On 25 April, Meera Chand, director of clinical and emerging infections at UK Health Security Agency stated that "Information gathered through our investigations increasingly suggests that this rise in sudden onset hepatitis in children is linked to adenovirus infection".[1][18] It was reported in the BBC News which also stated that some scientists felt that the increase in cases could be caused by a change in the genetic make-up of adenovirus, which can cause hepatitis, so that it causes liver inflammation more readily.[18] Another explanation is that restrictions imposed during the COVID-19 pandemic led to young children to be exposed to adenovirus at a later point in their lives leading to a stronger immune response.[18] Other explanations include toxins and viral co-infection with COVID-19.[19] According to the WHO, these theories require further investigation.[4]