The new study revealed 93% of doctors receive requests from parents to spread out vaccinations for their children.
The research team - including Dr. Alison Kempe, professor of pediatrics and director of the Adult and Child Center for Health Outcomes Research and Delivery Science (ACCORDS) at the University of Colorado School of Medicine and Children's Hospital Colorado - publishes its findings in the journal Pediatrics.
There are 14 vaccinations that the Centers for Disease Control and Prevention (CDC) say children should receive between birth and the age of 6 years. It is recommended that parents get their children vaccinated in line with the suggested immunization schedule, which states certain vaccines need to be administered at specific ages in order to boost their effectiveness.
For example, it is recommended that the MMR (measles, mumps and rubella) vaccine be given to children in two doses, with the first dose being administered between the ages of 12-15 months and the second dose being given at 4-6 years.
But in this latest study, Dr. Kempe and colleagues find more and more parents are asking health care providers to delay vaccines for young children, putting their own and other children at risk of preventable diseases.
To reach their findings, the researchers sent surveys via e-mail and mail to a nationally representative sample of 815 pediatricians and family doctors between June and October 2012.
The surveys asked these health care providers how often they had received parental requests to spread out immunization schedules for children under the age of 2 years, how they responded to these requests and the reasons behind their responses.
93% of doctors have received parental requests to alter vaccination schedules
Of the 534 (66%) pediatricians and family doctors who responded to the survey, 93% said they had received requests from parents to spread out vaccinations for their children, with 21% of respondents revealing they had received such requests from more than 10% of parents.
Concerns about short- and long-term complications, concerns that vaccines may increase the risk of their child developing autism, and the belief that their child is unlikely to contract a vaccine-preventable disease were some of the reasons cited for parents requesting to delay vaccinations, according to the respondents.
Despite 87% of respondents saying they believed such requests were putting children at risk of preventable diseases and 84% saying they believed bringing children back for separate injections caused them more pain, the majority of health care providers "often/always" or "sometimes" agreed to alter vaccination schedules, according to the researchers.
Around 82% of respondents said they believed agreeing to parental requests to spread out vaccination schedules would help them build trust with families, while 80% believed families might leave their practices if they refused such requests.
While the majority of family doctors and pediatricians reported using a variety of strategies to encourage patients to adhere to recommended vaccination schedules for their children, most believed they were ineffective.
Dr. Kempe and colleagues say their findings raise some concerns, noting that delaying or spreading out childhood vaccines increases rates of under-vaccination. This puts children and other vulnerable populations - such as the elderly - at increased risk of contracting diseases that are highly preventable.
The researchers add:
"Virtually all providers encounter requests to spread out vaccines in a typical month and, despite concerns, most are agreeing to do so. Providers are using many strategies in response but think few are effective. Evidence-based interventions to increase timely immunization are needed to guide primary care and public health practice."
The team says interventions that educate parents about the safety and effectiveness of vaccines need to begin in early pregnancy, and they encourage increased utilization of social networks and public messaging in helping parents to make informed decisions about vaccinating their children.
In a Spotlight feature last month, Medical News Today investigated whether ongoing concerns about vaccine safety have contributed to the current measles epidemic in the US.