Vaccination plays an important role in preventive healthcare, especially for populations like military personnel, who are at heightened risk of infectious diseases due to their unique environments and exposure levels. This study aimed to evaluate the impact of concurrent vaccinations on the risk of medical encounters in military personnel, considering both deployed and non-deployed groups. We analyze the dataset from 275550 service members, including 179997 deployed and 95553 non-deployed personnel. Using Prentice-Williams-Peterson Counting Process (PWP-CP) model, we assessed the association between various concurrent vaccines (influenza, hepatitis B, anthrax, typhoid, and others) and the occurrence of symptoms such as headache, myalgia, and malaise. Our findings indicated that two or three concurrent vaccines generally reduced the risk of symptoms in the overall and deployed groups. However, receiving four or more vaccines concurrently may slightly increase the risk. These findings suggest that concurrent vaccinations may help mitigate the risk of certain medical symptoms, particularly in deployed personnel, highlighting the need for vaccination strategies within the military context.