Until we get a vaccine for it.
I am also doubtful that immunising the elderly actually makes that much difference to the death rates because the immune response is usually rather weak and does not last that long.
The decision to vaccinate the old folk is a political decision not a scientific one.
https://academic.oup.com/cid/article/46/7/1078/291620
One major health issue arising with age is the increasing prevalence and severity of some infectious diseases, which partly reflects the age-related decline in immune function. Pneumonia, infections of the urinary tract and the skin, and reactivation of infection with latent pathogens, such as varicella zoster virus and
Mycobacterium tuberculosis, are common in the elderly population. Influenza, for example, is often associated with severe complications and secondary infections in elderly persons.
During an epidemic influenza season, 3–5 million cases of severe disease and 250,000–500,000 deaths occur worldwide [2]. In industrialized countries,
most deaths associated with influenza occur among elderly persons. In developed countries, such as the United States,
deaths due to pneumonia and influenza account for >3% of all deaths in people aged ⩾65 years [3]. Vaccination is of crucial importance in preventing infection and protecting the vulnerable elderly population from disease. Because the efficacy of a vaccine depends on the quality of the immune response, immunocompromised persons, such as very young infants and elderly persons,
are likely to be insufficiently protected [4]. Thus, over the past decade, a large number of studies have shown that a variety of vaccines are less efficient in elderly persons. Annual vaccination against influenza, for example, is recommended in most developed countries for persons with underlying chronic diseases and for everybody aged >60 or >65 years, depending on individual national recommendations. However, antibody responses after vaccination are lower in elderly persons than in young adults [5]. Decreased IgA and IgG antibody concentrations, delayed peak antibody titers, and a faster decline in titers occur, especially in very old and frail persons. For example, seroprotection against influenza virus strains is only 29%–46% in persons aged ⩾75 years, compared with 41%–58% in persons 60–74 years of age (table 1). Because nonadjuvanted influenza virus subunit vaccines show lower seroprotection and seroconversion rates than do adjuvanted subunit, virosomal, or split vaccines [14, 15], they should not be administered to elderly persons. There are >90 serotypes of
Streptococcus pneumoniae, and many of these frequently affect young children and elderly persons. Fifteen percent to 30% of cases of pneumonia are associated with invasive pneumococcal disease (e.g., bacteremia or meningitis), with a case-fatality rate of up to 40% for persons aged ⩾85 years [10]. Currently, the 23-valent pneumococcal polysaccharide vaccine offers protection against invasive pneumococcal disease (50%–70%) in the general elderly population but has only moderate effects (20%) in the high-risk elderly population [16]. Moreover, the vaccine has only little effect against pneumonia. Although 7-valent conjugate polysaccharide vaccines have been developed that improve vaccine responses in young children,
these vaccines failed to improve immunogenicity in elderly persons [17].
