Jan 8 (Reuters) - Merck ( MRK ) on Thursday said any

changes to the U.S. child and adolescent immunization schedule

should rest on comprehensive data and guidance from vaccine

experts, after federal health officials shifted several shots

out of ‌the "universally recommended" category.

The Department of Health and Human Services and the ​Centers

for Disease Control and Prevention this week moved vaccines ‍for

rotavirus, influenza, meningococcal disease and hepatitis A ⁠to a

"shared clinical ⁠decision-making" category, telling parents to

consult healthcare providers.

Public health specialists warned the ‌rollback could drive

preventable hospitalizations and ​deaths by lowering uptake for

routine childhood immunizations.

"Clear, evidence-based recommendations remain essential to

support informed decisions and ⁠ensure that children and

adolescents receive ‍reliable ​protection against preventable

diseases," Merck ( MRK ) said, adding that declining vaccination rates

can have serious consequences amid recent U.S. outbreaks.

The ‍company said it "stands firmly behind an immunization

framework grounded in rigorous science, strong regulatory

processes and ongoing safety monitoring," and said it would work

with public health partners on policies that protect children

and adolescents.

President Donald Trump last month ​urged ‍the United

States to "align with other developed nations" by reducing the

number of shots for children.

Merck ( MRK ) said international comparisons ​require context,

including differences in disease burden, healthcare

infrastructure and population needs.

Bernstein analysts said Merck ( MRK ) could take the biggest hit

from the schedule changes, estimating a potential $2 billion

impact on annual revenue because of exposure to its rotavirus

vaccine RotaTeq and the human papillomavirus vaccine ​Gardasil.

The updated schedule also calls for a single dose of the HPV

vaccine for U.S. children, rather than the two-dose series

typically used for ‍most adolescents.