Duba wurin da ke ƙasa sannan ka amsa tambayar daga baya a cikin harshe ɗaya kamar yadda wurin yake:  Passage: Jonas Salk da ƙungiyar a Jami'ar Pittsburgh waɗanda suka haɗa da Julius Youngner, Byron Bennett, L. James Lewis, da Lorraine Friedman ne suka haɓaka rigakafin cutar shan inna ta farko a cikin 1952, wanda ya buƙaci shekaru na gwaji na gaba. Salk ya tafi gidan rediyon CBS don bayar da rahoton gwajin nasara a kan karamin rukuni na manya da yara a ranar 26 ga Maris 1953; kwana biyu bayan haka, an buga sakamakon a JAMA. Farawa 23 Fabrairu 1954, an gwada rigakafin a Makarantar Firamare ta Arsenal da Gidan Watson don Yara a Pittsburgh, Pennsylvania. An yi amfani da rigakafin Salk a cikin gwajin da ake kira Francis Field Trial, wanda Thomas Francis ya jagoranta, babban gwajin likita a tarihi a wancan lokacin. Gwajin ya fara ne da yara 4,000 a Makarantar Firamare ta Franklin Sherman da ke McLean, Virginia, kuma a ƙarshe ya haɗa da yara miliyan 1.8, a jihohi 44, daga Maine zuwa California. A ƙarshen binciken, kusan yara 440,000 sun karɓi ɗaya ko fiye da allurar rigakafin, kusan yara 210,000 sun karɓi placebo, wanda ya ƙunshi kafofin watsa labarai na al'adu marasa lahani, kuma yara miliyan 1.2 ba su karɓi allurar rigakafi ba kuma sun zama rukunin kulawa, wanda za a lura da su don ganin ko wani ya kamu da cutar shan inna.  Tambaya: A ƙarshe, yara nawa ne suka halarci gwajin?
Yara miliyan 1.8