Influenza Vaccines Efficacy in Elderly Found Wanting

Influenza Vaccine’s Efficacy in Elderly Found Wanting

By Rebekah McCallister

Most deaths caused by influenza occur in older persons aged ³60 years, which is why annual immunization is recommended in this age-group. But until now, the question of how effective is influenza vaccination in these individuals remained unanswered.

Recent analysis of vaccination data suggest that the vaccine is only moderately effective for persons aged ³65 living in the community and is only slightly more effective for residents of long-term care facilities, although it does help protect against complications, according to Tom Jefferson, MD, of Cochrane Vaccines Field, ASL, Alessandria, Italy, and colleagues, who published their findings in the Lancet (2005;366:1165-1174).

In 2000, 40 of 51 developed or developing countries recommended vaccination for all individuals aged 60 to 65 years or older. Analysis of data from 15 studies revealed that in elderly persons living in the community, inactivated influenza vaccines were not effective against influenza-like illnesses, influenza, or pneumonia but did prevent up to 30% of hospitalizations for pneumonia.

A second analysis of data from 29 studies showed that in elderly residents of long-term care facilities, inactivated influenza vaccines prevented up to 42% of deaths from influenza and pneumonia.

“We need a more comprehensive and perhaps more effective strategy in controlling acute respiratory infections, relying on several preventive interventions that take into account the multiagent nature of infectious respiratory disease and its context,” said Dr Jefferson.

According to the Centers for Disease Control and Prevention, individuals aged >65 years and those with certain chronic comorbidities may have lower postvaccination antibody titers and, as a result, can remain susceptible to infection and flu-related upper respiratory tract illness.

The United States expects to receive influenza vaccine from 4 manufacturers for the 2005-2006 influenza season, including 60 million doses of trivalent inactivated vaccine (TIV) (Fluzone) from Sanofi Pasteur, 8 million doses of TIV (Fluarix) from GlaxoSmithKline, and approximately 3 million doses of live attenuated influenza vaccine (FluMist) from MedImmune Vaccine (MMWR. 2005;54:850). Chiron Corporation has received all necessary approvals from the FDA and the United Kingdom Medicines and Healthcare Products Regulatory Agency to begin supplying its TIV (Fluvirin) to the US market; however, in October, the company announced that vaccine production will fall short of its previously anticipated range of 18 to 26 million doses due to “adaptation to new processes and procedures implemented in remediation.”

The 2005-2006 influenza vaccine contains A/California/7/2004 (H3N2)-like, A/New Caledonia/20/99 (H1N1)-like, and B/Shanghai/361/2002-like influenza virus antigens. Patients who are severely allergic to eggs, who have had a severe reaction to an influenza vaccination in the past, or who have a history of developing Guillain-Barré syndrome in the 6 weeks after receiving an influenza vaccination should consult their physician before being immunized.