Test for the serological diagnosis of antibodies against hemagglutinin-containing viruses. Principle: The incubation of hemagglutinating viruses (e.g. rubella) with antibody-containing patient serum leads to the inhibition of virus-induced hemolysis of indicator erythrocytes.
The HHT titer (also HAHT titer) is the value (reciprocal value) of the highest serum dilution at which haemagglutination is still prevented.