A severe epizootic of Porcine Circovirus Associated Disease (PCVAD) struck swine herds in Eastern Canada towards the end of 2004. Even though many producers implemented better management practices, PCVAD continued to cause severe economic losses for swine producers. During 2006, Circovac® from Merial, Intervet PCV2 vaccine (no trade name), and Ingelvac® CircoFLEXTM from Boehringer Ingelheim became available in Canada. The first reports on the efficacy of piglet vaccines were very positive. De Grau et al. (2007) reported significant reductions in mortality in 4 independent farm trials using PCV2 Intervet vaccine. Desrosiers et al. (2007) also reported similar improvement with Ingelvac® CircoFLEXTM. In a controlled trial done in 4 finisher barns in Quebec in 2006, mortality was 2.4% in vaccinated pigs compared to 9.5% for non-vaccinated pigs. It is obvious looking at these results that piglet vaccination for PCVAD in the finisher stage significantly reduces the impact of this disease on the herd. However, in the initial stages of the outbreak, the supply of piglet PCV2 vaccines was insufficient to meet demand. As a result, many swine production systems used all of the available commercial products concurrently in order to vaccinate as many piglets as possible. Also, off-label use (e.g. half dosing or administering a single injection of vaccines labelled for use as 2 dose vaccines) became a common practice in an attempt to “stretch” vaccine stores and provide protection to the largest possible number of pigs. Field experience so far suggests that fractional (half) dosing can deliver equivalent mortality rates equivalent to full dose schemes but there may be differences in key economic drivers, such as feed conversion (F/C) and Average Daily Gain (ADG). In an attempt to further examine this question the PigCHAMP data from a 3-site production system were analyzed. Based on the data, and within this system, there appeared to be little difference in performance between full vs. ½ dose Intervet PCV2 vaccinated pigs. However, the data was collected in the field rather than under controlled conditions and represent a relatively small number of groups. Clearly what is needed to clarify this picture is information from case-control studies. Additionally, we must not forget that the majority of the vaccine results obtained so far come from herds where better than average management practices and disease control strategies were in place. Therefore, the decision to embark on the use of off label dosing must be made with due consideration for individual herd factors that may influence the results. Ideally, all farms should have an information system in place to collect objective production information that can be used to both benchmark current performance and analyze the impact of management changes (including vaccine regimens). Given the pivotal role that immune stimulation has been demonstrated to play in the expression of PCVAD (Krakowka et al., 2001), it is critical to take the degree of control of other pathogens into account when designing a PCV2 control program. In PRRSv positive groups, the half-dose regimen had the lowest mortality and FC and higher ADG, whereas in PRRSv negative groups, the full dose regimen had the lowest mortality and FC and highest ADG. Unfortunately, because the data came from uncontrolled studies gathered in the field and the sample size was limited, it’s impossible to draw any conclusions at this time but further research aimed at better defining these impacts would clearly be helpful. The complications introduced by circulating PRRS virus also serves to remind us of the importance of controlling circulating primary pathogens. The system in question is currently engaged in actively managing PRRS virus with the goal of eliminating virus circulation. In the opinion of the authors, PCV2 vaccines are the single most effective tool currently available for the control PCVAD. However, some researchers have already started to raise questions about the “immunological cross-protective capability of single-strain commercial vaccines” (Horlen et al., 2007) and to date our understanding of why PCVAD suddenly became a problem within North America is far from complete. We must not allow the effectiveness of PCV2 vaccines to substitute for good management and long term industry wide strategic planning. The next ‘new’ pig disease may be just around the corner and effective vaccines and control strategies may well be a lot further off.