根據政府建議，長期病患、老人最適合打，因他們本身免疫系統弱（即活化B cell變Memory B cell能力也比正常青幼人士弱），他們容易同時受多種肺鏈菌入侵，在平衡風險後，用vP23價可有最大coverage，而且PCV對他們的作用不發用於體能正常的人士身上，所以他們打23價得到的好處比接種7/10/13價這些PCV疫苗更多。
網上睇左呢個終於有D頭緒！我信scientific research多過所謂家庭醫生宣傳！
Abstract
BACKGROUND: A 23-valent unconjugated pneumococcal polysaccharide vaccine (23vP), routinely administered at the age of 65, has limited effectiveness, and revaccination induces attenuated antibody responses. It is not known whether pneumococcal polysaccharide-protein conjugated vaccines (PCV), although highly effective in infants, offer any immunological advantages over 23vP in adults.METHODS: We immunized adults with schedules combining both PCV and 23vP and investigated B-cell responses to establish whether PCV7 (a 7-valent PCV) induced T-dependent responses in adults, to assess the role of memory B cells in 23vP-induced antibody hyporesponsiveness, and to identify the B-cell subtypes involved.RESULTS: A single dose of PCV7 induced significant increases in serotype-specific memory B-cell populations in peripheral blood indicating a T-dependent response. Conversely, immunization with 23vP resulted in a decrease in memory B-cell frequency. Furthermore, memory B-cell responses to subsequent immunization with PCV7, when given after 23vP, were attenuated. Notably, B1b cells, a subset important in protecting mice against pneumococci, were also depleted following immunization with 23vP in humans.CONCLUSIONS: This study indicates that PCV7 may have an immunological advantage over 23vP in adults and that 23vP-induced depletion of memory and B1b-cell subsets may provide a basis for antibody hyporesponsiveness and the limited effectiveness of 23vP. Clinical Trials Registration. ISRCTN: 78768849.
23價係plain polyssccharide vaccine無protein carrier唔似13價係conjugated to protein carrier可刺激memory B cell reponses (大家還記得A level bio教immune system, B cell 和T cell嗎？）。所以接種vP23者的疫苗保護係短暫得幾年，而篇文章最重要一點係指出revaccination of vP23效果仲差，接種左vP23之後再打pcv疫苗（即7、10、13價）亦會削弱pcv疫苗反應！
打23定13，作為家長應自己獨立分析。
我估23價主力推廣老人打，係同時平衡左兩邊風險，23價cover好但效果會慢慢消失，但老人係最high risk targets and their risk will increase with ages! But children will be stronger with increasing ages! That's the difference!
B cell係白血球一種當有antigen（病原體）刺激會產生antibody(抗體）同時在T cell活化下會孌成memory B cell記憶記住隻antigen，下次再遇上會自動極速產生大量抗體抗病。
但係23價冇protein carrier蛋白載體，只可直接刺激B cell產生抗體，而無T cell activate B cell變memory B cell過程，即係身體冇記性去製造抗體，純粹靠第一次接種疫苗刺激而產生嘅抗體去抗病，呢D抗體用哂就冇，臨床證明再接種反應係比第一次弱好多（即係補飛都冇用），之後再打13價亦會大大削弱後者對產生B cell反應。
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