PHOENIX — The past two flu seasons were the worst the state has ever seen, but this season has seen a 93% decrease in the number of cases and is one of the lowest on record — all likely due to COVID-19.
By this point last season, there were more than 19,000 laboratory confirmed cases of flu in the state, but there are just 815 in the 2020-21 season. During the week beginning Jan. 17, there were only 38 cases of flu reported, compared to the 39,788 COVID-19 cases confirmed during the same time period.
“It’s a dominant organism in the community,” said Dr. Shad Marvasti, an associate professor at the University of Arizona and physician who has specialized in chronic diseases. “When one virus becomes the dominant organism in the community, it doesn’t let other viruses take hold and gain a foothold.”
COVID-19 has proven to be far more contagious than the flu, despite the similar ways both viruses spread. In addition, new variants of COVID are proving to be even more contagious as well.
One of those new variants, which first appeared in the United Kingdom, has recently been discovered in Arizona.
Arizona isn’t alone in seeing extremely low flu cases and high COVID-19 cases, leading Marvasti and others to theorize that COVID-19 is taking over the flu within viral ecosystems.
Southern and Latin American countries have been hit hard by COVID-19 and some areas have not had as many prevention measures in place for the virus, but have had very low rates of flu as well.
“It’s a little bit of a conundrum to me,” Richard J. Webby, PhD, an expert in influenza and a member of the Infectious Diseases Department at St. Jude Children’s Research Hospital and the World Health Organization’s Vaccine Composition Team said about the two statistics.
“I think there is probably something behind that hypothesis that when one virus is going gangbusters that it makes it difficult for another virus to squeeze in,” Webby said, adding that he thinks there may be more to what is going on.
In other parts of the world, flu rates have been low, but vaccination rates for the flu have also been higher than they have ever been. In those places, enhanced public safety measures have also been in place, such as social distancing, mask requirements and closures of certain businesses.
Those mitigation measures may have been a help here, as well, Marvasti said, adding that research into which theories on why the flu has seen a decrease in Arizona and across the globe will take some time.
Flu vaccination rates in the United States are at the highest levels they have ever been, according to data from the Centers for Disease Control and Prevention. However, the total number of vaccines administered in Arizona is not available.
“The number of publicly supplied vaccines through the Vaccines For Children (VFC), Vaccines For Adults (VFA), and Children’s Health Insurance Program (CHIP) programs has been 251,950 doses to date with 236,600 additional doses available for order,” Holly Poynter, spokeswoman for the Arizona Department of Health Services said to Arizona Mirror. “Please note that this is not representative of total vaccination efforts in the state.”
Nationally, more than 193 million vaccines have been distributed, up from the 174 million the season prior.
However, Arizonans generally have low vaccination rates, including the flu vaccine. Less than half of all Arizonans got the flu shot last season.
A slowdown of international travel could also be another reason for the lower number of flu cases, Webby said.
“I don’t think it’s any one factor that is knocking the flu back,” Webby said.
What is also unclear is if COVID-19 will be here to stay as a seasonal illness, much in the way the flu is. If so, then the main concern will be on learning about how the virus mutates much like how the flu mutates, Marvasti said.
“Viruses mutate all the time, and it’s because they have imperfect mechanisms of replication,” Marvasti said. The flu replicates much faster than other viruses, which tends to mean that the flu vaccine has a success rate of around 60%. The current COVID-19 vaccines have an effective range of up to 90%, in large part because the virus has mutated slowly, and it ways that haven’t yet affected how the vaccines train the body to fight off the illness.
“This is sort of crystal ball stuff cause no one knows for sure,” Webby said. In 2009, during the Swine flu pandemic, the virus began to calm down once vaccines began to be implemented, something Webby is hoping for with the current pandemic.
The world already faces several seasonal coronaviruses, and COVID-19 could possibly join their ranks, Webby said.
“This is not precedent-setting for coronaviruses,” he said.
The way COVID-19 has mutated so far also gives us a glimpse at what the future may hold.
RNA, or ribonucleic acid, is a protein that in viruses carries genetic information. In flu viruses, the genes are carried on individual pieces of RNA, while COVID-19 carries its genes in a single strand of RNA.
Since the flu carries its genes in so many places, the virus mutates often and quickly, giving flu vaccines a lower effective rate — particularly compared to the current COVID-19 vaccines. Researchers believe that COVID-19 will mutate less frequently, Webby said.
“It gives me some hope that we aren’t going to be in the same flu boat with coronavirus,” Webby said.
But as effective as the early COVID-19 vaccines have been, Marvasti said they aren’t a silver bullet. If there is too much community spread of the virus in places like Arizona and elsewhere, the virus will begin to mutate before a vaccine has a chance to gain a foothold in the community.
“The fact that we are just limiting ourselves to vaccines with a virus that is so deadly and has so many potentials for adverse impacts makes no sense to me,” he said. “We don’t want to just try to vaccinate our way out of it.”
As for what will happen to the flu, some scientists are finding interesting correlations between how the two viruses interact. One study found that an earlier flu infection might provide some sort of cross-protection against the virus, while another study comparing flu and COVID-19 patients found COVID-19 to be far deadlier among the elderly and children alike.
The current ways the virus is mutating is also to adapt to its current hosts: humans.
A recent strain that mutated in South Africa did so in a way to adapt to human immune responses, while a mutation that originated in the United Kingdom is adapting to transmit more effectively, which, according to Webby, also points to it’s likely origins.
“We need to approach it from all these angles,” Marvasti said of COVID, adding that the United States also needs to look at other health issues such as obesity and diabetes and how that is impacting the mortality rates of Americans and those who get COVID.
French research appears to back up his claims. A study of flu and COVID-19 patients in France found that patients who were often admitted to the hospital or died from the virus also had underlying health issues that impacted their recovery such as obesity, heart disease, diabetes and chronic respiratory issues.
“I think having this holistic approach is important more now than ever,” Marvasti said about how the medical profession should approach viral outbreaks going forward.