Yellow fever Brazil. In March 2018, Brazil shifted its policy and announced it planned to vaccinate all 77.5 million currently-unvaccinated citizens by April 2019. Some countries in Asia are theoretically in danger of yellow fever epidemics (mosquitoes with the capability to transmit yellow fever and susceptible monkeys are present), although the disease does not yet occur there. To prevent introduction of the virus, some countries demand previous vaccination of foreign visitors if they have passed through yellow fever areas. Vaccination has to be proved by the production of a vaccination certificate which is valid 10 days after the vaccination and lasts for
1793 Philadelphia yellow fever epidemic the personal letters, which are largely held by Quaker colleges in the area. While Powell did not write a scholarly history of the epidemic, his work reviewed its historical importance. Since the mid-twentieth century, scholars have studied aspects of the epidemic, first in papers. For example, Martin Pernick's "Politics, Parties, and Pestilence: Epidemic Yellow Fever in Philadelphia and the Rise of the First Party System," developed statistical evidence to show that Republican doctors generally used Rush's therapies and Federalist doctors used Kuhn's. Scholars celebrated the 200th anniversary of the epidemic with the publication of papers on various aspects of the