HIV transmission by blood transfusions in Stockholm 1979-1985: nearly uniform transmission from infected donors.

Thirty-five out of approximately 800 known HIV-seropositive people in Stockholm by mid-1986 were blood donors during the period 1979-1986. Almost all, i.e. 349 recipients of their blood components (red blood cells, platelets, plasma) could be traced. One hundred and eighty were still alive and 112 of these on further analysis, were suspected of being infected. They were contacted and all but one agreed to be tested for HIV antibodies. Fifty recipients were found to be seropositive. They had been transfused with blood components from 14 of the 35 donors. The earliest observed transmission occurred in June 1982. The patterns of HIV transmission showed, with only one exception, that each donor who had transmitted HIV to one recipient had also transmitted it to all later recipients. Appropriate preserved sera and clinical records from five of the donors who had not transmitted the virus were found and analysed. The result indicated that these donors had acquired their HIV infection after their last blood donation. In conclusion, our study indicates that every antibody-positive donor transmits HIV to almost every recipient.