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Friday, December 8th, 2023

U.S. military recruits still need adenovirus vaccine

The U.S. Department of Defense (DOD) recommends that military recruits entering basic training continue to be inoculated with a vaccine for the adenovirus, a DNA virus considered to be a major cause of febrile illness.

While adenoviruses are usually spread through coughing, sneezing or after touching an infected surface, and rarely cause serious illness or death, the Centers for Disease Control and Prevention (CDC) says that some adenoviruses may spread in bodies of water — such as small lakes or swimming pools without adequate chlorine — and cause outbreaks of febrile disease with conjunctivitis.

Generally, there are two types of adenoviruses — types 4 and 7 — that cause severe outbreaks of respiratory illness, particularly among United States military recruits.

In fact, last February the CDC reported that after 15 years of discontinuation of vaccines for adenovirus types 4 and 7, the department was forced to reinstate oral vaccines against both adenovirus types in November 2011 due to the reemergence of continuous outbreaks of illnesses associated with the virus in American recruit training facilities.

During the two years after reintroduction of the vaccines, military trainees experienced a 100-fold decline in adenovirus disease burden, according to researchers from the Naval Health Research Center, Scripps Research Institute and several universities in a report published in the July 2014 Clinical Infectious Diseases journal.

The researchers estimated that the vaccines prevented approximately one death, 1,100 to 2,700 hospitalizations, and 13,000 febrile adenovirus cases each year among the training recruits.

“These data strongly support the continued production and use of Ad4 and Ad7 vaccines in controlling febrile respiratory illness (FRI) among U.S. military trainees,” concluded the researchers. “Continued surveillance for emerging adenovirus subtypes is warranted.” 

Gaithersburg, Md.-based life sciences giant Emergent BioSolutions Inc. now is developing an updated adenovirus 4/7 vaccine for military personnel under a contract with the DOD to treat adenovirus types 4 and 7, which prior to re-introduction of the vaccine were responsible for an average of three lost training days per trainee, according to the CDC.

“Adenovirus infection presents a risk to the military as it can impact large groups of new recruits housed in close quarters,” Abigail Jenkins, senior vice president and head of the Vaccines and Anti-Infectives Business Unit at Emergent BioSolutions, told Homeland Preparedness News.

Emergent BioSolutions purchased PaxVax, a company focused on specialty vaccines that protect against existing and emerging infectious diseases. Emergent paid $270 million to an affiliate of Cerberus Capital Management L.P. that held a majority stake in PaxVax and included the DOD contract for developing a new adenovirus vaccine.

The adenovirus 4/7 vaccine candidate being developed under contract with the DOD is intended to meet the government’s stated requirement of protecting the U.S. military against those types of adenovirus. The acquisition also included a Phase 2 candidate to address Chikungunya, a viral disease spread to humans by infected mosquitoes that can cause severely debilitating joint pain.

Jenkins said that Emergent BioSolutions plans to improve upon the existing adenovirus vaccine with its candidate, which is now in Phase 1 clinical trials.

“The current vaccine is based on a manufacturing process developed in the 1960s,” she said. “Our modernized vaccine uses modern standard manufacturing equipment; the manufacturing process uses serum-free media, a simplified defined media that reduces potential contaminates and eliminates potential sources of infectious agents.”

A ramped-up adenovirus vaccine could be welcome news for civilians, too, but only if the current HAdV-4 vaccine, registered strictly for use by the military, is expanded.

“At this time, there is not sufficient data to understand the need for a vaccine in the civilian population where most healthy adults, not living in close quarters, are able to protect against adenovirus with their immune system,” Jenkins said. “Civilians at highest risk for complications from adenovirus are those with immunocompromising conditions. Emergent’s adenovirus 4/7 vaccine is designed to reduce the transmission of the adenovirus within a military population. It is based on an unattenuated platform that may not be suitable for general use within a civilian population, especially those who are immunocompromised.”

Over the last several years, 36 cases of HAdV-4 were found near military facilities, according to university researchers in “Adenovirus Type 4 Respiratory Infections among Civilian Adults, Northeastern United States, 2011-2015,” published in the CDC’s February 2018 open access journal, Emerging Infectious Diseases. Lead researcher Adriana Kajon, a scientist in the Infectious Disease Program at the Lovelace Respiratory Research Institute in Albuquerque, N.M., and her team reported that while many of the cases were the common genome types of adenovirus found among military recruits, there were novel variants identified among civilians, as well.

“Specimens came from college students, residents of long-term care facilities or nursing homes, a cancer patient, and young adults without co-morbidities,” according to the researchers, who noted that two novel variants were recovered from students enrolled at a college in Tompkins County, N.Y., and another variant was isolated from an 18-year-old woman visiting a physician’s office in Ulster County, N.Y.

“Our data suggest that HAdV-4 might be an underestimated causative agent of acute respiratory disease among civilian adults,” the researchers wrote. The researchers think the adenovirus was found among these civilians either because the public could have been exposed “to non-attenuated vaccine strains through fecal shedding from military personnel who were vaccinated from 1971 to 1997,” or the strains have been circulating at low prevalence among civilian communities since the virus was discovered in the 1950s. The university researchers recommended in the CDC report that the HAdV-4 vaccine now be made more widely available.

“On the basis of the severity of the clinical presentation of some cases in this study, the HAdV-4 vaccine currently licensed for military use should be considered a potentially valuable resource to prevent disease in susceptible populations living in closed communities, such as college settings, summer camps, and long-term care facilities,” wrote Dr. Kajon and her research team.

That also could help in situations in which the CDC says people with weakened immune systems, or those having existing respiratory or cardiac diseases, are at higher risk of developing severe illness from an adenovirus infection.

That’s what happened when an adenovirus 7 viral outbreak occurred last year at the Wanaque Center for Nursing and Rehabilitation in Haskell, N.J., killing 11 children.

The center is contesting federal investigators’ findings in a 114-page report compiled by the New York regional office of the Centers for Medicare and Medicaid Services showing a lack of administrative oversight, slow responses from medical staff and a flawed infection-control plan.

Currently, the CDC says there are at least 60 strains of the contagious adenovirus with no vaccine for the general public available, leaving supportive care as the best treatment.