This is the release from the uniting church on why they cancelled:

"City Church Locations
Ross Memorial – cnr Hay & Colin Streets, West Perth Trinity - 72 St Georges Terrace, Perth
St Andrews – cnr St Georges Terrace & Pier Street, Perth Wesley - 93 William Street, Perth
Cancelation of Australian Vaccination Network event
The Uniting Church in the City (UCIC) is a group consisting of members of four innercity
church congregations and has a number of venues which are made available for
public use as part of the Church’s commitment to creating a vibrant civil society within
the City of Perth.
The UCIC has decided to cancel the hire of one of its rooms at the Queen's Building by
the Australian Vaccination Network (AVN) tomorrow evening, Friday 14 May 2010.
The AVN was due to hold a seminar at the UCIC rooms in relation to the flu vaccine.
However, since the booking of the rooms by the AVN, the UCIC has received a number
of communications from members of the Uniting Church and other interested persons
which has raised serious concerns within UCIC about the hiring of the rooms to the
AVN.
One of the UCIC's concerns is that there may be a public perception that the UCIC does
not support childhood vaccinations, due to the AVN seminar being held at UCIC's
rooms. In addition, the level of public response has raised security concerns for other
users of the Queen's Building, which the UCIC would wish to avoid.
In addition, the level of public response has raised security concerns for other users of
the Queen’s Building in which the event was due to take place.
In the light of this, the UCIC has made the decision to cancel tomorrow’s event so
these issues can be discussed and resolved in a thoughtful manner.
We would like to apologise for any inconvenience this has caused to the AVN."