蓋茨的資金主要通過(guò)全球根除小兒麻痹癥計(jì)劃發(fā)揮作用，目前這種可怕的疾病已接近根除,，全球只有阿富汗和巴基斯坦兩國(guó)野外仍有脊髓灰質(zhì)炎病毒活躍,。1988年還有125個(gè)國(guó)家出現(xiàn)病例,。

根除疾病的任務(wù)跟基金會(huì)幾乎所有項(xiàng)目一樣,，運(yùn)作成熟且由數(shù)據(jù)驅(qū)動(dòng)。蓋茨資助疾病監(jiān)控人員經(jīng)在熱點(diǎn)地區(qū)污水系統(tǒng)中抽樣檢查,，看是否有潛伏的脊髓灰質(zhì)炎病毒,，然后利用數(shù)字衛(wèi)星數(shù)據(jù)了解特定地區(qū)兒童數(shù)量，從而計(jì)算接種推廣小組要走訪多少家庭,。

基金會(huì)還花費(fèi)超過(guò)十億美元,，減輕古老且長(zhǎng)期被忽視的熱帶疾病（NTDs）造成的負(fù)擔(dān),，相關(guān)疾病可能引發(fā)失明,、貧血到四肢腫脹等。盡管取得了進(jìn)展,，但仍導(dǎo)致地球七分之一的人口患病,。基金會(huì)強(qiáng)化了發(fā)展中國(guó)家的衛(wèi)生系統(tǒng),，也不斷推動(dòng)農(nóng)業(yè)創(chuàng)新,。（比爾在搞怪又樂(lè)觀的蓋茨筆記博客上有一篇博文開(kāi)頭寫(xiě)道，“我從不掩飾對(duì)化肥的熱情,?！保?/p>

基金會(huì)還在美國(guó)發(fā)起了全國(guó)性關(guān)于教育改革的對(duì)話(huà)，背后有數(shù)據(jù)支持,，也有大量投入的資金支持,。（基金會(huì)每年花費(fèi)3億美元用于K-12學(xué)習(xí)，也在推廣高效學(xué)習(xí)法,。）蓋茨夫婦還改變了家庭慈善事業(yè)的性質(zhì)和規(guī)模,，2010年與沃倫·巴菲特合作，說(shuō)服其他億萬(wàn)富翁在有生之年或在遺囑里捐出至少一半財(cái)產(chǎn),。如今已有近200個(gè)家庭加入了名副其實(shí)的“捐贈(zèng)誓言”,。

“他們每個(gè)舉動(dòng)都會(huì)產(chǎn)生乘數(shù)效應(yīng),，”有一次電話(huà)采訪中，沃倫·巴菲特如此評(píng)價(jià)蓋茨夫婦,，數(shù)十年來(lái)巴菲特一直是蓋茨夫婦的好友,。后來(lái)他向蓋茨基金會(huì)捐贈(zèng)了50萬(wàn)股伯克希爾·哈撒韋的B股，當(dāng)時(shí)價(jià)值約16億美元,，從此自己的財(cái)富也實(shí)現(xiàn)了乘數(shù)效應(yīng),。

“他們每個(gè)舉動(dòng)都會(huì)產(chǎn)生乘數(shù)效應(yīng)。兩人行動(dòng)目標(biāo)一致,?！薄謧悺ぐ头铺兀讼枴す鲰f董事長(zhǎng)兼首席執(zhí)行官,。

但是比爾和梅琳達(dá)·蓋茨的影響還不只在金錢(qián)方面,。巴菲特提到了之前的想法：“他們夫婦倆也有乘數(shù)效應(yīng)，合在一起力量大,。兩人的行為目標(biāo)一致,，只是做事風(fēng)格不一樣，”他說(shuō),，一邊為自己一針見(jiàn)血指出本質(zhì)笑起來(lái)： “他們直接就來(lái)找我,，就這么簡(jiǎn)單?！?/p>

“他們很注重結(jié)果,，大多數(shù)人都不知道如果沒(méi)有他們堅(jiān)持，很多事都不會(huì)發(fā)生,，”U2主唱博諾表示,。他和蓋茨夫婦一樣堅(jiān)持推動(dòng)全球醫(yī)療衛(wèi)生進(jìn)步，發(fā)起的(RED)基金和ONE運(yùn)動(dòng)都獲得了基金會(huì)資助,?！皬奈业牧私鈦?lái)看，他們對(duì)收入的唯一興趣只在于能改變其他人的生活,，”他補(bǔ)充說(shuō),。“他們不求認(rèn)可,，只是不斷堅(jiān)持做事,。就好比，他們搭好攝影棚又找好了攝影師,，但太注重結(jié)果,，有時(shí)有忘了讓自己出鏡。”

過(guò)去20年里,，他們工作幫助改變了數(shù)億人的生活,。如果現(xiàn)在資助的研究能幫助預(yù)防治療艾滋病、耐多藥結(jié)核病,、瘧疾,、被忽視的熱帶疾病和流感，還能多影響數(shù)十億人,。如果提升婦女權(quán)力,、提供衛(wèi)生設(shè)施、促進(jìn)農(nóng)業(yè)和教育（以及提供教育機(jī)會(huì)）的工作獲得理想的結(jié)果,，造福世界更是無(wú)可估量,。

正因如此，《財(cái)富》雜志將比爾和梅琳達(dá)·蓋茨選入2019年全球最偉大領(lǐng)袖名單,。說(shuō)實(shí)話(huà),，入選只是一次，但兩人的領(lǐng)導(dǎo)能量絕對(duì)是雙倍的,。

The Gates money, put to work through the Global Polio Eradication Initiative, has helped bring that horrific paralyzing disease to the brink of elimination, leaving only two places on the earth, Afghanistan and Pakistan, where the wild poliovirus remains active. In 1988, the disease could be found in 125 countries.

The eradication quest is, as nearly all foundation efforts are, sophisticated and data-driven. Gates-funded disease hunters have plumbed sewage systems in hotspot regions to check for lurking poliovirus and used digital satellite data to understand how many kids were in a given area—and, therefore, how many houses inoculation teams needed to visit.

The foundation has spent more than a billion dollars to date to reduce the burden of ancient, and long neglected, tropical diseases (NTDs) that can cause everything from blindness to anemia to an elephantine swelling of limbs—and that, despite the progress made, continue to debilitate one-seventh of the earth’s population. It has fortified health systems in developing countries and brought new innovations to agriculture. (As Bill begins one of his wonkily upbeat GatesNotes blogs, “I’ve never been shy about my passion for fertilizer.”)

The foundation jump-started a national conversation in the U.S. on education reform: one backed by data, as well as dollars—though there have been many of those, too. (It spends $300 million annually on K-12 learning, and on learning about learning.) The Gateses have even changed the nature and scale of family philanthropy—partnering with Warren Buffett in 2010 to convince other billionaires to give half or more of their money away during their lifetime or in their will. Today, nearly 200 families have joined the aptly named “Giving Pledge.”

“Every one of their actions has a multiplier effect,” says Warren Buffett in a phone interview about the pair, with whom he has been close friends for decades. His own fortune became part of that multiplication as well, when he donated 500,000 Berkshire Hathaway B shares to the Gates Foundation—a gift then worth about $1.6 billion.

“Every one of their actions has a multiplier effect. They act with a unity of purpose.” – Warren Buffett, Chairman and CEO, Berkshire Hathaway

But the impact of Bill and Melinda Gates is due to more than money. Buffett returns to his earlier thought: “The two of them have a multiplier effect—the two of them together. They act with a unity of purpose and with a difference of style,” he says, chuckling at the truth of his own line: “That just came to me—and it’s really true.”

“They are so results-orientated that most people have no idea all the things that would not be happening without them,” says Bono, who, like the Gateses, has been a tireless champion for global health, and whose own (RED) and ONE campaigns have received funding from the couple. “For as long as I’ve known them, their only interest in their income is the outcomes it can generate for others in terms of changing lives,” he adds. “They don’t ask for acknowledgment; they just get on with it. They set up the scene, hire the photographer, but are so focused on results, they sometimes forget to be in their own photograph.”

Their work over the past 20 years has helped transform the lives of hundreds of millions of people—and will surely affect billions more if the research they’re funding now helps prevent and cure AIDS, multidrug-resistant TB, malaria, neglected tropical diseases, and the flu. It will help immeasurably more if the work they’re doing now to empower women, provide sanitation, boost agriculture, and improve education (as well access to education) comes to full fruition.

For all that, Fortune has chosen Bill and Melinda Gates as our 2019 World’s Greatest Leader. The pick, pointedly, is a singular one; the power of their leadership is definitely double-barreled.