Carlos Gregorio Hernandez Vasquez, 16, “is seen lying on the floor, vomiting on the floor, and walks over to the commode, where he sits and later lies back and expires.” This is how Norma Jean Farley, a contract forensic pathologist for Hidalgo County, Tex., described this Guatemalan boy’s last moments in her autopsy report, after she reportedly reviewed a video from the detention facility. The autopsy attributed the death to the virus responsible for 3,000 to 49,000 U.S. deaths each year: influenza.

Carlos had crossed the border alone near Weslaco, Tex., on May 13 and was held at a processing center in McAllen, where he developed a high fever on May 19. He was dead by 6 the next morning. He was the third migrant child to die after being detained by U.S. Customs and Border Protection (CBP) since December 2018 whose death was at least partly attributed to influenza.

Yet CBP does not plan to provide influenza vaccine to migrants in its custody this flu season. A CBP spokesperson provided the reason: “In general, due to the short-term nature of CBP holding and the complexities of operating vaccination programs, neither CBP nor its medical contractors administer vaccinations to those in our custody.”

This policy is not just cruel to the migrants who might become sick while in custody. It’s also unwise from a general public health perspective. The Trump administration’s decision could make wider flu outbreaks more likely.

The influenza virus is primarily spread through droplets that are made when people with flu cough, sneeze or even talk. These droplets can infect someone nearby by landing in their mouths or noses or after being inhaled into the lungs. Some people get infected by coming into contact with a surface that has the influenza virus on it and then touching their face or their eyes.

Situations where people live close to one another increase the risk of infectious diseases — particularly respiratory infections such as influenza. Although there is limited research on the risk of influenza in CBP detention facilities specifically, data from jails or prisons can serve as a useful guide. Such institutions also have transient populations living in conditions that result in high rates of contact between inmates and with facility staff members. These conditions result in a higher risk of outbreaks.

The influenza vaccine is not perfect, but it is the most useful tool available to reduce influenza risk — not just among incarcerated or detained people, but also among facility staff members, such as CBP officers or contract guards. The decision not to vaccinate the detainees may affect CBP’s workers and their ability to perform their duties. And, of course, if detention facility staff members are infected with flu, they can spread the virus to the wider community.

Suboptimal influenza vaccination rates among institutionalized people are not unique to CBP facilities. In a study, my colleagues and I found that 55 percent of correctional facilities reported not receiving any influenza vaccine during the 2009 pandemic. The pattern is similar for the seasonal influenza vaccine. Sure enough, several influenza outbreaks have occurred among institutionalized populations in the United States. For example, in 2011, there were influenza outbreaks in two correctional facilities where fewer than 10 percent of inmates were vaccinated. The outbreaks resulted in a death at one of the facilities.

Vaccinating people in CBP custody is even more important now than in the past, because of the higher proportion of children among those crossing the U.S.-Mexico border. Although the influenza vaccine is recommended for anyone older than 6 months, children and the elderly disproportionately suffer from severe adverse outcomes if they get the flu.

Besides an overall increase in border crossings from Mexico in recent years, these crossings follow a seasonal pattern, with more crossings in early spring and a substantial decrease in crossings during the summer. The annual flu season in the United States tends to run from October to May, peaking between December and February. That means there is an overlap between the seasonal increase in border crossings and increased influenza activity in the United States. It is possible, if not likely, that the decision not to vaccinate CBP detainees could result in additional cases of influenza-related illnesses, hospitalizations and even death in coming months. Increased circulation of the influenza virus in detention facilities also could result in additional risk to CBP personnel. Even if humanitarian concerns don’t change the policy, CBP should reconsider simply on pragmatic — and epidemiologic — grounds.

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