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8th Canadian Immunization Conference

Toronto, Ontario / November 30-December 3, 2008

Every office visit represents an opportunity for physicians to bring adults up to date with required vaccines, states adult immunization advocate Dr. Allison McGeer, Professor of Laboratory Medicine and Pathobiology, University of Toronto, and the list of vaccines they need to catch up on is growing as new ones become available.

Routine vaccines for adults currently include a tetanus and diphtheria booster; acellular pertussis; the measles-mumps-rubella vaccine for adults born after 1970; the varicella vaccine if adults are still susceptible to it; the annual influenza shot; and the pneumococcal polysaccaride vaccine for adults >65 years of age. The human papillomavirus is licensed for use in women up to the age of 26, the meningococcal vaccine may be considered for young college students, especially those living in dorms, and the herpes zoster vaccine should be considered for adults <u>></u>60 years of age.

An overview of how well the country is keeping up with traditional adult immunization indicates there is considerable room for improvement. According to the 2006 Adult National Advisory Committee on Immunization (NACI) survey, influenza coverage has remained relatively constant since the first survey was carried out in 2001, at approximately 38% for adults with chronic medical conditions, approximately 64% for healthcare workers and approximately 70% for those >65 years of age. Pneumococcal coverage also remained constant, at about 42% of seniors and approximately 17% of adults with chronic medical conditions. Preliminary results from the updated NACI survey on adult immunization indicate that vaccination rates have remained very similar. Given these rates, “we still fall short of national goals for adults with chronic medical conditions,” the survey authors concluded.

As Dr. McGeer relates, physicians need to ensure some sort of system is in place to capture adults in a timely way for new and catch-up vaccinations. In fact, as she pointed out, having a system in place is exactly what has made pediatric vaccination so remarkably successful. “Pediatric vaccination works because physicians do it routinely,” Dr. McGeer notes. “They know they are going to be giving vaccines to infants at specific times; they book these times, they recommend pediatric vaccines to parents and parents know they need to be given, so the whole system is in place.

Recommending Adult Immunization

In contrast, no such system exists for routinely vaccinating adults—“adults do not ask for vaccines, they do not expect them, and adult vaccination can be more complicated because adults need to know their vaccine history; you need to discuss lifestyle and occupation issues with them and all of this when a lot of other issues are on the table,” she explains. Complicating adult vaccination further, pediatric vaccination is primarily a public health function in many provinces so many physicians do not even deliver pediatric vaccines. Transforming public health venues to systems suitable for adult vaccination is not impossible, as Dr. McGeer suggests, but it would require “considerable thought and organization.”

Then there are special populations of patients who are significantly underprotected against many communicable diseases and who require special attention. In one study, over one-third of newly-arrived immigrants and refugees were found to have inadequate immunity to measles, mumps or rubella, among them women of child-bearing years who are particularly at risk should they contract these infections (Greenaway et al. Ann Intern Med 2007;146(1):20-4). As the authors of this particular study pointed out, susceptible immigrants may unwittingly import measles, mumps or rubella on returning from visits with friends or relatives living in areas where the infections are still endemic, thus heightening communicable disease risk. Findings such as these highlight the need to provide “catch-up” vaccinations in foreign-born individuals in particular, investigators concluded.

According to another study, young immigrants are also still susceptible to varicella and a targeted varicella vaccination program for newly arrived young immigrants would be both beneficial for immigrants in particular and cost-effective as well (Merrett et al. Clin Infect Dis 2007;44(8):1040-8).

All adults themselves are often unaware of their need for vaccination and probably do not appreciate how protective vaccination can be. Public health has done much over the years to report how important the burden of influenza illness is among the elderly but the elderly often either do not realize they require influenza vaccination every year or they do not take influenza seriously. In Quebec, only 65% of the elderly received the influenza vaccine in 2005-2006. Researchers recently reported that the risk of having a myocardial infarction was over 50% less some two years after adults received the pneumococcal vaccine compared with individuals who did not receive the vaccine (Lamontagne et al. CMAJ 2008;179(8):773-7). Less than half of eligible elderly patients in Quebec received the pneumococcal vaccine in 2005-2006. Vaccination against pneumococcus also reduces the risk of mortality and of the need for ICU admission due to community-acquired pneumonia by almost 40%, despite the fact that the vaccine does not prevent CAP, according to another study (Johnstone et al. Arch Intern Med 2007;167(18):1938-43).

For adults with diabetes, researchers found that type 1 and type 2 diabetes were associated with a 25% to 75% increase in the relative risk of patients requiring hospitalization for pneumonia, emphasizing the value of ensuring older adults with diabetes receive the pneumococcal vaccine as well as their annual flu shot (Kornum et al. Diabetes Care 2008;31(8):1541-5).

“If patients never come to see you, then that one visit when there is a crisis may be your only opportunity to deliver the vaccines they need so it is important to build this into the practice,” Dr. McGeer stresses. “Making a recommendation for a vaccine has a very large impact on patients getting vaccinated so a physicians’ recommendation is critically important as well.”

Infection a Major Cause of Morbidity

As reported in a recent statement by the Société québécoise de gériatrie, infectious illness remains a major cause of morbidity and mortality among the elderly. Both the incidence of infectious illness and the associated severity increase with age as does the risk of nosocomial infections. Meta-analyses of many studies indicate that the influenza vaccine prevents 56% of respiratory illnesses among the elderly, half of the hospitalizations for pneumonia and 68% of deaths from these infections.

Even if the vaccine cannot completely prevent influenza in all residents in long-term care, it will prevent hospitalization and pneumonia in 50% to 60% of episodes and death in 85% to 90% of episodes, according to the Société. As for pneumococcal disease, the same group pointed out that pneumococcal infections are the primary cause of death from infectious diseases after the age of 70 years. Whatever antibiotics are used, mortality rates from invasive pneumococcal disease remain high. While not perfect, the efficacy of the pneumococcal vaccine for the prevention of invasive pneumococcal disease is between 55% and 80% among the elderly.

“Health professionals have a crucial role to play in the prevention of infectious disease via vaccination,” the Société stated. “Studies have demonstrated that health professionals are the most important source of information concerning vaccination, especially among patients <u>></u>65 years of age, and a recommendation for vaccination by a healthcare professional is the most important factor in a patient’s decision to have themselves vaccinated or not. Even if the [elderly’s] immunological response to vaccination is weaker than it is in pediatric vaccination, prevention and reduction of clinical consequences [from infection] are very important effects in and of themselves and should be the goal of vaccination in the elderly.”

Related sessions of interest at this meeting:

Plenary V. “Vaccine Effectiveness–Evidence of Impact.” P De Wals.

P104. “The State of Adult Vaccination in Ontario: A Focused Multisectional Consultation.” B Pakes, S Wilson, A McGeer.

P74. “2006 Adult National Immunization Coverage Survey.” AM Frescura, L Belzak.

P94. “Exploring Barriers to Immunization Using a Population Health Approach.” S MacDonald, CV Newburn-Cook, M Allen.