| 2009 | A(H1N1) Outbreak and Pandemic Milestones |
| 17 March | First case in the world of what would later be identified as swine flu. |
| 28 March | First case in the US of what would later be identified as swine flu. |
| 12 April | First known death due to what would later be identified as swine flu. |
| 24 April | First Diseases Outbreak Notice mention of the Swine Flu by the WHO |
| 27 April | First case confirmed in Canada. |
First case confirmed in Spain. |
First case confirmed in the United Kingdom. |
| 28 April | First case confirmed in Israel. |
First case confirmed in New Zealand. |
| 29 April | First death confirmed in the United States. |
First case confirmed in Germany. |
First case confirmed in Austria. |
| 30 April | First case confirmed in Netherlands. |
First case confirmed in Switzerland. |
First case confirmed in Ireland. |
| 1 May | First case confirmed in Hong Kong, China. |
First case confirmed in Denmark. |
First case confirmed in France. |
| 2 May | First case confirmed in Italy. |
First case confirmed in South Korea. |
First case confirmed in Costa Rica. |
| 3 May | First case confirmed in Colombia. |
First case confirmed in Portugal. |
| 4 May | First case confirmed in El Salvador. |
| 5 May | First case confirmed in Guatemala. |
| 6 May | First case confirmed in Poland. |
First case confirmed in Sweden. |
| 7 May | First case confirmed in Argentina. |
First case confirmed in Brazil. |
First death confirmed in Canada. |
| 8 May | First case confirmed in Japan. |
First case confirmed in Panama. |
| 9 May | First case confirmed in Australia. |
First case confirmed in Norway. |
First death confirmed in Costa Rica. |
| 10 May | First case confirmed in China. |
| 12 May | First case confirmed in Thailand. |
First case confirmed in Cuba. |
First case confirmed in Finland. |
| 13 May | First case confirmed in Belgium. |
| 14 May | First case confirmed in Peru. |
| 15 May | First case confirmed in Malaysia. |
First case confirmed in Ecuador. |
| 16 May | First case confirmed in India. |
First case confirmed in Turkey. |
| 17 May | First case confirmed in Chile. |
| 18 May | First case confirmed in Greece. |
| 19 May | First case confirmed in Paraguay. |
First case confirmed in Taiwan. |
| 21 May | First case confirmed in Philippines. |
| 22 May | First case confirmed in Honduras. |
First case confirmed in Russia. |
| 23 May | First case confirmed in Iceland. |
| 24 May | First case confirmed in Kuwait. |
First case confirmed in United Arab Emirates. |
| 25 May | First case confirmed in Bahrain. |
First case confirmed in Czech Republic. |
| 26 May | First case confirmed in Puerto Rico. |
| 27 May | First case confirmed in Romania. |
First case confirmed in Singapore. |
First case confirmed in Dominican Republic. |
First case confirmed in Uruguay. |
| 28 May | First case confirmed in Bolivia. |
First case confirmed in Venezuela. |
First case confirmed in Slovakia. |
| 29 May | First case confirmed in Hungary. |
| 30 May | First case confirmed in Cyprus. |
First case confirmed in Estonia. |
First case confirmed in Lebanon. |
| 31 May | First case confirmed in Vietnam. |
First case confirmed in Bahamas. |
| 1 June | First case confirmed in Bulgaria. |
| 2 June | First death confirmed in Chile. |
First case confirmed in Luxembourg. |
First case confirmed in Ukraine. |
First case confirmed in Nicaragua. |
First case confirmed in Egypt. |
First case confirmed in Bermuda. |
| 3 June | First case confirmed in Saudi Arabia. |
First case confirmed in Barbados. |
First case confirmed in Jamaica. |
| 4 June | First case confirmed in Trinidad and Tobago. |
| 5 June | First death confirmed in Dominican Republic. |
First case confirmed in Cayman Islands. |
| 7 June | First confirmed case in Martinique. |
| 8 June | First case confirmed in Dominica. |
| 9 June | First death confirmed in Colombia. |
| 10 June | First death confirmed in Guatemala. |
First case confirmed in French Polynesia. |
| 11 June | The WHO raises its Pandemic Alert Level to Phase 6. |
First case confirmed in the Palestinian Territories. |
First case confirmed in British Virgin Islands. |
| 12 June | First case confirmed in Morocco. |