Over the years many concerns have been raised about chilhood vacinations, and one concern has been that multiple vaccinations 'use up' the immune system, so children are unable to fight off other illnesses.
A study by Danish researchers has concluded, after monitoring over 805,000 children, that receiving multiple vaccinations does not increase a child's risk of being hospitalised due to infectious diseases.
They found no link between jabs, including MMR and Hib, with an increased risk.
Meanwhile vaccine campaigners are calling for more research.
A research team from the Statens Serum Institut in Copenhagen, linked to the Danish Ministry of the Interior and Health, which studies vaccines, monitored all children born in Denmark between 1990 and 2001.
They looked at routine childhood vaccines, including Hib (Haemophilus influenza type B), DTP (diphtheria-tetanus-inactivated poliovirus), MMR (measles, mumps and rubella) and the polio vaccine.
They also looked at how many children were admitted to hospital for acute upper respiratory tract infections, viral or bacterial pneumonia, viral central nervous system infections, bacterial meningitis or diarrhoea in the five years after the dates of their vaccinations.
As people living in Denmark are given a unique ID number in the country's civil registration system, the researchers were able to track each child.
They say they found the only adverse association was for Hib and acute upper respiratory tract infection, but insist this was within the limits of what would be expected by chance alone, and not time or vaccine dose related.
They found no link between the total number of vaccines received in multiple jabs (up to 13) and infection risk.
The team led by Anders Hviid said they found 15 associations where vaccination appeared to protect against conditions other than those it was targeted at, and add that their results 'do not support the hypothesis of increased risk of infectious disease hospitalisation after childhood vaccination'.
Dr Mary Ramsay, consultant epidemiologist at the Health Protection Agency, says young infants are exposed to large numbers of antigens in everyday experience and the immune system has the capacity to respond to thousands.
She says most experts were not concerned that there was any risk of immunological overload from childhood vaccines, but public anxiety, and concern by a small group of health professionals needed more reassurance that vaccination was safe.
She says that this study suggests that vaccination might reduce the risk of other infectious conditions, and is consistent with similar studies looking at hospital admission after MMR vaccine.
But Jackie Fletcher of Jabs, which believes 1,000 children in Britain have been damaged by the MMR jab, maintains there is a susceptible group of children who have vulnerable immune systems, and could be identified before vaccinations were given.
The report is published in the JAMA: The Journal of the American Medical Association.