Minnesotans now have their first shot at signing up for a COVID-19 vaccine trial — with Bloomington-based HealthPartners announcing Wednesday that it is recruiting up to 1,500 adults for AstraZeneca’s Phase III study.

HealthPartners is the fifth site in the trial to start recruiting participants, who would receive either the experimental vaccine or a non-medicating saline injection for comparison in two doses, and would then commit to a series of nine checkup visits over two years.

Earlier, smaller trials showed evidence of safety and immunity, said Dr. Charlene McEvoy, a HealthPartners pulmonologist and lead researcher for the local site.

“What we don’t know is, does it work well in everyone? Is it well tolerated across the board?” McEvoy said. “The biggest question is, how long does that immunity last?”

HealthPartners’ selection as one of 62 U.S. trial locations reflects the providers’ history of clinical research, but also a bittersweet reminder that COVID-19 has spread broadly in Minnesota. Trials generally only recruit in states where there is enough virus activity to prove that an experimental vaccine works.

Minnesota as of Tuesday had recorded 76,355 lab-confirmed infections with the coronavirus that causes COVID-19, and 1,823 deaths. Despite some signs of viral activity leveling off in early August, the state has seen its confirmed infection rate double from 6 new cases per day per 100,000 people on June 16 to 12 cases now.

No Minnesota sites were selected by Moderna or Pfizer for their Phase III COVID-19 vaccine trials. Minneapolis-based Allina Health is pursuing participation in a vaccine trial by the Janssen Pharmaceutical Companies of Johnson & Johnson later this year.

The AstraZeneca experimental vaccine, developed by researchers at Oxford University in England, seeks to boost both production of antibodies in response to the SARS-CoV-2 virus and of T-cells that help the body adapt and respond to infections.

McEvoy said the earlier safety studies showed some potential for mild side effects such as aches or mild fever — akin to what some people experience each year with seasonal flu shots. People interested in volunteering can go to the HealthPartners website for recruitment information, but McEvoy said the trial is particularly interested in people at higher daily risk of exposure to the virus. That includes people with close contact jobs such as waiters.

The trial also is seeking minorities because of the higher rate of severe COVID-19 and deaths among people who are Black, Hispanic and American Indian. Another goal is for a quarter of enrollees to be 65 or older, because age has proved to be an independent risk factor for severe COVID-19 outcomes.

People in the trial who test positive for COVID-19 would participate in remote monitoring to see when symptoms develop and if they are severe, McEvoy said. They would receive take-home monitoring equipment for their temperature, breathing rate, heart rate and oxygen level.

“Maybe the vaccine won’t prevent illness but it will make it much less severe” in some people, she said.

McEvoy added that some experimental vaccines might prove more effective in certain populations than others. HealthPartners is seeking to complete recruitment in eight weeks. AstraZeneca’s goal is to have initial safety and effectiveness results by the end of the year or early 2021.

The trial is blinded, meaning neither participants or researchers know who has received the experimental vaccine or the placebo. Participants would receive up to $1,000 to compensate for travel time and other expenses related to required clinical visits, which would include regular blood draws to check for antibody levels and indications that the vaccine is working.