Coinfection with COVID-19 and influenza was reported early in the pandemic. Although both infections on their own can cause severe complications and death, coinfection can double the odds of death when compared with COVID infection alone. Moreover, those odds can be raised by chronic medical conditions and environmental or occupational factors, such as congregate living settings, say physicians who report on the first 2 confirmed cases of COVID-19 and influenza coinfection among US Department of Defense personnel within the US Central Command area of responsibility.
In the first case, a 56-year-old contractor presented to a Role I clinic with anorexia, fever, chills, and headache, which had begun 3 days before. His initial vital signs were “unremarkable,” and he did not have symptoms of respiratory distress. An antigen test was positive for influenza type A. A COVID-19 test also was positive. He was placed on isolation and treated with oseltamivir, amlodipine, hydrochlorothiazide, and losartan. His condition did not warrant hospitalization. Of 3 close contacts, 1 tested positive and was isolated. Two remained asymptomatic during the 14-day quarantine. Ten days after onset, the patient returned to duty.
The second patient, a 34-year-old officer in the Army, was initially identified as a close contact of a confirmed COVID-19 case and placed in quarantine. He was asymptomatic but tested positive and was placed in isolation with precautions. As with the first patient, his vital signs were unremarkable. He continued to be asymptomatic, although he reported myalgias 2 days later. Since those are a classic sign of seasonal influenzas, he was tested and proved positive for type B influenza. He, too, was started on oseltamivir. By the end of the first week, he experienced loss of taste and smell, cough, and shortness of breath, but his vital signs remained normal. His symptoms improved through supportive care. All 6 of his close contacts remained asymptomatic. Ten days after his symptoms began, he also returned to duty.
Influenza-associated deaths among the US military have been relatively few, the authors say, most likely because of the good preexisting health status of the US military, prompt detection with rapid influenza diagnostic tests, several effective antiviral therapeutics, and a “robust, compulsory vaccination program.” Nonetheless, neither patient had received the 2020-2021 influenza vaccine, which underscores the importance of this intervention, the authors say.
Because both infections present with a wide variety of clinical manifestations and overlapping symptoms, providers should stay alert to the possibility of coinfection, especially among personnel who are higher risk. For instance, as a linguist who interacted daily with host nation partners, the civilian contractor had a high occupational exposure.
While the authors only discuss 2 cases, a Medical Surveillance Monthly Report editorial comment says their report “nevertheless supports the importance of implementing force health protection (FHP) measures to prevent, detect, and respond to the spread of both of these health threats.” It’s particularly important, the comment notes, in the current context of a drawdown in forces in many deployed locations, as further losses of personnel to illness may degrade the execution of critical missions.