Information for Providers and Victims

From CDC - What is a crowded group setting?
For planning purposes, public health officials can consider a housing situation with more than 100 persons "crowded."  However, this is not a firm rule; it is influenced by public health resources and the layout of the shelter, among other factors.  The intent of the recommendation to vaccinate persons in crowded settings was to prevent outbreaks that would take additional time and resources to detect, control and treat disease, or that might get out of control before detected. 

Local officials should exercise their own judgment in evaluating local conditions.  For example, in a setting with very limited public health capacity, there may be benefit in vaccinating in a shelter with fewer than 100 residents, especially if they have close contact.  In a shelter with 100 or more residents that has limited likelihood of transmission (for example, if residents are housed 4 to a dormitory-type room), it may be reasonable to not apply this guideline. 

Priority should be given to offering vaccination to residents of the largest group shelters with persons housed in large rooms with many other people (for example, stadiums and convention centers) before moving on to smaller shelters.

From CDC - Hepatitis A: Larger shelters present more opportunities for introduction of hepatitis A, and larger post-exposure immunoprophylaxis challenges if a case is identified. Several families in one home would not be a typical situation where hepatitis A vaccination would be recommended. However, local circumstances can be taken into consideration. State health departments and agencies, as well as other Federal agencies, can and have made their own recommendations.  The CDC recommendations need not be interpreted as overriding other recommendations. The CDC recommendations are based on a careful consideration of what is known about hepatitis A epidemiology.