When will we have a safe, effective coronavirus vaccine? It's the big question on everyone's mind as we head into our eighth month of social distancing, mask-wearing, and economic instability.

While there's no guaranteed timeline for vaccinating Americans, some health experts are optimistic that a vaccine could be made available in early 2021 to healthcare workers, first responders, and our country's most vulnerable: the elderly. But what will a coronavirus vaccine cost Medicare enrollees, many of whom live on a fixed income of Social Security and little more?

The good news is that a coronavirus vaccine will likely end up being free for seniors on Medicare. But believe it or not, a no-cost vaccine technically isn't a given.

Nurse injecting older person.

Image source: Getty Images.

What will seniors spend to safeguard their health?

The Coronavirus Aid, Relief and Economic Security Act, which was signed into law in late March, stated that Medicare enrollees would not bear any costs to get vaccinated against COVID-19 once that option became available. But under current Medicare rules, that provision only applies to a vaccine that undergoes the standard approval process.

Because the U.S. has struggled to get the coronavirus outbreak under control, and because that COVID-19 has sickened and killed so many people, lawmakers intend to make a vaccine available to the public under an Emergency Use Authorization provision, which breaks from the standard approval protocol. That could prove to be a sticking point with Medicare coverage.

For this reason, the Trump administration is seeking to implement a regulatory change that would allow Medicare enrollees to receive a no-cost coronavirus vaccine approved under Emergency Use Authorization. This change would also apply to Medicaid beneficiaries.

Seniors on Medicare already struggle to keep up with their healthcare costs, especially as Part B premiums continue to rise from year to year. Many older Americans are feeling particularly squeezed this year due to the impact of the pandemic, making the cost of a vaccine exceptionally burdensome.

When will a vaccine become available for seniors?

There are multiple big players in the coronavirus vaccine race right now, but all eyes are on two major contenders: the Pfizer (PFE 1.80%) and BioNTech (BNTX -0.40%) duo, and Moderna (MRNA -0.87%). Both expect to file for Emergency Use Authorization by late November. There will then be a lengthy review process. If all goes well, seniors could start lining up to get vaccinated during the first quarter of 2021, along with healthcare professionals and first responders.

Many Medicare beneficiaries live on a very tight budget. Given the importance of protecting seniors from a potentially deadly virus, it's imperative that cost not be a barrier to getting vaccinated.