How Long Is Pneumonia Contagious? Bacterial pneumonia becomes less contagious when a sick individual has taken antibiotic treatment for about 1-2 days. However, for some bacteria, such as those causing tuberculosis, it may take at least 2 weeks of treatment before a person becomes less contagious. People with viral pneumonia become less contagious after their symptoms recede. However, coughing may persist for several weeks even if one is not contagious anymore.