The best time for people to get a shot to protect themselves from a vaccine-preventable disease is at the age of six, according to a new study.
The study, conducted by researchers at the University of Texas Medical Branch at Galveston, found that the average age at which people get vaccinated was between seven and 11 years old, but that this changed with the age at first starting to increase from 10 to 12.
A similar age-related decrease in vaccine-immunity rates occurred in the years after the 2009 pandemic.
However, the researchers say they are unsure why this occurred.
“It may be that in the United States, vaccination has become so widespread that older individuals are able to take the vaccine and thus the vaccine is effective at older ages, but it is unclear why older people are less likely to have been vaccinated,” the researchers wrote in the journal Vaccine.
They also questioned why a higher percentage of children, particularly those in school, are vaccinated.
While the researchers did not investigate the reasons why older adults are more likely to get the vaccine, they said it was likely because older people tend to have higher levels of immunisation.
For the study, they asked parents about whether they had had the vaccine when they were children.
Among those who had received the vaccine as an infant, about three-quarters of parents reported they had been vaccinated, compared with roughly half of parents who had not received the vaccination.
About half of the vaccine recipients had received their vaccine in childhood.
The study found that vaccination rates decreased with the year at which they were born, but this could be because older parents tend to get older as they get older.
Parents who had been immunised as infants also tended to report a lower rate of getting vaccinated, the study found.
More research is needed to determine the reasons behind this trend, the authors said.