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  Epidemiology of hepatitis B infection in Finland: Implications for immunisation policy

Monday, 9th of January 2017

o    Epidemiology of hepatitis B infection in Finland: Implications for immunisation policy

Vaccine, Pages 412-418

Tanja Karvonen, Kari Auranen, Markku Kuusi, Tuija Leino

Abstract below; full text is at http://ac.els-cdn.com/S0264410X1631180X/1-s2.0-S0264410X1631180X-main.pdf?_tid=60acb5fa-d66a-11e6-8403-00000aab0f6b&acdnat=1483966485_2dac7d48e675d443aea46bc515543dbf

 

    Objectives

We describe the current epidemiology of acute and chronic hepatitis B infections in Finland. We estimate the total incidence of chronic hepatitis B following from the current incidence of acute infections and the influx of chronic carriers of hepatitis B associated with net immigration. We evaluate the incidence of hepatitis B infections preventable by a universal vaccination programme among infants.

Methods

We analysed hepatitis B cases reported to the National Infectious Disease Register during 2004–2012 and used pre-developed methods to adjust for acute asymptomatic infections. We estimated the projected incidence of chronic infection by applying age-specific risks of chronic infection to the estimated incidence of acute infection. We estimated the influx of chronic carriers associated with immigration by utilising data on immigration during 2004–2012 and the WHO regional estimates of carriage prevalence.

Results

The estimated incidence of acute hepatitis B infection in Finland, adjusted for asymptomatic infections, was 1.67 per 100,000 per year (95% Crl 1.43–1.94) which is 4.2-fold to the register-based incidence. The estimated lifetime risks of acute and chronic hepatitis B infections were 0.13% and 0.01%, respectively. We estimated that annually seven new chronic infections would result from infections acquired in Finland. These new chronic infections accounted for 1.2% of the total incidence of chronic infections. We estimated that eventually three chronic infections per year would be potentially preventable by a universal infant vaccination programme.

Conclusions

Partly due to the fact that hepatitis B infections in neonates and in children are rare, a very limited number of chronic hepatitis B infections resulted from infection acquired within the country. A vast majority of chronic hepatitis B infections occurred among foreign-born persons and were therefore not preventable by a universal infant immunisation programme in Finland. Even with a targeted immunisation programme, the incidence of hepatitis B infection has remained low.