If you’re among the more than 200,000 service members and veterans participating in the long-term health study, researchers are calling on you to fill out a follow-up survey, as they track health risks of deployment, military occupations and general military service.

This Department of Defense Millennium Cohort Study began in 2001, with 77,047 participants invited based on scientific random sampling methods. The study is part of the Deployment Health Research department, at the Naval Health Research Center. Visit https://millenniumcohort.org if you are one of the service members/veterans who are part of this study. You’ve probably gotten an email or postcard notifying you about the survey, which takes about 30 to 40 minutes.

Over the years additional participants have been added, but new participants aren’t being added this year. The next new group is expected to be added in 2022, according to John Marciano, spokesman for the Naval Health Research Center.

This portion of the study will be open for about a year, Marciano said, depending on the participation rates. The responses are anonymous; participants are encouraged to continue in the study after they leave the military. The study will follow participants through at least 2068.

It’s the largest and longest-running health study of military personnel. This is in addition to other DoD surveys that track similar issues through surveys with different random scientific samplings every several years. The Millennium Cohort Study tracks health effects by following the same service members and veterans over the long term.

About 61 percent of the current cohort have deployed to Iraq and Afghanistan; 42 percent are veterans; 31 percent are women; and 44 percent are members of the Reserve or National Guard.

Results from the surveys help improve military readiness and protect the health of service members and veterans, officials said.

The research from these surveys has resulted in dozens of studies on a variety of topics related to service member and veteran health, such as respiratory health after military service in southwest Asia and Afghanistan; links between post traumatic stress disorder symptoms and subsequent problem drinking; and sleep patterns before, during and after deployment to Iraq and Afghanistan, to name a few.

Generally, those who participate complete a survey about every three years. They answer questions about their general health and well-being; their health behaviors such as alcohol and tobacco use, eating behaviors, sleep, physical activity; their health conditions and symptoms such as diagnosed medical conditions, physical symptoms, mental health assessments and pregnancy and infertility; use of health care and preventive care; potential exposures such as combat experiences, injuries, burn pits and assault; military life such as status, deployments, occupation, perception of the military; and other topics such as employment, education, homelessness and stressful events such as financial problems or divorce.

The study was recommended by Congress and the Institute of Medicine in 1999, in response to concerns about the health effects of deployments following the 1991 Gulf War -- before the post-9/11 conflicts.

“Although the original designers of the Millennium Cohort Study could not foresee the post-2001 military conflicts, the project is perfectly positioned to address health outcomes related to these operations,” according to the Millennium Cohort Study website.