Vaccine and Treatment Evaluation Unit

The National Institute of Allergy and Infectious Diseases (NIAID) established the Vaccine and Treatment Evaluation Units (VTEUs) in 1962. They provide a ready resource for conducting clinical trials of vaccines and treatments for infectious diseases. 

VTEUs have played a key role in the NIAID effort to develop new and improved vaccines and therapies against infectious diseases for many decades. They have conducted hundreds of clinical trials, many of which have contributed to vaccine licensure.


An important strength of the VTEUs is their ability to enroll large numbers of volunteers into trials rapidly and vaccinate them in a safe, effective, and quick manner. This rapid-response capability is especially important for testing vaccines designed to counteract emerging public health concerns.

For example, the United States experienced an unexpected, significant shortage of seasonal influenza vaccines in 2004. The VTEUs swiftly initiated a large-scale trial to evaluate the seasonal influenza vaccine Fluarix for use in healthy adults in the United States. The trial demonstrated the vaccine’s safety and ability to generate an immune response and ultimately led to its expedited approval by the Food and Drug Administration (FDA) in August 2005—less than a year after the trial began.

The VTEUs conducted multiple studies in 2005 and 2006 of a vaccine for a strain of H5N1 avian influenza virus to determine the most effective dose. Those studies led to the licensure of the first vaccine approved by FDA against an H5N1 influenza virus.

One of the primary goals of NIAID research is to develop new vaccines against infectious diseases, such as pneumococcal infections. The World Health Organization estimates that more than 1.6 million people, including more than 800,000 children under five, die each year from pneumococcal infections. NIAID has invested more than 30 years of research into developing pneumococcal vaccines. Early product development support, as well as Phase I and II studies conducted by VTEU sites in infants, were helpful in developing Prevnar, a vaccine to prevent pneumococcal diseases in children younger than 2 years of age.

Combination vaccines minimize needle sticks and trips to the doctor by delivering more than one vaccine at a time. A five-site VTEU trial evaluated the impact of inactivated (killed) poliovirus vaccine versus oral poliovirus vaccines when given with a combined vaccine against Haemophilus influenza type b, pertussis, diphtheria, and tetanus. As a direct result of the study, health experts now recommend that children get the inactivated poliovirus vaccine as part of their routine immunizations.

VTEUs also test new ways to deliver vaccines. For example, six VTEUs enrolled young children in a Phase III trial of FluMist, an influenza vaccine administered by nasal spray. The vaccine was 93 percent effective against the predominant flu strains of the 1996-97 flu season. In 1998, researchers inoculated the children against three flu strains thought to be circulating that season. The nasal spray vaccine was 86 percent effective against not only the flu strains covered in the vaccine but also against a circulating strain not included in the injected form of the vaccine.

Issues such as lack of refrigeration can make immunizing people using traditional vaccines very difficult in developing countries. Edible vaccines, made from plants, may be an inexpensive and effective way to immunize people in developing countries. The University of Maryland School of Medicine VTEU conducted the first clinical study of an edible vaccine in 1998. Researchers genetically engineered potatoes that, when eaten raw, produced an immune response to Escherichia coli. Scientists have developed genetically engineered plants that contain an antigen for the E. coli bacteria and the Norwalk virus.

In response to concern that smallpox virus could be used as a bioterrorist weapon against the United States, NIAID used the VTEU network to explore the best way to use existing supplies of Dryvax smallpox vaccine to protect military and civilian populations.

Approximately 15 million doses of Dryvax smallpox vaccine have been stored since production stopped in 1983. However, it was estimated that controlling an outbreak of smallpox disease in the United States would require 40 million doses of vaccine. So, in 2002, NIAID began a study to determine whether Dryvax vaccine could be diluted effectively to make more doses of this smallpox vaccine available. The trials showed that the existing U.S. supply of smallpox vaccine could successfully be diluted up to 5 times and retain its potency, effectively expanding the number of individuals it could protect to 75 million.

During the summer of 2009, the VTEUs began clinical trials to evaluate both seasonal influenza vaccines and candidate vaccines for H1N1 influenza. The trials enrolled volunteers of all ages.

These studies will provide information that will help public health officials determine the best vaccination schedule, dosing, and other recommendations. A panel of outside experts conducts a close safety review of all trials to spot immediately any concerns that arise. Results are expected weeks after the clinical trials begin, instead of the usual months or years for a more typical trial.

In 2013, the ability of the VTEU network was expanded to conduct research in domestic and international research locations, including resource-poor settings. This expanded scope will allow researchers to study infectious diseases where they are endemic, enabling them to learn more about the origin and evolution of emerging and reemerging infectious diseases.

Leadership Group and VTEU Sites

In 2019, NIAID established Infectious Diseases Clinical Research Consortium, a clinical trials network that encompasses the VTEUs and a new consortium leadership group. The consortium leadership group will be headed by co-principal investigators David S. Stephens, M.D., of Emory University, and Kathleen M. Neuzil, M.D., M.P.H., of the University of Maryland School of Medicine.

Baylor College of Medicine

Principal Investigator (PI): Hana M. El Sahly, M.D.

Cincinnati Children’s Hospital Medical Center

PI: Robert Wilson Frenck, Jr., M.D.

Emory University

PIs: Nadine G. Rouphael, M.D., Evan J. Anderson, M.D., Carlos del Rio, M.D.

Kaiser Permanente Washington Health Research Institute

PI: Lisa A. Jackson, M.D., M.P.H.

New York University School of Medicine

PI: Mark J. Mulligan, M.D.

Saint Louis University

PI: Daniel Hoft, M.D., Ph.D.

University of Maryland School of Medicine

PI: Karen L. Kotloff, M.D.

University of Rochester

PIs: Ann R. Falsey, M.D., Angela R. Branche, M.D.

University of Washington

PIs: Anna Wald, M.D., M.P.H., R. Scott McClelland, M.D., M.P.H.

Vanderbilt University Medical Center

PI: C. Buddy Creech, M.D., M.P.H.