Poliomyelitis in the Netherlands before and after vaccination with inactivated poliovaccine

Abstract

Formalin-inactivated polio vaccine has been used in the Netherlands since 1957. Within 3 years all children born in 1945 and later were offered vaccine. In the first years poliovaccine from different manufacturers were used. In 1961 a vaccine produced in the Netherlands by the ‘Rijks Instituut voor de Volksgezondheid’ (National Institute of Public Health) became available and in 1962 the poliomyelitis components were incorporated in a quadruple vaccine, which contains 15 Lf diphtheria, 5 Lf tetanus toxoid and 16 × 109Bordetella pertussis organisms in addition to the three polio components. As an adjuvant this quadruple vaccine contains 1·5 mg. aluminium phosphate per 1 ml. dose. For infants the schedule became three doses at ages 3, 4 and 5 months respectively, followed by a booster dose at the end of the first year. The over-all acceptance rate can be estimated at almost 90% of those eligible, but there were pockets in the population with lower rates.Since 1924 poliomyelitis has been a notifiable disease. During and after the last World War major epidemics occurred.The poliomyelitis morbidity rates in the 8 post-vaccination years 1958–65 were compared with those from two preceding 4-year periods 1950–3 and 1954–7. In the 1–4-year-old children, who presented the most vulnerable age group, paralytic poliomyelitis was reduced by about 97 % and in the other age groups this percentage was slightly less. The over-all reduction was 96 %. Comparison of the morbidity rates of non-vaccinated persons in 1958–65 with the rates from 1950–3 and 1954–7 gave an impression of the extent of the herd immunity. These rates were reduced 70–80 % in the children under 15 years and 90–95 % in those over this age. The individual protection given to the vaccinated was calculated from the morbidity rates in non-vaccinated, incompletely and fully vaccinated persons in the 1958–65 period. The reduction of morbidity was 90–95% for children of 1–14 years who got three doses or more and about 85 % for those who had only 1 or 2 doses. Fully vaccinated children, who are profiting from both individual protection and herd immunity, showed a reduction of 97–99 %.From the data presented it is concluded that vaccination with inactivated poliomyelitis vaccine can provide very effective protection for the individual and the community provided that a vaccine of good quality is used and the rate of acceptance is 75 % or better.