HIV and hepatitis B virus (HBV) are transmitted in similar ways, and coinfection with both viruses is common. People who are living with HIV are more likely to develop chronic hepatitis B and have more complications and a higher mortality rate than those with HBV alone. While guidelines recommend that people living with HIV should be vaccinated against HBV, some do not respond well due to weakened immune function. But new research suggests that upping the dose could help. Researchers compared three shots using a double dose of the Engerix-B HBV vaccine versus a repeated series of three standard doses in 107 HIV-positive adults who didn’t produce enough antibodies after initial vaccination. The high-dose group produced more antibodies than the standard-dose group: 72% had a good serological response, compared with just 51% of those who repeated the standard series. What’s more, after one to two months of follow-up, antibody levels were more than twice as high in the high-dose group.