DES MOINES, Iowa — Signs of normalcy are returning across America following a holiday weekend of Independence Day parades and gatherings, but epidemiologists warn the wrath of COVID-19 could return in the form of the highly transmissible delta variant.
In each of the past two weeks, the delta variant accounted for more than half of positive coronavirus tests that included other variants of the virus, according to the Iowa Department of Public Health.
The strength of the variant appears to be showing in not just Iowa, but surrounding states including Missouri, Kansas, and Nebraska — as it accounts for 80.7 percent of all four states’ positive cases, according to the Centers for Disease Control and Prevention.
The number of fully vaccinated Iowans surpassed 1.5 million this week, while more than 93,000 Iowans should be getting their second dose within the coming weeks. That equates to about 45.9 percent of Iowans, a number health officials say still needs to be higher in order to reach herd immunity.
Herd immunity has been generally estimated to be around 70 to 80 percent of the population. Some counties in Iowa have vaccination rates as low as 28 percent, with 19 counties being below 40 percent.
Dr. Megan Srinivas, an infectious disease expert based in Fort Dodge, said the delta variant will be able to thrive in those communities where the rates are too low to achieve herd immunity.
“This virus is extremely intelligent. It utilizes evolution to change itself to try to beat us when we’re trying to get on top of it. And that’s why herd immunity is so important,” she said. “If we don’t give the virus a chance to jump from person to person to change itself to beat the vaccines and the medicines we have out there, we can stop it.”
Srinivas said already, the delta variant is not just more lethal but far more contagious than the original strand of the coronavirus. She said SARS-COV2 strain had an “R naught” rate of 2.3 to 2.6 — the “R naught” is how contagious a virus is — meaning each person that got infected was likely to spread to another 2.3 to 2.6 individuals. Now, the delta variant has an infection rate of 5 to 8, meaning each individual who contracts it could spread it up to 5 or 8 others.
“But if we don’t get enough people vaccinated, that virus can continue to move from person to person. And every time it copies itself, it replicates. It’s able to have a chance to change to make itself stronger, so it can beat what [vaccine] we already have out there,” Srinivas said.
Right now, studies show the current COVID-19 vaccines still have a high protection against the delta variant, but not as high of an efficacy rate as against the original strain of the virus. Srinivas and other public health experts fear a new mutated version of the virus could evolve resistance to current vaccinations.
“We’ll see other variants pop up as well if we allow it the space to do so. In fact, we already have the delta plus variant that’s now come about, which is potentially even more transmissible than the delta variant,” she said.