They figured the virus comes from the dead bodies because they haven't buried them. The number of the dead bodies was so huge and they start to bury the bodies. Then. The workers who are bury the bodies has been affect with the same virus because they did not get shot to avoid the disease. Researchers protested because they did not find a solution to the virus. They have done many test but no one without side effect. They have only the one option but the side effect maybe will be more dangerous.