Drug costs will go up for middle- and high-income seniors, while more seniors will qualify for a low-income drug program under new changes unveiled Thursday in the provincial government's 2016 budget.

This change would expand the pool of seniors who are eligible for the Ontario Drug Benefit program.

The proposals include raising the income threshold to qualify for it to $19,300 from $16,018 for single seniors, and to $32,300 from $24,175 for senior couples.

Low-income seniors who receive the benefit will continue to pay a $2 co-payment per prescription with no annual deductible.

Meanwhile, seniors who are at or above the updated income thresholds will see their costs go up.

The annual deductible under the benefit for these seniors will increase from $100 to $170, while the co-payment ­­-- or the fee paid per prescription -- will increase by $1 to $7.11.

Changes are part of larger proposed overhaul

Health department officials could not say what the cost, or savings, will be under the changes before they roll out on August 1.

However, the budget document notes that none of the province's six public drug programs, which have various eligibility and co-payment  rules, have been updated in two decades, and the changes are the first step in a planned overhaul of all of them.

Asked Thursday why the government is raising drug costs for middle-income seniors, Health Minister Charles Sousa said the province's drug benefits program has to be sustainable.

"We are supporting seniors right across the board to access more medicine," Sousa told reporters. "We are the most generous in Canada for that and it hasn't changed in 20 years."

NDP Leader Andrea Horwath blasted the changes, saying the increase in drug costs will be especially hard on seniors living on fixed incomes.

"I think seniors are going to be shocked. They're going to be worried," Horwath told reporters. "The vast majority of seniors in the province are living in fixed incomes, and their fixed incomes are not going up."

The government plans to introduce a "redesigned public drug program by 2019," the budget states, to ensure "long-term sustainability while ensuring access to prescription drugs for people who need them."

The Liberals are planning to launch public consultations on the drug-program overhaul this spring.

Another health care change for seniors is a move to help prevent shingles in Ontarians aged 65 to 70. Ontario will now cover the cost of the shingles vaccine, about $170, for all residents in this age group.