WASHINGTON—Senior Republicans and Democrats expect the next round of coronavirus aid to include tens of billions of dollars to fund vaccine research and the broad distribution of an eventual vaccine, but they have disagreements over how much Americans should be charged for it.

Senate Majority Leader Mitch McConnell (R., Ky.), ahead of the start of expected aid negotiations next week when Congress returns to Washington, said he expects Congress to play a central role in vaccine logistics.

“Any way the federal government can be helpful in the distribution process…[it] certainly would be a logical thing for us to be involved in,” Mr. McConnell said Wednesday in Kentucky. Once a vaccine has been successfully developed, how do you get all the production you need, and how do you get it out? That is a role we obviously will be playing a part in.”

This week Senate Democrats released a proposal to include $25 billion to support vaccine research, purchase it for the U.S. population and make sure the country has the supplies and workforce needed to distribute it widely. They also called for an initial national plan from the Trump administration by early August.

“The decisions about how it is prioritized in terms of distribution should be driven by public-health experts, not by politicians,” said Sen. Patty Murray of Washington, the top Democrat on the Senate health committee. “A plan is absolutely essential.”

Sen. Roy Blunt (R., Mo.), who leads the health panel of the Senate Appropriations Committee, said the $25 billion figure was “certainly in the ballpark of what I’ve been talking to these agencies about and would expect we have a number that’s similar to that” in the bill Senate Republicans plan to release next week.

Mr. Blunt said he hoped a national plan would be ready by September and could potentially be rehearsed through the distribution of the flu vaccine this fall ahead of a coronavirus vaccine targeted for late December 2020 or January 2021.

A senior administration official said that subject-matter experts are expected to propose a plan for vaccine distribution to the Department of Health and Human Services. That plan will likely deploy the traditional pharmaceutical distribution networks for vaccines and potentially draw on support from the Defense Department, the official said.

One emerging divide is over how much the vaccine should cost the public. Democrats said the easiest way to make sure the vaccine is distributed as swiftly as possible would be to make it free for everyone, with the federal government using its purchasing power to buy all the doses needed to immunize the U.S. population. Republicans said it should be free for everyone who can’t afford, it as well as the most vulnerable and set at a reasonable price for others.

“The federal government has made clear that Covid-19 testing, treatment and a vaccine—when one is available—will be affordable for all Americans and free for those most vulnerable to Covid-19,” said Rep. Greg Walden of Oregon, the top Republican on the House Energy and Commerce Committee. Legislation passed by Congress in early March stated that when a vaccine is ready, it should be priced fairly.

Democrats said they are concerned about what pharmaceutical companies may say is a reasonable price, pointing to Gilead Sciences Inc.’s plans for its Covid-19 drug remdesivir. The company said in late June it will charge U.S. hospitals $3,120 for a typical patient.

“This is not affordable for your person on the street,” said Rep. Jan Schakowsky (D., Ill.) “There’s a lot of room for difference when it comes to what Big Pharma says and what we think is reasonable.”

Gilead has said that its drug should help reduce hospital costs by $12,000 a patient.

Under the Affordable Care Act, most insurers are required to provide routine vaccines at no out-of-pocket cost. Congress specified earlier this year that should include any emergency coronavirus vaccine once it has been approved by the Advisory Committee on Immunization Practices, a body that counsels the federal government on vaccine matters.

However, some health-insurance plans are exempt from those guidelines, including shorter-term plans that don’t have to comply with the ACA, whose enrollment has jumped since the Trump administration relaxed restrictions on them. And while many people losing their jobs in the economic recession sparked by the pandemic would be eligible for Medicaid or to enroll on the ACA exchange, millions are expected to remain uninsured.

In the Senate, where negotiations are heating up over the next aid package, a variety of lawmakers called for additional investment in a coronavirus vaccine. A group of 27 senators, led by Sen. Jack Reed (D., R.I.) and Sen. Susan Collins (R., Maine) sent a letter Wednesday to Senate leaders asking them to provide at least $5.6 billion in the next bill for states and local governments to ready the infrastructure needed to distribute the vaccine. Separately, Sen. Steve Daines (R., Mont.) sent his own letter calling for “robust funding” for the development and distribution of a vaccine.

Some lawmakers have questioned whether there is a need for additional funding. Congress already approved $6.5 billion to the Biomedical Advanced Research and Development Authority and $3 billion to the National Institutes of Health to support research and development for coronavirus treatments and vaccines.

“There is a lot of money that’s available,” said Rep. Michael Burgess of Texas, the top Republican on the health panel of the Energy and Commerce Committee. Mr. Burgess said he would be open to more funding “if someone can identify a potential shortfall,” but said he hadn’t been notified of any yet.

Published here.