Sick children appear to be "substantially" more likely to be prescribed antibiotics if they receive care via telemedicine than if they see a doctor in person, a new study indicates.

Researchers evaluated data for more than 500,000 insured children who saw a doctor for an acute respiratory infection – symptoms of which can include a runny nose, cough or sore throat – in 2015 and 2016. Children were prescribed antibiotics during 52% of direct-to-consumer telemedicine visits, compared with 42% of urgent care visits and 31% of primary care provider visits, according to the study, published Monday in the journal Pediatrics.

Antibiotics prescribed during telemedicine visits also were less likely to meet clinical guidelines, the study found, raising questions about the quality of care delivered through the virtual assessments. An unnecessary antibiotic prescription can be tied to side effects and antibiotic resistance.

"We know very little about the care children receive during these direct-to-consumer telemedicine visits, which occur with doctors outside of the child's usual pediatric office," Dr. Kristin Ray, a pediatrician at UPMC Children's Hospital of Pittsburgh and the study's lead author, said in a statement.

Access to telemedicine has expanded in recent years, and has been touted as a promising way to address doctor shortages and other barriers to care. Previous research published by authors of the new study indicates the use of telemedicine among children soared from 2011 to 2016, particularly for treatment of acute respiratory infections.

In so-called direct-to-consumer telehealth, patients generally seek care for common complaints through phone or video conferencing. The direct-to-consumer sector is made up primarily of for-profit, private companies .

While expanding telemedicine can help make health care more accessible to families, "I think it also is important to make sure the quality of the care that children receive remains high," Ray said.

Children who were older, enrolled in high-deductible health plans and living in the South were more likely to be seen through telemedicine visits, the study found. About 5 percent of telemedicine visits were for children younger than 2.

The American Academy of Pediatrics has recommended that children younger than 2 should not receive acute care services via telemedicine if the provider is not a pediatrician and not directly linked to the child's regular medical home.