The first is that, when we started trying to eradicate polio about 20 years ago, more than twice as many countries were infected than had been when we started off with smallpox.
Yang pertama adalah, saat kami mulai mencoba memberantas polio sekitar 20 tahun lalu, jumlah negara yang terinfeksi polio lebih dari dua kali lipat daripada jumlah negara yang terinfeksi cacar.