Without masks and a vaccine, we could reach Herd Immunity from COVID-19, but deaths would skyrocket. We break down the science of it.
Although it may seem like much of the state has had the coronavirus, fewer than 11% of Hoosiers have been infected to date, a study from researchers at Indiana University’s Fairbanks School of Public Health estimates.
That amount is far from the 70% needed to achieve herd immunity, the point at which enough members of a population have been exposed to a virus or bacteria to confer some protection for the rest of the community.
And achieving herd immunity without a vaccine could prove to be a deadly venture, an IU scientist said.
The Fairbanks study, which has been looking at statewide prevalence of infection, found that as of early October 7.8% of people living in Indiana have been infected with the novel coronavirus. With cases rising rapidly throughout the months of October and November, the researchers extrapolated that as of last Friday 10.6% of people have been infected.
That amount is only about one-seventh of the number of people that would need to be infected to achieve herd immunity.
With more than 5,200 deaths already, achieving herd immunity without a vaccine would lead to an additional 13,000 deaths for the state, said Dr. Nir Menachemi, lead scientist on the study and Fairbanks endowed chair.
Richard M. Fairbanks School of Public Health along with the Indiana State Department of Health conducted testing to measure the spread of COVID-19 at a mobile site on the north side of Indianapolis. Photo taken Wednesday, April 29, 2020. (Photo: Liz Kaye, Liz Kaye / Indiana University)
That number refers only to non-nursing home deaths, he said. More than half of the state’s coronavirus deaths have been in nursing home residents.
“Comparatively that’s many times more deaths than have already occurred in Indiana,” Menachemi said. “Pushing to achieve herd immunity without a vaccine simply risks losing many lives.”
The most recent wave of the study also looked at the different mortality rates of COVID-19 for different age groups, not including people who live in nursing homes.
Those under age 30 had a 0.005% chance of dying. The risk rose to 0.04% for those in the 30 to 49 year old age range and 0.44% for those between the ages of 50 to 64, or 1 in 224.
The fatality rate shot up to 2.31% for those over the age of 65, with about 1 in 43 infected, the study found.
At the same time, people over age 65 were the least likely to have been infected. Just over 4% of people in this age range were estimated to have been infected as of the beginning of October, compared with nearly 12% of those age 30 to 49 years old. Six weeks later those percentages increased to nearly 7% and 16.5% for those age ranges.
In early October, the Indiana Department of Health listed around 124,000 cases of coronavirus on its online coronavirus dashboard, under 2% of the population.
But the Fairbanks study includes not just those who have tested positive after experiencing symptoms or an exposure but tries to correct for those who are infected with the virus but do not realize it.
The first wave of the study found that up to 40% of people who are infected with coronavirus do not even know that they are carrying the germ. That phase, conducted in late April, found a population prevalence of 2.8%.
A second phase in June found lower levels of active infection and a higher rate of people who tested positive for antibodies, suggesting the virus was slowing its spread.
Fairbanks researchers are planning another wave of the study in 2021.
Read or Share this story: https://www.indystar.com/story/news/health/2020/11/25/indiana-covid-study-reveals-risk-planning-herd-immunity/6422207002/