is similar to the circulating strain, influenza vaccine is effective in preventing illness among 70‐90% of those younger than 65 years who are vaccinated. Among those aged 65 years and older, the vaccine is 30‐40% effective in preventing illness, 50‐60% effective in preventing hospitalization, and up to 80% effective in preventing death. EMS personnel should be immunized annually, ideally as soon as the vaccine is available locally.
Six licensed prescription influenza antiviral drugs are approved by the U.S. Food and Drug Administration (FDA), four of which (oseltamivir, zanamivir, peramivir, and baloxavir marboxil) were recommended for the 2019‐2020 influenza season. When used for prevention of influenza, they can be 70‐90% effective. However, antiviral agents should be used as an adjunct to vaccination, and not replace it.
The Centers for Disease Control and Prevention (CDC) does not recommend widespread, routine, or pre‐exposure use of antiviral medications for chemoprophylaxis except under specific circumstances [3]. These include short‐term pre‐exposure chemoprophylaxis for unvaccinated health care personnel who are in close contact with persons at high risk of developing influenza complications during periods of influenza activity, when influenza vaccination is contraindicated or unavailable and these high‐risk persons are unable to take antiviral chemoprophylaxis. In addition, there is some weak evidence to suggest that antiviral post‐exposure chemoprophylaxis for unvaccinated EMS personnel can be used during periods of influenza activity when influenza vaccination is contraindicated or unavailable [5, 6]. If post‐exposure chemoprophylaxis is given, it should be administered as soon as possible after exposure, ideally no later than 48 hours. In the setting of an influenza outbreak, EMS systems may opt to restrict duties for EMS clinicians who are not immunized or who have not yet received prophylactic antiviral therapy, in attempts to prevent spread of influenza.
Avian Influenza
Wild birds carry a type of influenza A virus, called avian influenza virus, in their intestines, and usually do not get ill from it. However, avian influenza virus can make domesticated birds, including chickens, turkeys, and ducks, quite ill and can lead to death. Although avian influenza virus is chiefly found in birds, infection in humans from contact with infected poultry has been reported since 1996. A particular subtype of avian influenza A virus, H5N1, is highly contagious and deadly among birds. In 1997 in Hong Kong, an outbreak of avian influenza H5N1 occurred not only in poultry, but also in 18 humans, six of whom died. In subsequent infections of avian influenza H5N1 in humans, more than half of those infected with the virus have died. In contrast to seasonal influenza, most cases of avian influenza H5N1 have occurred in young adults and healthy children who have been exposed to infected poultry, or surfaces contaminated with H5N1 virus.
Although transmission of avian influenza H5N1 from human to human is rare, inefficient, and not sustained, there is concern that the H5N1 virus could adapt and acquire the ability for sustained transmission in the human population. If the H5N1 virus could gain the ability to transmit easily from person to person, a global influenza pandemic could occur. As of June 2020, there were a cumulative 861 cases of human cases of H5N1 reported to the World Health Organization, resulting in 455 deaths. A number of vaccines are currently available for H5N1, the first approved in 2007 and the latest in 2020. Given that the H5N1 virus continually mutates, the best protection for new strains of H5N1 will depend on a vaccine specifically produced for any future virus strain. The H5N1 virus is resistant to the adamantanes, but sensitive to the neuraminidase inhibitors (e.g., oseltamivir, zanamivir) [5].
In April 2009, a novel influenza A (H1N1) virus caused respiratory illness across North America and many areas of the world. The 2009 influenza A (H1N1), while similar to other H1N1 viruses, was genetically and antigenically distinct. Influenza morbidity caused by the 2009 pandemic influenza A (H1N1) remained above seasonal baselines throughout spring and summer and was the first pandemic since 1968. Data from epidemiologic studies conducted during the 2009 influenza A (H1N1) pandemic indicate that the risk for influenza complications among adults aged 19‐64 years who had 2009 pandemic influenza A (H1N1) was greater than typically occurs for seasonal influenza [6].
Avian influenza A (H7N9) virus is a subtype of influenza viruses not previously seen in either animals or people until it was found in China in February 2013. Since its discovery, infections in both humans and birds have been identified. While it has not been reported in birds outside China, its low pathogenicity in birds makes it difficult to identify international spread. Most of the cases of human H7N9 virus infections have reported recent exposure to live poultry or potentially contaminated environments, especially markets where live birds have been sold. Since its discovery, there have been 1,568 confirmed cases and 616 deaths due to H7N9 [7]. The disease is of concern because most people who become infected have become severely ill. This virus does not appear to transmit easily from person to person, and sustained human‐to‐human transmission has not been reported. Asymptomatic and mild infections have been detected, but the underlying rate of such infections is not well understood [8]. There is no current vaccine for H7N9. As with H5N1, neuraminidase inhibitors are effective against H7N9, but adamantanes are not [9].
Tuberculosis
Tuberculosis (TB) is caused by the Mycobacterium tuberculosis complex. The majority of active TB is pulmonary (70%), while the remainder is extra‐pulmonary (30%). Patients with active pulmonary TB will typically present with cough, scant amounts of non‐purulent sputum, and possibly hemoptysis. Systemic signs such as weight loss, loss of appetite, chills, night sweats, fever, and fatigue may also be present. EMS clinicians are unlikely to distinguish pulmonary TB from other respiratory illnesses. However, certain risk factors may alert them to the possibility of tuberculosis. These are immigration from a high‐prevalence country, homelessness, exposure to active pulmonary TB, silicosis, HIV infection, chronic renal failure, cancer, transplant recipient, or any other immunosuppressed state [10, 11]. About half of the world’s TB cases, and two‐thirds of all new cases, come from eight countries: Bangladesh, China, India, Indonesia, Nigeria, Pakistan, Philippines, and South Africa [12, 13].
Active pulmonary TB is transmitted via droplet nuclei from people with pulmonary tuberculosis during coughing, sneezing, speaking, or singing. Procedures such as intubation or bronchoscopies are high risk for the transmission of TB. Respiratory secretions on a surface rapidly lose the potential for infection. The probability of infection is related to duration of exposure, distance from the infected person, concentration if bacilli in droplets, ventilation in the room, and the susceptibility of the exposed person. Effective medical therapy eliminates communicability within 2‐4 weeks of starting treatment [14].
If transporting a patient who is known or suspected to have TB, respiratory precautions should be followed by EMS clinicians, including use of N95 respirators, as these types are necessary for infections that are spread via the airborne route. Patients should cover their mouths when coughing or sneezing or wear a surgical mask. In the event of suspected exposure to a patient with active pulmonary tuberculosis, report the case and the exposure to the EMS system or public health authority. Close contacts should be monitored for the development of active TB symptoms. Two tuberculin skin tests should be performed, based on public health recommendations, on those closely exposed to patients with active TB [15]. Because the incubation period after contact ranges from 2 to 10 weeks, the first test is typically done as soon as possible after exposure, and the second test is typically done eight to 12 weeks after the exposure. If the EMS clinician or contact develops either active TB with symptoms or latent asymptomatic TB, as diagnosed with a new positive TB skin test, treatment should be offered.
There are several treatment regimens for latent TB infection [13]. The CDC and the National Tuberculosis Controllers Association recommend either 3 months of once‐weekly isoniazid plus rifapentine, 4 months of daily rifampin alone, or 3 months of daily isoniazid plus rifampin. Short‐course regimens are effective, safe, and have higher completion rates than traditional 6‐ to 9‐month courses of isoniazid monotherapy. They also have lower risk of hepatotoxicity. For active TB, a four‐drug regimen typically includes isoniazid, rifampin, pyrazinamide, and ethambutol, with an intensive phase of all four drugs daily for 8 weeks, followed by a continuation phase including isoniazid and rifampin daily for an additional 18 weeks [16]. Several forms of multi‐drug‐resistant