Eradication of hepatitis B

Eradication of hepatitis B

FACTS
WHO estimates that in 2015, 257 million people were living with chronic hepatitis B virus (HBV) infection worldwide, and that 900 000 had died from HBV infection, mostly as a result of cirrhosis or hepatocellular carcinoma. Most HBV-associated deaths among adults are secondary to infections acquired at birth or in the first five years of life. In May 2016, the World Health Assembly endorsed the Global health sector strategy on viral hepatitis, which calls for the elimination of viral hepatitis as a public health threat by 2030 (defined as a 90% reduction in incidence of new infections and a 65% reduction in mortality). Elimination of HBV infection as a public health threat requires a reduction in the prevalence of hepatitis B surface antigen (HBsAg) to below 0.1% in children 5 years of age. This can be achieved through universal immunization of newborns against hepatitis B and other interventions to prevent mother-to-child transmission of HBV.

HOW IS HBV DIAGNOSED
It is not possible, on clinical grounds, to differentiate hepatitis B from hepatitis caused by other viruses. Laboratory confirmation of the diagnosis is therefore needed.
Chronic infection is diagnosed by a positive test for the surface antigen of HBV (HBsAg). When a person tests positive for HBsAg, an HBV DNA test should also be done to determine how high the viral load is. Those with a high HBV viral load and with raised liver enzymes may need to be put on long-term antiviral treatment for their own health. Persons with cirrhosis are also in need of treatment. However, only a proportion of people with chronic HBV infection will require treatment. If the HBV DNA test is not available, a test for e-antigen of HBV (HBeAg) is sometimes used to give a less accurate indication of the level of virus in the blood.
Hepatitis B is spread mainly through exposure to various body fluids, including blood, saliva, menstrual, vaginal, and seminal fluids. Worldwide, the virus is most commonly spread from mother-to-child during birth (vertical transmission) as well as through horizontal early childhood transmission, and these routes of HBV transmission are responsible for most chronic infections. Transmission can also result from unsafe injections and poor infection control practices during medical, surgical, and dental procedures, sexual transmission among men who have sex with men, and through unscreened blood donations.

HOW IMPORTANT IS MOTHER-TO-CHILD TRANSMISSION OF HEPATITIS B?
Worldwide, the most common route of transmission of hepatitis B is mother-to-child during birth (vertical transmission) as well as through horizontal early childhood transmission. These routes of HBV transmission are also responsible for most chronic infections. Therefore, prevention of these infections from mother-to-child or early childhood transmission is the most important strategy to control the HBV epidemic. Transmission of HBV from mother to child is more common in children born to women who have a high level of hepatitis B virus in the blood (known as HBV viral load).
In the absence of any preventive interventions, the risk of transmission from mother to child ranges from 70% to 90% for mothers with high HBV viral load (or are HBeAg-positive) and from 10% to 40% for those that are HBeAg negative. These high maternal concentrations of HBV DNA (viral load) are associated with an elevated risk of transmission, even among infants who receive the hepatitis B vaccine. For this reason, pregnant women with high HBV DNA levels may benefit from antiviral prophylaxis during pregnancy to prevent mother-to-child transmission and protect their infants from becoming infected.

CAN HBV INFECTIONS BE PREVENTED?
Yes, there is a safe and effective vaccine. Three doses provide 98%-100% protection against HBV infection. WHO recommends that all infants receive a first dose of the hepatitis B vaccine as soon as possible after birth, preferably within 24 hours. This birth dose should be followed by at least 2 additional doses, given at least 4 weeks apart. Protection lasts at least 20 years and is probably lifelong. Since 1992, WHO has recommended the inclusion of the hepatitis B vaccine as part of routine vaccination services through the Expanded Programme on Immunization. Infant hepatitis B immune globulin (HBIG) prophylaxis (preventive treatment) shortly after birth and preventive maternal peripartum prophylaxis (preventive treatment) antivirals can provide additional protection to that provided by a timely birth dose of hepatitis B vaccine.

HOW FEASIBLE WILL IT BE TO IMPLEMENT THESE NEW RECOMMENDATIONS
Experience from elimination of mother-to-child transmission of HIV and syphilis suggests that providing testing for pregnant women followed by antiviral prophylaxis for eligible women to prevent infection is feasible. Programmes aimed at preventing mother-to-child transmission of HIV are the most mature and have shown remarkable success. For example, by the end of 2018, approximately 79% of pregnant women globally knew their HIV status, and 82% of those who tested positive for HIV received treatment. However, although the majority of women are offered HIV testing at antenatal care visits, the same is not yet true for syphilis or HBV testing.
An online consultation held in 2019 as part of the guidelines development process among 153 health care workers, 56 programme managers and 81 civil society representatives reported that 77% of respondents felt it was feasible to provide HBV testing and offer eligible pregnant women tenofovir prophylaxis. Challenges reported by stakeholders included the high cost and low availability of HBV viral load assessment, inadequate training of health care workers, limited knowledge of HBV infection among women living with HBV infection, and a lack of capacity and infrastructure to test and treat pregnant women. These issues will need to be addressed to enable full implementation of routine testing of all pregnant women, as well as the use of antivirals in those with high HBV viral load or HBeAg status.

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