Haemagglutination inhibition antibody levels one year after natural measles infection and vaccination.

An assessment of haemagglutination inhibition antibody (HAI) titres of 1,163 children, comprising 739 recipients of live measles vaccines and 424 patients with natural measles infection after 1 year was made in this investigation. Statistical analysis revealed a significant difference in the levels of HAI antibodies. Of the vaccinated children a significant 67.45% showed antibody titres of less than or equal to 1:16, while only 23.48% of children with natural measles showed these antibody titres. The importance and implication of such HAI antibody titres is discussed.