A single injection at birth can protect children from HIV for years.

Administering a single gene therapy injection at birth appears to protect against HIV, the virus that causes AIDS, for years. The therapy takes advantage of a critical window in the first years of life, something that, according to a study published in the journal Nature , could redefine the fight against pediatric infections in high-risk regions.

This study is one of the first to demonstrate that the first few weeks of life, when the immune system is naturally more tolerant, may be the optimal time to administer gene therapies that would otherwise be rejected at older ages.

More than 100,000 children contract HIV annually , primarily through mother-to-child transmission after birth through breastfeeding. “Nearly 300 children become newly infected with HIV every day,” says first author Amir Ardeshir of the National Primate Research Center in California , USA. Antiretroviral treatments have been shown to be effective in suppressing the virus and limiting transmission; however, treatment adherence and access to doctors decline after birth, especially in areas with limited access to medical care. “ This approach could help protect newborns in high-risk areas during the most vulnerable period of their lives ,” he says.

In the study, nonhuman primates received a gene therapy that reprograms cells to continuously produce antibodies that fight HIV. Timing was crucial for the single treatment to offer long-term protection.

Animals that received treatment during their first month of life were protected from infection for at least three years without the need for a booster dose, which in humans could mean coverage until adolescence . However, those that received treatment between 8 and 12 weeks showed a more developed and less tolerant immune system, which did not accept the treatment as effectively.

"This is a unique treatment tailored to the critical time when these HIV-positive mothers in resource-limited areas are most likely to seek medical advice," Ardeshir says. "As long as the treatment is administered close to birth, the baby's immune system will accept it and consider it part of itself."

Researchers used an adeno-associated virus (AAV) to introduce genetic code into muscle cells that enables them to produce broadly neutralizing antibodies (bNAbs) against various HIV strains. This method avoids the need for repeated antibody infusions, which are costly and difficult to implement in low-resource settings. Muscle cells act as antibody "microfactories," offering long-lasting protection .

In newborns, the treatment generated high tolerance and effective levels of bNAb, preventing HIV infection in simulated breastfeeding and sexual transmission. Furthermore, prenatal exposure to antibodies facilitated acceptance of gene therapy at later ages, reducing the risk of immune rejection.

Ardeshir believes that a single injection at birth offered a more cost-effective and feasible solution in the real world, while placing less burden on the mother during a follow-up visit.

Regarding its application in humans, experts acknowledge that some questions remain to be resolved.

However, if successful, this treatment could dramatically reduce rates of mother-to-child HIV transmission in high-risk regions like sub-Saharan Africa , where 90% of pediatric HIV cases are concentrated. It could also be adapted to protect against other infectious diseases such as malaria, which disproportionately affects young children in low-income countries.