The national Aids Trust has accused the Government of not doing enough to fight discrimination in schools against pupils and teachers who have HIV.
An investigation by the trust found several cases where children have been refused places or temporarily excluded and where teachers have been forced out of jobs.
The charity met officials from the Department for Children, Schools and Families last week to try to hammer out a deal that will see the department issue health and safety advice to schools.
It is understood that ministers are still reluctant to commit to a course of action, despite most of the main teaching unions throwing their weight behind the initiative.
Deborah Jacks, the trust's chief executive, said its campaign began more than 18 months ago, but it got an appointment with the Government only last month.
"There has been very little pro-active response from the Government on the issue," Ms Jacks said.
"Schools and all public bodies have a duty to promote equality, and under the Disability Discrimination Act, it is illegal to discriminate against people with HIV.
"We want teachers to realise there is no risk of children being able to infect other children or teachers with the disease. And there have been no known cases of it happening elsewhere in the world," she said.
The main aim of the campaign is to try to educate teachers, schools and parents about the level of risk involved and to remove any confusion that surrounds the virus.
"The only information currently available is on teachernet.gov.uk, which actually reinforces the problems, telling teachers which classes children with HIV can't take part in. They should be allowed to take part in every class," Ms Jacks said.
In a letter to the department, the National Association of Head Teachers, the NASUWT and the Association of Teachers and Lecturers said they wanted to see more commitment from the Government to issue better advice.
"It would, we suggest, be a simple matter to send information to all headteachers outlining their duties around HIV under the Disability Discrimination Act, reiterating that they cannot discriminate against a child because they are HIV-positive, and providing guidance on how they can ensure they are operating fair policies and practice," the unions wrote.
A spokesman for the DCSF said after last week's meeting with the National Aids Trust to discuss the guidance issued to schools: "We are engaged in ongoing dialogue about how we can update the information available to schools on our Teachernet website."