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Andrew Moon, MD, MPH

Outbreaks of hepatitis A, a highly contagious viral infection involving the liver, have been on the rise since 2016. What initially began as outbreaks in a handful of states has since led to ongoing or recent hepatitis A outbreaks in 33 states across the country.

Patients under the care of the Veterans Health Administration have been one of the hardest-hit groups. This is because Veterans Health Administration (VHA) hospitals treat a number of homeless veterans, as well as a substantial number of veterans with HIV, hepatitis C infection, or liver cirrhosis, who have the greatest risk of contracting or developing complications of hepatitis A.

In response to the recent outbreaks, Andrew Moon, MD, MPH, an assistant professor of medicine in the Division of Gastroenterology and Hepatology in the Department of Medicine, has been working with investigators affiliated with Veterans Affairs hospitals throughout the United States to better understand vaccination response rates across states with outbreaks and those without any outbreaks at all.

They discovered a 112% increase in hepatitis A vaccines in outbreak states in the year following the outbreak, demonstrating that the VHA acted both efficiently and effectively to provide much-needed protection to veterans.

“Overall, these were really encouraging findings that the VHA is able to carry out these well-coordinated vaccination campaigns in response to infectious disease outbreaks, said Dr. Moon. “I think the lessons from other infectious diseases like hepatitis A, and from large health care organizations like the VHA, can be applied to help address future infectious disease outbreaks.”

The findings were published in the American Journal of Public Health in June.

Hepatitis A is a virus that can cause inflammation of the liver. It is spread through food, water, and person-to-person transmission. It usually results in a mild acute infection characterized by fatigue, nausea, and jaundice. Occasionally, the viral infection can result in liver failure and death.

Fortunately, the infection can be prevented with a vaccine. The vaccine’s efficacy has been widely documented and it is quite effective. The vaccine is administered in a two-dose series and has an efficacy of around 95%. Researchers know the vaccine provides protection for at least two decades, if not longer.

But vaccines are only as effective as the campaigns that get them into patients’ arms.

So, Dr. Moon and a group of VHA officials got together and picked four outbreak states: Florida, Kentucky, Indiana, and Washington, all of which had current statewide outbreaks at the time of the study. They then created a comparison group of four non-outbreak states: Texas, Maryland, Wisconsin, and Oregon. They chose these states because they are in the same region as the outbreak states and are of similar size.

After narrowing in on their research locations, they then collected data about vaccine responses, the number of high-risk veterans who received the vaccine, and predictors of how many people received the hepatitis A vaccine.

In response to hepatitis A outbreaks, there was an astonishing 112% rise in hepatitis A vaccinations in outbreak states throughout the duration of the research, compared to the year before; yet, hepatitis A vaccination rates in non-outbreak states remained relatively consistent over this time.

This demonstrated that the rise in outbreak states was more than a passing trend; it was most likely the outcome of hepatitis A outbreaks, which prompted a concerted reaction and an increase in hepatitis A vaccines. Overall, the increase in hepatitis A immunizations was greatest among high-risk individuals.

At the end of the study, they then identified the number of vulnerable individuals who remained unvaccinated.

They discovered that half of those who were homeless were still unvaccinated, and nearly a third of those with cirrhosis of the liver were also unvaccinated. Additionally, when compared to white veterans, Black, Native American, multi-racial, and Hispanic veterans were less likely to receive the vaccination.

“Overall, the findings were very encouraging,” said Dr. Moon. “But we did see some disparities in the receipt of vaccination. I think this study also identified some areas where we could improve.”

With such a strong response to the statewide hepatitis A outbreaks, Dr. Moon believes that other infectious disease specialists can learn from this experience and use these results to think of better ways to encourage vaccinations and to avoid or decrease future infectious disease outbreaks.