LYNN – Northeastern University nursing student Katie Keppeler said she is studying for a career caring for infants in a neonatal unit.But after three hours Wednesday at a mobile public-health clinic outside City Hall, Keppeler and her fellow students met patients whose needs included calls to numerous drug-treatment programs, trips to the police station and court, and tests for HIV and sexually transmitted diseases.”Working with hospital inpatients, they are often very receptive to the information you provide and the treatment you give,” Keppeler explained. “With this population, you have to meet them where they are – whatever they’re capable of doing at the moment, you provide for them.”Keppeler and five other nursing students from the Bouvé College of Health Sciences at Northeastern University; four nurses from Health Innovations, a public-health services company working with the Department of Public Health; three local outreach workers from the Healthy Streets Outreach Program; and two other lab workers crammed into two campers parked outside City Hall Wednesday to offer free health screenings.Healthy Streets Outreach Program Director Mary Wheeler described the campers as basically mobile health clinics. Anybody can walk up and give their basic information to register. The patient will then go into one of the recreational vehicles and see a nurse and a student who perform a risk assessment and who can give the patient any necessary referrals or set up future appointments. The patient then goes to the lab van to get his or her blood drawn, have a urine screen and undergo any procedures to test for HIV, hepatitis C and sexually transmitted infections.”It can take from 20 minutes to all day,” Wheeler said of the process.The HIV test is “rapid,” offering results quickly. But the other tests require the nurses to follow up with patients, making plans for managing their case and continuing care.But some of the services provided Wednesday demonstrate that public health includes much more than medical tests.Workers provided tutorials on how to recognize the signs of an opioid overdose and how to use the overdose-reversal agent Narcan.Catherine O’Connor, clinical director of Health Innovations, called local detox facilities for a heroin user.Lynn Police Officer Oren Wright stopped by to coordinate with Healthy Streets Outreach workers Denny DesRosiers and Annie DeFranco on accompanying a patient to apply for a restraining order in Lynn District Court.Workers were also prepared to help enroll patients in an insurance plan and offer referrals to everything from mental health care to entitlement programs and immigration services.Meanwhile, the students got practical experience.Wheeler said the mobile health vans travel statewide to service populations who may be at higher risk for certain types of health issues or who may not have regular access to health care.Sometimes this involves parking the vans – one of which is owned by Health Innovations and the other which is from Northeastern – outside trendy gay clubs in Boston. Other times the vans travel to areas with large immigrant populations and/or homeless populations and/or large populations of drug users. The vans travel to Lynn about twice a year, Wheeler said.”It’s right here, right now, you don’t need an appointment,” Wheeler said of the vans. “Some people feel more anonymous not going into an office setting … there are folks we see in other communities who wait for this to come.”Not that everybody’s needs were met. One gentleman walking past saw a patient carrying condoms and approached. The gentleman was reluctant to give his name but replied to the intake question that he had sex with women, then grabbed a few condoms from a jar, got up and moved to the door of the camper.Translating the man’s Spanish, the worker doing intake said the man kept asking for the girls, then assured that he would pay.”What does he think, we’re a brothel?” Wheeler asked.But city resident Craig Man