ワクチン効果、高齢・喫煙で減　毎日の飲酒も影響―６０～７０代は２０代の半分

　全国民の過半数が２回接種を終え、３回目も実施の方向となった新型コロナウイルスワクチン。接種が行動制限緩和の条件になる一方で、高齢者や喫煙者、毎日飲酒する人では効果が低下しやすいとの報告も出ている。ただ、専門家は「高齢者など重症化リスクが高い人たちこそ、ぜひ接種を」と訴える。
　国立病院機構宇都宮病院（宇都宮市）は、米ファイザー製ワクチンの接種を受けた職員３７８人について、感染を防ぐ中和抗体の量や強さを示す「抗体価」を分析。２回目接種から３カ月後の中央値をみると、６０～７０代の男女と５０代男性は２０代の約半分にとどまった。５０代女性も６割程度で、年代が上がるほど抗体価は下がる傾向が出た。
　また、喫煙歴がない人は全体の中央値より約１２％高かった。一方、喫煙歴がある人は約２３％、喫煙者は約３５％、それぞれ低かった。
　杉山公美弥副院長は「高齢者は免疫細胞の働きが加齢で少しずつ弱まるため、接種により作られた抗体が十分に維持できないのでは」と指摘。「肺には多くの免疫細胞が集まり、全身の免疫と直結する。たばこの煙で肺の免疫細胞がダメージを受け、抗体量が維持できない」と分析する。
　千葉大病院（千葉市）は、ファイザー製を２回接種した職員１７７４人を調査。抗体価は女性の方が高く、高齢者や毎日飲酒する人、免疫抑制剤の服用者は低かった。特に酒は、飲まない人と比べ週２～３回飲む人は差がないが、毎日飲む人は約２割低かった。
　国立感染症研究所の脇田隆字所長は、こうした傾向について「高齢者や喫煙者などは重症化しやすい。抗体価が上がりにくいとしても、接種を積極的に受けることは大事だ」と強調。国の担当者も「接種は受けてもらいたい。（抗体価への影響に関する）知見についても専門家と相談して発信したい」と話す。（2021/09/19-07:12）

While Japan plans to start "booster" shots of novel coronavirus vaccines for people who have been inoculated against COVID-19 twice, studies have shown that the efficacy of the vaccines tends to fall among the elderly and people who smoke and drink.
   With over half of Japan's population having completed their two shots, the government is looking at the possibility of making vaccinations a prerequisite for relaxing restrictions on activities, so maintaining the efficacy of the inoculations is important.
   The National Hospital Organization Utsunomiya Hospital tested 378 staff members who had received the vaccine developed by U.S. drugmaker Pfizer Inc. for their antibody titer, or the amount and strength of neutralizing antibodies, three months after their second shots.
   The test showed that the vaccine efficacy decreases with age. Specifically, the median levels of antibody titer in people in their 60s and 70s, and men in their 50s were only about half of those for people in their 20s. For women in their 50s, the levels stood at around 60 pct of those for people aged 20-29. The median levels for people who have not smoked were about 12 pct higher than those for all people tested, while the levels for past and current smokers were lower by some 23 pct and 35 pct, respectively.
   "Elderly people may not be able to sufficiently maintain antibodies produced by vaccinations as their immune cells weaken with age," Kumiya Sugiyama, deputy head of the hospital in Utsunomiya, the capital of the eastern prefecture of Tochigi, said, adding, "Many immune cells are in the lungs and directly connected to the immune system of the whole body, so smoking damages the immune cells in the organ, making it difficult (for smokers) to maintain antibody levels."