Duration of short-lived cross-protective immunity against a clinical attack of dengue: A preliminary estimate

Abstract

It is believed that primary infection with a single serotype of dengue virus elicits short-lived cross-protective immunity against other heterologous serotypes; however, the duration of cross-protection has not been explicitly estimated using epidemiological data. To offer an empirical estimate of the duration, the present study re-analysed historical cohort data of multiple clinical attacks of dengue among American soldiers in the Philippines from 1922-24. In the original study, the historical cohort of 299 cases with a first clinical attack of dengue were closely surveyed; 99 (33.1%) experienced a second attack, while the remaining 200 returned to the United States without further attacks. The time intervals from first to second attack among the 99 cases, and from first attack to departure to the United States among the 200 soldiers, were used for estimating the duration of cross-protective immunity based on a simple mathematical model. Employing an exponential distribution or Kronecker's delta function as the loss function of cross-protection against a second clinical attack, the mean duration of cross-protective immunity since the first clinical attack was estimated as 6.90 (4.87, 11.83) days and 7.52 (4.88, 16.38) days, respectively. The force of infection, which was jointly estimated with the duration of cross-protection, reasonably explained the other observed epidemiological information in the data, supporting the finding of a short cross-protection period. Even though the estimates suggested that the first clinical attack most likely elicited cross-protective immunity, the length of cross-protection lasted only 1-2 weeks, far shorter than previously believed.