More than half of infants living with a household member infected with hepatitis B had a potential source of exposure other than their mother, according to new US research.
The findings have raised concerns about changes to American childhood vaccination recommendations that no longer routinely call for every newborn to receive a hepatitis B vaccine immediately after birth.
Researchers examined records involving approximately 158,000 children in Northern California and identified more than 2,000 who lived in households with at least one person carrying an active hepatitis B infection.
In approximately 58% of those cases, the infected household member was someone other than the child's mother.
"A child can be exposed to hepatitis B virus from anyone with an active infection, not just their mother," said Dr Karen Jacobson of Kaiser Permanente, who led the research.
The findings were presented at IDWeek, an annual infectious diseases conference held in Washington, according to Reuters reporting carried by Asharq Al-Awsat on 25 October.
The research comes after the US Centers for Disease Control and Prevention revised its recommendations for hepatitis B vaccination at birth.
Under the new guidance described in the report, newborns are recommended to receive the vaccine immediately if their mothers have hepatitis B or if their mothers' infection status is unknown.
For decades, the CDC had recommended a universal birth dose, meaning all medically eligible newborns received the vaccine regardless of their mothers' infection status.
The revised approach is part of wider changes to federal vaccination policy under US Health Secretary Robert F. Kennedy Jr.
Researchers say that focusing on maternal infection status alone may overlook other people who could expose an infant to the virus.
Hepatitis B is a viral infection that attacks the liver and can cause both short-term illness and lifelong disease.
The virus spreads through exposure to infected blood and certain other bodily fluids. It can also survive on contaminated surfaces for at least seven days, creating potential risks when infected blood is present.
Although many adults recover from acute hepatitis B infection, the consequences can be considerably more serious for infants and young children.
According to the World Health Organization, approximately 90% of infants infected during their first year of life develop chronic hepatitis B.
Chronic infection can persist for decades and increase the risk of cirrhosis, liver failure and liver cancer.
The age at which infection occurs is therefore an important factor in determining the likelihood of lifelong complications.
Hepatitis B vaccination has long been a central part of efforts to prevent transmission, particularly because an infected person may not know they carry the virus.
The birth dose provides early protection before infants may encounter infected household members or other potential sources of exposure.
Researchers highlight household exposure
The Northern California study examined household infection patterns rather than directly measuring how many infants contracted hepatitis B.
Its findings therefore identify possible routes of exposure but do not establish that any particular child became infected because of the revised vaccination recommendations.
The researchers' central concern is that screening mothers alone cannot identify every potential source of infection within a newborn's environment.
Relatives and other household members may carry the virus without showing symptoms, and their infection status may not be known to parents or healthcare professionals.
"No one knows the status of everyone who may come into contact with an infant," Jacobson said.
She argued that vaccination at birth offers protection against both recognised and unidentified sources of exposure.
The findings add to the debate over whether a vaccination strategy based primarily on maternal infection status can provide the same level of protection as universal newborn immunisation.
The study did not establish how many additional infections might occur under the new recommendations.
Its findings instead show that a substantial proportion of infants living with someone who has hepatitis B may encounter a potential source of infection outside the mother-child relationship.
