MIDDLESEX CENTRE, ONT. -- Starting Wednesday, anyone who wants to get their first COVID-19 vaccine dose can just walk in to any of the region's four mass vaccination clinics.

The Middlesex-London Health Unit (MLHU) says the goal is to vaccinate as many people as possible this summer.

Health officials hope this will make it even easier for people to get their initial dose and be protected against COVID-19.

“If you have not yet had your first dose of COVID-19 vaccine, you can now walk into any area clinic, any time before 5 p.m. and get your shot,” said Dr. Chris Mackie, MLHU medical officer of health, in a statement. “Getting vaccinated is more important than ever. The common link we’re seeing among those who are becoming ill and sadly dying from COVID-19 is that they are not vaccinated.”

Walk-ins will be accepted up to an hour before closing at each clinic, with the limitation to ensure all vials of vaccine are used fully.

In addition to the mass vaccination clinics at the Wester Fair District Agriplex, North London Optimist Community Centre, Mount Brydges and Earl Nichols Arena -- walk-in pop-up clinics are being held around the region.

MLHU emphasizes need to take first available vaccine

The health unit is also reiterating the importance of taking the first mRNA vaccine available, after it says comments from the World Health Organization (WHO) were taken out of context.

Officials say WHO Chief Scientist Dr. Soumya Swaminathan was speaking out against a trend in the U.S. to offer mRNA vaccines to those who have already been fully vaccinated with another vaccine.

There are concerns this could divert vaccine supplies from unvaccinated people in developing countries to those who are already vaccinated in developed countries.

Both the province and MLHU say it is safe to mix vaccines, whether it's two mRNA vaccines like Pfizer and Moderna, or following an AstraZeneca dose with an mRNA dose.

“Studies from across Europe continue to indicate that mixing vaccines is safe and produces a strong immune response,” Mackie added. “Regardless of which vaccine you received for your first dose, getting a second dose as soon as possible is the most important thing you can do to prevent serious illness, hospitalization and potentially spreading COVID-19 to your friends or loved ones.”

Everyone 12 and over is being encouraged visit covidvaccinelm.ca to rebook their second-dose appointment at the shorter 28-day interval.