Secular trends of chickenpox among military population in Israel in relation to introduction of varicella zoster vaccine 1979–2010

Abstract

Chickenpox is a contagious disease caused by the varicella zoster virus. There is scarce data on long-term trends of chickenpox and its relation to vaccinations practices. We aimed to evaluate trends of chickenpox in a military population during the period 1979-2010 and to assess temporal associations in relation with the introduction of varicella zoster vaccine to the civilian population in Israel in 2000. The archives of the Epidemiology Section of the Israel Defense Forces, where chickenpox is a notifiable disease, were reviewed for all cases of chickenpox from January 1, 1979-December 31, 2010. Annual and monthly incidence rates were calculated and analyzed in relation to vaccine introduction. Between 1979-2000, incidence rates fluctuated around 10 cases per 10,000 soldiers without a clear trend. Since 2000 there has been a dramatic 10-fold decline in incidence, especially notable since 2008, from eight per 10,000 soldiers in 2000 to the lowest rate ever recorded, in 2009, of 0.57 cases per 10,000 soldiers. A seasonal sinusoidal pattern was clearly demonstrated, with rising incidence from November to May followed by a gradual decline to October. The results of this long-term study suggest that the rates of chickenpox in the military population have significantly declined since the introduction of the vaccine to the civilian population in Israel and almost disappeared completely since 2008 as the vaccine was included in the state-funded routine childhood immunization schedule. These findings underscore the need for a strong surveillance system and will aid in determing vaccination policies.

Seroprevalence of measles, mumps and rubella among young adults, after 20 years of universal 2-dose MMR vaccination in Israel

“…Such study might include varicella seroprevalence in light of the changing epidemiology of chickenpox with introduction of MMRV vaccine. 20 Boosting studies can aid in understanding immune responses and sero-epidemiology. Those studies should be carried in the appropriate context, taken their interventional nature.…”

An economic analysis of varicella immunization in the Singapore military

“…An Israeli study of secular trends of chickenpox among the military population in Israel in relation to the introduction of varicella zoster vaccine 1979–2010 suggests that the rates of chickenpox in the military population have significantly declined since the introduction of the vaccine into the civilian population in Israel and have almost disappeared completely since 2008, when the vaccine was included in the state-funded routine childhood immunization schedule; however, this study did not include an economic evaluation of the vaccination program [ 6 ]. The authors further concluded that these findings underscore the need for a strong surveillance system and will aid in determining vaccination policies.…”

“…In addition, because the infectious period begins when respiratory symptoms occur [ 2 ], the public health management of outbreaks is difficult in densely populated military camps. However, studies conducted in the United States [ 3 – 5 ] and Israel [ 6 ] have shown that the vaccination of newly recruited military servicemen susceptible to varicella was a cost-effective measure that reduces the incidence of chickenpox and hospitalization. So far, there have been no similar studies conducted for militaries based in the tropics, and this paper serves to fill this gap in the literature.…”