**11. Treatment of HBV infection**

*Tourism*

infected with the viral agent) should be vaccinated with HBIG (0.04–0.07 ml/kg) as soon as possible after exposure. Immunization for the newborn babies should start immediately with the initial shot given at a site that is not similar with that for HBIG; an accelerated four dose immunization schedule (0, 1, 2, and 12 months) is required in the maternal-fetal transmission scenario [8, 77]. HBV can also be prevented by avoiding contact with contaminated blood and blood products and unprotected sexual exposure. Using condoms has also been shown to reduce the

Several reasons why people did not opt for pre-travel vaccinations include traveler's pre-knowledge regarding the prevention of diseases during overseas travel, the limited number of healthcare settings that gives immunization, and that some countries have not yet approved the number of vaccines a traveler needs [9, 31]. There are commercially hepatitis B vaccines available currently, for example, recombinant HBV vaccine (Engerix-B®, GlaxoSmithKline, and Recombivax HB®, Merck & Co., Inc.) and the HAV and HBV combined vaccine (Twinrix®, GlaxoSmithKline) [78]. The complete HBV vaccination requires three shots of vaccine. The normal timeline of the three intramuscular injections is to have the second and third injections given 1 and 6 months after the first dose. An accelerated schedule (doses on days 0, 7, and 21 and then a post-travel dose at 12 months) might be required if there is an inadequate time for immunization prior to travel [79, 80]. An HBV vaccine can also be used to treat persons who have been exposed to the

The prevalence of HBV differs between countries and regions, and therefore the number of persons acquiring protective immunity from a previous HBV infection also changes. Therefore, the recommendation of its vaccination should be hinged on likelihood of infection during travel and evidence of previous immunization or recovery from previous infection [74]. In those travelers without evidence of previous HBV immunity, HBV vaccination is recommended in those with HBV exposure risks and traveling to HBV endemic regions [78]. The CDC has recommend HBV vaccination to all persons without evidence of immunization before traveling to areas with intermediate and high prevalence of chronic hepatitis B and, irrespective of the traveler's destination, and based on the traveler's potential risky activities and exposures [11, 81]. High-risk activities might include unprotected sex with a new partner, getting a tattoo or piercing, or having any medical procedures like surgery [11, 81]. Studies have reported that only 19% of all American travelers and 30% of American travelers planning high-risk activities had received a completed HBV vaccination before departure irrespective of the recommendation made by the CDC [79]. This finding is in consonance with information from Europe that only 15% of international travelers to HBV endemic regions receive a completed HBV vaccination before travel [79]. There is often a very low immunity of HBV to travelers from low endemic regions and those born before the EPI schedules [82, 83]. Obviously, there are no recommendations for HBV serologic examination of international travelers currently. This might be because of the large population of international travelers, thus making it impossible to screen all for the virus. Reports have it that only 3.4–3.9% of the population in low endemic countries will have evidence of the HBV serologic markers prior infection [82, 83]. Vaccination of those populations should be considered when long-term travel is arranged to countries where HBV prevalence is intermediate or

chance of sexually transmitted infections [8].

**10. Immunization program for travelers**

virus, in order to prevent disease development [31].

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hyperendemic [31].

There are several antiviral treatments available for chronic HBV infection, and everyone with chronic HBV should be linked to care, considered for treatment, and checked for liver damage and liver cancer regularly [84]. Therapy of HBV reduces the amount of virus in the system and lowers the chance of developing to serious liver disease and liver cancer. However, most people cannot be cured of the viral agent, and as such therapy is recommended to continue for life [85, 86].

Worthy of note is the fact that there are currently two main antiviral drugs for the treatment of chronic HBV infection [87]. They are nucleos(t)ide analogues (NA) and interferon (IFN) including normal IFNs and pegylated IFNs (Peg-IFNs). NA gives a direct antiviral effect by stopping DNA polymerase. It is usually given orally. There are six types of NAs as approved for treatment of HBV by the WHO: Lamivudine (LAM), Adefovir (ADV), Telbivudine (TBV), Entecavir (ETV), Tenofovir disoproxil fumarate (TDF), and Tenofovir alafenamide (TAF). IFNs, especially the Peg-IFNs, have a suppressed antiviral effect than the NA therapy, but its persistent effect can be achieved with a finite therapy. It is usually given via subcutaneous injection. There are reports of combination therapy of NA + NA and Peg-IFN + NA [86, 87].

There are serious ongoing clinical trials for the development of more effective treatments and a cure for HBV infection [3, 6].
