SIOUX FALLS, S.D. (KELO) — COVID-19 is currently hitting South Dakota hard, with cases rising, and hospitals struggling under the weight of increased cases and staffing shortages. Clearly this is the upward slope of a new wave of the virus that we’re currently experiencing, but just which wave is this now?

According to Avera Health Chief Medical and Innovation Officer Dr. David Erickson, that’s a tricky question to answer.

“I think most people would define these waves as kind of a surge,” said Erickson when asked what exactly constitutes a wave. “Just a significant increase of the incidence of disease in the population.”

“Sometimes, to be honest with you, it’s hard to keep track of which wave we’re in,” added Erickson.

Overall, we’ve had multiple waves of COVID-19 so far, says Erickson. “Three, four or five depending on how you count them.”

As Erickson counts them, we’ve had three waves of COVID-19.

“I think we’ve had several,” he said. “We had the initial wave, we had the delta wave and now we’re in the Omicron wave. We clearly have had several waves here.”

Erickson talked more about the challenge of defining how many waves we’ve now faced. “[Its] probably almost more personal point of view really,” he said. “Some people count them a little different. We might count one wave as a single wave and some may have had kind of a peak — went down a little bit — come back up; some might count that as two, some count it as one.”

This can be illustrated by looking at trend data overtime, such as the chart below showing cases over time since January 2020.

Some could look at this and see 3 to 4 waves, while others may see as many as 8 or more. This most clear when looking at the time period surrounding November 2020 – January 2021. While the line of 7-day averages shows three distinct peaks, which some could view as three waves, others may see the overall rise of cases and describe that period as the peak of a single wave.

“I think so many people out there have an opinion on it that you’re going to hear a little difference of opinion on the wave and how many we’re in and where we’re at.”

Part of the reason Erickson sites for it being difficult to determine which wave we’re currently in is the fact that COVID-19 hits different parts of the country at different times.

“New York started their omicron wave earlier than we have,” he said. “They are showing signs that maybe that wave is peaking — where we’re still on an upswing.”

However you choose to define a wave, it is clear that the current one is a big one.

“Clearly with omicron variant you’re seeing a significantly higher rate of transmission,” said Erickson. “If you look at case-counts across the country, with the delta wave we had roughly 250,000 cases per day at the peak; right now with the omicron, we’re having 750,000 cases per day.”

Despite the numbers currently being seen, Erickson struck a note of optimism. “I think a lot of the knowledge and leading experts now believe that this most likely would be the last wave, and we’ll move from a pandemic to more [of] an endemic where you still have the virus circulating in the population, but you don’t have these large surges or waves that we’ve seen.”

That optimism also came tempered with a warning:

“With the omicron variant and the rate of transmission, it will find all people who are unvaccinated, and it’s also going to find initially probably 30-40% of people who are vaccinated and boosted — the difference is, those who are unvaccinated have a 10x higher risk of hospitalization and a 10x higher risk of death.”

Erickson said the other things we have learned is that the vaccines for COVID-19 are safe and that masks work.