Vac­cines for an aging pop­u­la­tion

Financial Mirror (Cyprus) - - FRONT PAGE -

As we age, our bodies un­dergo com­plex changes that, among other things, pro­gres­sively weaken our abil­ity to re­spond to in­fec­tions and de­velop im­mu­nity (this is called i mmunose­nes­cence). That is why dis­eases in older adults tend to be more se­vere, with a greater im­pact on qual­ity of life, dis­abil­ity, and mor­tal­ity, than the same dis­eases in younger pa­tients.

Put sim­ply, aging adults’ im­mune sys­tems need backup. That is where vac­cines come in.

Vac­cines are most of­ten dis­cussed with re­gard to young chil­dren, who should re­ceive a se­ries of in­oc­u­la­tions against child­hood ill­nesses like measles and po­lio. Child­hood vac­ci­na­tions are one of the great­est med­i­cal suc­cess sto­ries of the 20th cen­tury, not least be­cause of so-called herd im­mu­nity (the in­di­rect pro­tec­tion of en­tire com­mu­ni­ties, in­clud­ing those who can­not be im­mu­nised for rea­sons like ill­ness or age, by vac­ci­nat­ing most of their mem­bers).

Noth­ing pro­hibits adults from tak­ing ad­van­tage of the same sci­ence. In fact, they would reap far-reach­ing ben­e­fits – in­clud­ing the pro­tec­tion of their fam­ily and neigh­bors – from do­ing so. Yet few ac­tu­ally do.

Adults need to un­der­stand that some of the more com­mon in­fec­tions to which they are vul­ner­a­ble are vac­cine-pre­ventable. Con­sider shin­gles, an in­fec­tion that can af­fect any­one who has had chicken pox in their life­time (that is, 95% of adults world­wide). In the United States, roughly one-third of the pop­u­la­tion will get shin­gles at some point in their lives.

A case of shin­gles may be be­nign and rel­a­tively bear­able for some­one in his or her thir­ties. But the dis­ease is far more com­mon among peo­ple aged 50 and above – for whom it can be ex­tremely painful. Older adults with shin­gles may ex­pe­ri­ence chronic dis­com­fort and se­ri­ous com­pli­ca­tions that make it dif­fi­cult to sleep, leave the house, or carry out daily ac­tiv­i­ties. If they have been vac­ci­nated – the Cen­ters for Dis­ease Con­trol and Preven­tion rec­om­mends get­ting vac­ci­nated at age 60 – they can avoid this painful, some­times de­bil­i­tat­ing, con­di­tion.

In­fluenza is another vac­cine-pre­ventable dis­ease. While the in­fluenza virus can cause dis­ease in peo­ple of all ages, the el­derly – those 65 and above – are dis­pro­por­tion­ately af­fected, in terms of both death and hos­pi­tal­i­sa­tion, with the old­est be­ing at the great­est risk.

The prob­lem is that older peo­ple are more likely to suf­fer from one or more un­der­ly­ing health con­di­tions, such as heart dis­ease or di­a­betes. As a re­sult, they are also more likely to ex­pe­ri­ence more se­vere in­fluenza-re­lated com­pli­ca­tions. Sys­tem­atic analy­ses among el­derly pop­u­la­tions found in­fluenza vac­ci­na­tion – which must be de­liv­ered an­nu­ally, to ac­count for con­stantly emerg­ing new strains – to be not only suc­cess­ful in pro­tect­ing peo­ple from con­tract­ing in­fluenza, but also cost-ef­fec­tive.

The list does not end there. Diph­the­ria, caused by the aer­o­bic gram-pos­i­tive bac­terium Co­rynebac­terium diph­the­ria, is an acute, toxin-me­di­ated dis­ease that can man­i­fest as an upper res­pi­ra­tory tract in­fec­tion or a skin in­fec­tion. Most com­pli­ca­tions of diph­the­ria – such as my­ocardi­tis (in­flam­ma­tion of the mid­dle layer of the heart) and neu­ri­tis (in­flam­ma­tion of a pe­riph­eral nerve or nerves) – are at­trib­ut­able to the ef­fects of the toxin. The over­all fa­tal­ity rate is 5-10%, with higher death rates among peo­ple younger than five and older than 40.

Tetanus, com­monly known as “lock­jaw,” is a bac­te­rial dis­ease that af­fects the ner­vous sys­tem, caus­ing painful tight­en­ing of mus­cles through­out the body. It does not lead to a very high num­ber of deaths among the el­derly; but, given that it is pre­ventable, any num­ber higher than zero is un­ac­cept­able.

Then there is per­tus­sis. We do not know pre­cisely the ex­tent to which it af­fects the el­derly, be­cause the dis­ease is badly un­der­diag­nosed and un­der­re­ported in all age groups. But the Ad­vi­sory Com­mit­tee on Im­mu­ni­sa­tion Prac­tices thinks that the bur­den of dis­ease is at least 100 times greater than cur­rently re­ported.

The Tdap vac­cine, which pro­tects adults from diph­the­ria, tetanus, and per­tus­sis, could re­duce this bur­den con­sid­er­ably. Another vac­cine, called Td, pro­tects against tetanus and diph­the­ria, but not per­tus­sis. A Td booster should be given ev­ery ten years.

Fi­nally, there is pneu­mo­coc­cal dis­ease, a bac­te­rial in­fec­tion caused by Strep­to­coc­cus pneu­mo­niae, which can cause pneu­mo­nia, menin­gi­tis, or blood­stream in­fec­tion (sep­sis). Depend­ing on which com­pli­ca­tions oc­cur, symp­toms may in­clude cough, abrupt on­set of fever, chest pain, chills, short­ness of breath, stiff neck, dis­ori­en­ta­tion, and sen­si­tiv­ity to light.

Pneu­mo­coc­cal dis­ease can lead to brain dam­age, deaf­ness, tis­sue dam­age (potentially even re­quir­ing the am­pu­ta­tion of limbs), and death. In the US alone, pneu­mo­coc­cal pneu­mo­nia, blood­stream in­fec­tions, and menin­gi­tis kill tens of thou­sands of peo­ple each year, in­clud­ing 18,000 adults aged 65 years and above. Two main types of pneu­mo­coc­cal vac­cine avail­able for older adults – the 23-va­lent pneu­mo­coc­cal polysac­cha­ride vac­cine (PPV23) and the pneu­mo­coc­cal con­ju­gate vac­cine (PCV13) – could ame­lio­rate the sit­u­a­tion.

Thanks to child im­mu­niza­tion pro­grams, fewer chil­dren die each year from vac­cinepre­ventable dis­eases. A sim­i­lar, con­cen­trated ef­fort is now needed to pro­duce sim­i­lar ben­e­fits for adults, es­pe­cially the el­derly. By view­ing vac­ci­na­tion as a life­long pri­or­ity, we can help peo­ple re­main ac­tive and pro­duc­tive for as long as pos­si­ble, ben­e­fit­ing them, their com­mu­ni­ties, and the world.

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