Circovac

Circovac is a vaccine for use in pigs. It comes in two vials, one containing a suspension and the other containing an emulsion, and these need to be mixed before injection. Circovac contains an inactivated porcine circovirus type 2 (PCV2) virus strain. ‘Inactivated’ means that the virus has been killed so that it can no longer cause disease.

Circovac is used to reduce the changes in and damage to lymphoid tissues associated with PCV2 infection in piglets and to help reduce the overall deaths in piglets connected with this infection. The vaccine is given to female pigs before and/or during pregnancy. Their piglets then become immunised when they drink the colostrum (first milk) from their vaccinated mothers.

Circovac is given by deep intramuscular (into a muscle) injection. The number of injections needed varies according to the type of female pig being treated: gilts (female pigs that have not yet had piglets) need to receive three injections; sows (female pigs that have had piglets before) need to receive two injections; and sows that have been vaccinated before need only one injection. The timing of the injection is adjusted according to the dates of mating and farrowing (giving birth). In all cases the last dose (and only dose, in case of re-vaccination) is given at least two weeks before the expected date of farrowing.

Porcine circovirus type 2 (PCV2), is known to infect, and cause a wide variety of clinical signs and syndromes in pigs, some of which may be caused by PCV2 in combination with other agents. In piglets, PCV2 associated infections may include symptoms such as weight loss (or failure to grow), enlarged lymph nodes, difficulties in breathing, and, less commonly, diarrhoea, pale skin and jaundice (yellowing of the skin).

Circovac contains inactivated PCV2. When the gilt or sow is injected, the pig’s immune system recognises the inactivated virus as ‘foreign’ and reacts to this by producing antibodies to destroy it. These antibodies are transferred from the mother to the piglets through the colostrum, and they help the piglets to fight the PCV2 virus if they become exposed to it after they are born.

Circovac has been studied in several trials in pregnant pigs of various breeds. Both sows and gilts (and their piglets) were investigated in these studies, some of which were carried out under laboratory conditions and some on farms. The effectiveness of the product was demonstrated by measuring the amount of antibodies to PCV2 in the blood of the vaccinated sows (or gilts) and also in the blood of their piglets (after they have had the colostrum). The effectiveness of the product was further investigated in piglets which were directly exposed to the virus, by observing them for the development of circovirus-related symptoms. Parameters such as body weight, and the amounts of PCV2 found in some specific lymph nodes and in their blood and faeces, were taken into account.

Additionally, the overall number of deaths occurring in field conditions amongst piglets born to vaccinated sows and gilts was investigated and compared to those born to unvaccinated mothers. The length of time that Circovac is effective in the piglets has also been studied. The main measure of the immune response was the level of antibodies against PCV2 in the piglets’ blood.

The trials showed that vaccination of the mothers with Circovac can reduce the incidence of lesions associated with circovirus infection in the lymphoid tissues of their piglets. Although the outcome of some of the trials was partially compromised by the complex nature of PCV2 infections, the large number of pigs involved (from 63 farms) and the variety of experimental and clinical conditions did show a reduction in the overall death rates of piglets related to circovirus infections of between 3.6% and 10%.

Immunity in piglets born from vaccinated gilts or sows was shown to last for up to five weeks after they drank the colostrum.

Circovac can cause a harmless temporary redness or swelling at or around the injection site, which can last for up to four days after the injection. Following injection, pigs may have an increased body temperature of 1.4°C for up to two days, and in some pigs of up to 2.5°C, but this should not last more than 24 hours after the injection. Other rarer side effects in the injected pigs are reduced activity and food intake, but these are also temporary. For a full list of all side effects reported with Circovac, see the Package Leaflet.

Circovac contains mineral oil. Accidental injection may cause severe pain and swelling, particularly if injected into a joint or finger, which can in rare cases lead to the loss of the finger. If someone is accidentally injected with even a very small amount of this product, they must seek medical advice immediately and the Package Leaflet should be shown to the doctor. If pain persists for more than 12 hours after medical examination, the doctor should be contacted again.

Zero days.

The Committee for Medicinal Products for Veterinary Use (CVMP) agreed that the benefits of Circovac outweigh its risks for the reduction of the lesions in lymphoid tissues which are associated with circovirus infection in piglets and also to help reduce deaths connected with this disease in piglets. They recommended that Circovac should be given a marketing authorisation. The benefit-risk balance may be found in module 6 of this EPAR.

The European Commission granted a marketing authorisation valid throughout the European Union for Circovac to Merial on 21 June 2007. Information on the prescription status of this product may be found on the outer package.