients and colleagues. We are role models; our actions matter as much as our words, which clearly matter greatly. A recent survey conducted by the National Foundation for Infectious Diseases (NFID) showed once again that patients rely on us for medical advice. Across all ages and levels of health risk, 70% of patients say they would accept an influenza vaccine if their health care professional recommended it.

Stepping up efforts

NFID is encouraging vaccination throughout the influenza season to protect as many Americans as possible. This summer, NFID sponsored a supplement to the American Journal of Medicine on this topic.

One of the articles, by Gregory Poland, MD, of the Mayo Clinic, and colleagues, discusses the substantial burden of influenza infection and the rationale for the CDC recommendation that at-risk patients be vaccinated throughout the influenza season. The article also presents data from a newly released study in which millions of patients at risk for influenza saw a health care provider on average 2.2 times between November and February yet did not receive influenza vaccine.

NFID is pleased to make the entire American Journal of Medicine supplement available on-line free of charge. The supplement can be accessed on the journal’s website (www.amjmed.com).

An outdated paradigm

For most health care professionals, the end of November signals the end of substantial efforts to reach out to patients and get them vaccinated. And for most patients, Thanksgiving signals the end of the period when they actively seek influenza vaccine. But this represents an outmoded way of thinking about vaccination.

It hails from a time when we had much less vaccine available and most, if not all of the supply was used by November. But we have many more doses available now. The six manufacturers providing influenza vaccines in the United States have already delivered a substantial portion of the more than 140 million doses they expect to provide this season.

The October-November vaccination period also hails from a time when far fewer people sought vaccination every year. As more Americans get the message that influenza is serious and avoidable, we need to increase their opportunities to get vaccinated. Vaccinating for a longer period is an effective strategy for expanding vaccine access.

As I like to say, vaccine left in the refrigerator cannot prevent influenza. It’s time to make full use of the millions of vaccine doses available to us, and the entire season in which we need them, to protect millions more Americans than ever before.

PERSPECTIVE

Bill Schaffner is a long-standing friend, and one with whom I share many interests. He has written several guest columns on influenza vaccines in years past, and this one is particularly timely. In addition to his academic positions, he is the President-Elect of the National Foundation for Infectious Diseases.

Theodore C. Eickhoff, MD

Chief Medical Editor

For more information:
  • William Schaffner, MD, is professor and chairman of the department of preventive medicine in the division of infectious diseases at Vanderbilt University School of Medicine in Nashville.