Half of gay and bisexual men using PrEP in Australia would
be interested in switching from taking daily PrEP to taking on-demand PrEP, and
this interest was most strongly associated with having sex infrequently and concerns
about long term side effects. The survey was carried out by Dr Vincent Cornelisse and colleagues and is published in the July issue of Open Forum Infectious Diseases.

A total of 970
former PrEPX study participants (almost all gay and bisexual men), were asked
whether they would switch from daily to on-demand PrEP for a new trial. The PrEPX
study was an Australian demonstration study of daily PrEP conducted in Victoria,
South Australia and Tasmania.

On-demand PrEP, also known as event-based PrEP, is when two
PrEP tablets are taken 2 to 24 hours before engaging in sex. Another PrEP
tablet should be taken again 24 hours after the first two tablets, then another
tablet 24 hours later. This was proven to be effective for gay and bisexual men
in the French

Over 5000 former PrEPX participants were sent an email that
explained the concept of on-demand PrEP and contained a link to an online
survey. Approximately 20% responded, with 970 surveys analysed.

Almost half (48%) of those surveyed were interested in
participating in an on-demand PrEP trial.

Interest in on-demand PrEP was associated with having
stopped PrEP, dissatisfaction with daily PrEP, difficulty remembering to take
pills every day, infrequently having sex with an HIV acquisition risk, concerns
about long term side effects from PrEP, and having no prior knowledge of
on-demand PrEP.

Amongst all respondents, current PrEP use was high (86%) while 14% had stopped using PrEP. Reasons for having ceased PrEP included having perceived low HIV risk (54%), concerns about long-term side effects (15%) and ongoing adverse effects (14%).

Of the 970
participants, 116 (12%) reported not being satisfied with daily PrEP, and
reasons for dissatisfaction included concerns about toxicity (27%), infrequent
need for PrEP due to infrequent sexual activity (27%), dislike of taking pills
(20%), difficulty remembering to take pills (16%), kidney problems (5%) and ongoing
adverse effects (4%).

The 501 respondents who were not interested in participating
in an on-demand PrEP study were concerned that on-demand PrEP would be less
effective than daily PrEP (67%). Their other concerns included adherence due to
the strict regimen which is more suitable for planned sexual encounters (58%), feelings
of anxiety about less protection (38%), having spontaneous, unplanned sex (15%)
and having frequent sex and hence needing to take pills every day (2%).

The authors found that interest in on-demand PrEP was
greater in this survey than in previous studies such as the London InterPrEP study,
the Antwerp
demonstration project, and the Amsterdam AmPrEP study. They
recommend that “future Australian studies of on-demand PrEP will need to be
accompanied by education on its relative efficacy, and by adherence supports
that are specifically tailored to this method”.