SALT LAKE CITY – The flu rate in Utah and the United States remains low, a trend first seen months ago in the southern hemisphere of the world.
While influenza infections are low, COVID-19 cases are still on the rise across the country: At least nearly 1,000 are reported in Utah every day since the end of September.
For some, the numbers don’t add up – if public health measures protect people from the flu and COVID-19, why are there new cases of coronavirus and the flu rate so low?
According to Dr. Eddie Stenehjem, infectious disease specialist at Intermountain Healthcare, the answer is actually quite simple.
“You had low flu coming into the US, everyone wore masks, you have social aloofness and you have had the high rates of (flu) vaccinations,” Stenehjem said in a Q&A this week. “We really hope that will allow us to get through the flu season without seeing any significant flu activity.”
Why have COVID-19 cases not come down? This is what Stenehjem said.
The new coronavirus is more contagious than the flu.
Scientists use a mathematical term called R0 (pronounced R-zero) to describe how easily a disease or virus spreads from person to person in a community.
Experts have calculated that the mean R0 of COVID-19 is between 2 and 4, meaning that an infected person can spread the disease to two or more people, the World Health Organization said in a June report. In comparison, the mean R0 for flu during the 1918 Spanish flu pandemic was roughly between 1 and 2, according to an article published in BMC Medicine.
The number can vary widely even between different areas and states and depending on the outbreak.
The R0 is fluid and does not give a complete picture of how contagious a disease is, but it does provide a starting point despite its many limitations. However, one thing remains clear: COVID-19 is more contagious than the flu.
It was already in the community
COVID-19 has been spreading in communities since spring, meaning that when winter arrived, the virus was already widespread, Stenehjem explained.
The flu, on the other hand, is usually brought into a community from the Southern Hemisphere. But with a low rate of the flu there, it never really got here, he said.
About this time last year, Intermountain saw about 80-100 flu cases daily. This year, the healthcare industry has reported just a handful of cases in recent months.
Intermountain hospitals are actively looking for flu cases with extensive testing, Stenehjem said.
“It’s not for lack of sight, it’s just that we don’t see the flu,” he said.
The Utah Department of Health also tracks flu cases in the state, and from the week of December 13-19, cases remained low. So far this flu season, which began in early October, a total of seven people with the flu have been hospitalized.
“We really don’t see many other viruses circulating in Utah,” said Stenehjem. “COVID-19 is by far the most prominent respiratory viral infection seen here in Utah.”
We do not have a COVID-vaccinated population
In recent weeks, COVID-19 vaccines have been rolled out statewide to those eligible to get it in the first stage – but the population is nowhere near herd immunity.
Flu vaccinations, on the other hand, have largely risen across the country.
The U.S. Centers for Disease Control and Prevention reported that 192.3 million doses of flu shot have been distributed since last week, and it is possible that up to 198 million doses will be distributed in the 2020-2021 season. That number is up significantly from 2019, when 174 million were distributed over the 2019-2020 flu season.
According to the Utah Department of Health, more flu vaccinations appeared to have been reported for different age groups this year than last year.
However, it is important to note that some age groups did not follow the pattern and reported lower flu vaccination rates than in 2019, such as the 6 months to 4 years age group.
Overall, flu vaccinations seem to have increased nationwide from last year, contributing to low flu rates, according to Stenehjem.
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Lauren Bennett