APASL 2020| Prof. Rosmawati Mohamed: Dialogue HBV mother-to-child transmission of hot issues, so that hepatitis B mother rest assured pregnancy

Chronic hepatitis B virus (HBV) infection is an important cause of chronic liver disease and the main reason for the high incidence of liver cirrhosis and liver cancer in China.At the 29th Annual meeting of the Asian Pacific Association for the Study of the Liver (APASL2020), Professor Rosmawati Mohamed from The University of Malaya Shared the latest development of chronic HBV infection in pregnancy and accepted an interview with Hepatology Digest on some hot issues.The report is as follows.

<Hepatology Digest>: You talked about hepatitis B in pregnancy. Can you give us an overview of the subject?

 

Dr Mohamed: The main focus is ensuring that mothers who are HBsAg-positive do not transmit the virus to their babies. The risk of having an infection at birth means there is a high chance of chronic infection or lifelong infection. 

 

To break the viral cycle, there must be an emphasis on the birth dose vaccination given within 12 hours of delivery, plus the first dose of the hepatitis B vaccination series, which includes three doses within six months. That can help prevent mother-to-child transmission of hepatitis B in 95% of cases. 

 

However, there are some studies that show that if mothers have a very high viremia, the chance of transmission is much greater. So to prevent transmission, another strategy is needed, whereby mothers with a high viral load are given antiviral therapy during pregnancy. This has been shown to further reduce transmission rates to as low as zero if treated early enough in the pregnancy. This is usually applied in the third trimester. 

 

Classically, we avoid giving drug therapy in the first trimester, mainly because that is the time of fetal development. If given solely for the purpose of preventing mother-to-child transmission, the drugs generally take around 3 months to work, unless the risk is heightened by the mother’s viral load being very high. So, we may need to start therapy as early as week 24 of the pregnancy, instead of the regular 30-32 weeks. 

 

Basically, we have been talking about the reduction of the virus at the time of delivery, because that is when transmission occurs to the infant. Therapy then stops at delivery. Some people may continue on afterwards, from 4-12 weeks after delivery, because of the risk of flares occurring. It is well known that stopping antiviral treatment can lead to viral flares post-delivery due to hormonal changes that occur. This risk can be as high as 25%. Generally, the flares that occur are mild unless there is advanced liver disease or cirrhosis that was not detected earlier, and in those cases therapy should be extended rather than stopped at time of delivery.

 

<Hepatology Digest>: Is there a risk of creating drug-resistant viral strains by giving antivirals, in the same way that antibiotics might?

 

Dr Mohamed: The risk of the drug crossing over to the newborn is quite low, which is why breastfeeding is not contraindicated if the mother is on antiviral therapy. In general, it is safe. We only allow certain categories of drugs to be given in association with pregnancy. We are balancing risk and benefit. In most circumstances, we use category B drugs because there are no animal studies that suggest there is any harm.

 

<Hepatology Digest>: What are the factors besides high viral load associated with a high risk of perinatal transmission of hepatitis B?

 

Dr Mohamed: Most studies have shown that the maternal viral load is the most important factor. But it must be stressed that the most important preventative strategy is still vaccination, and that relies on the timely optimization of the birth dose within 12 hours of delivery, the first dose vaccine, and then completing the course. It has to be stressed that that is the most important aspect, and the use of antiviral therapy during pregnancy is an add-on strategy.

 

<Hepatology Digest>: You mentioned stopping the antiviral therapy at a specific time, and also the possibility of flare. Could you elaborate on that a little more?

 

Dr Mohamed: In most cases, antiviral therapy would be stopped at the time of delivery, and that would be sufficient. There is a slight risk of flares occurring, but studies show that extending therapy to 12 weeks post-delivery does not make a huge difference in incidence. Flares can occur even if you aren’t taking antiviral therapy.

 

<Hepatology Digest>: You ended your talk outlining the triple elimination strategy. Can you describe that?

 

Dr Mohamed: Triple elimination is a framework that promotes a coordinated approach for eliminating mother-to-child transmission of not just hepatitis B, but also HIV and syphilis. Hepatitis B is the newest issue to be considered, and it can be coordinated with strategies for HIV, allowing for integration of services to prevent further hepatitis B transmission. 

 

I used the Western Pacific region, which includes China, as an example, where hepatitis B vaccination targets have been implemented early on. Consequently, success has been seen early with a reduction in HBsAg prevalence to <1% in children, which reflects tremendous benefits in reducing the number infected as well as mortality. There has been a reduction of seven million deaths in the Western Pacific alone since introducing hepatitis B vaccination programs. 

 

If we continue on in this way, the results will be excellent, but will not be good enough to achieve the 2030 target of 0.1% prevalence of hepatitis B amongst children. 

 

So what we want to do now is expand prevention, and we have introduced an incremental approach involving testing mothers for HBsAg, introducing hepatitis B immunoglobulin, as well as antiviral therapy for the mothers.