DRUG addicted prisoners have shown themselves willing to have tetanus shots, as the outbreak of the disease claimed its 12th victim. Another drug addict suffering from tetanus was admitted to the United Christian Hospital on Sunday, bringing the number of cases to 28. The territory's 23 methadone clinics began offering tetanus shots yesterday after the New Year break. Although drugs workers warned that acceptance of the vaccinations were likely to be slow, the Correctional Services Department (CSD) reported that the majority of drug addicted offenders had agreed to be immunised. A spokesman for the CSD said: ''The response in prisons and the Drug Addiction Treatment Centre has been very encouraging so far with the vast majority agreeing to tetanus immunisation. ''We are trying to locate all injecting drug users within the 20 CSD institutions and then attempting to persuade them to have the tetanus shots.'' Prison doctors are also looking out for inmates suffering from muscular spasms - a symptom of tetanus - but so far no cases of the disease have been discovered in the territory's jails. Although the latest number of drug addicts immunised at methadone clinics was not available, the number of vaccinations at three clinics which started offering the shots more than two weeks ago has been small. Last week the Health Department estimated that the three clinics had immunised 660 addicts - only a few more than the number of patients who visit the Wan Chai methadone clinic in just one day. There are estimated to be about 20,000 intravenous drug addicts in Hong Kong but it is not known how many of these are in prisons or other CSD institutions. Officers from the Narcotics Bureau are continuing to test heroin samples but have not yet found any evidence of the contamination which is thought to have caused the tetanus outbreak. The Government Information Services are working on a poster and leaflet warning drug addicts about tetanus and urging them to be vaccinated.