NewsLocal News


CU researchers, global partners model which COVID vaccine distribution strategies work best

Saving lives vs reducing spread
Posted at 1:09 AM, Dec 13, 2020
and last updated 2021-01-05 15:17:02-05

BOULDER, Colo. -- Medical workers are at the front of the line to receive the COVID vaccine.

But what about people who have already had the virus. Should they give up their spot in line and let others go first?

Researchers at the University of Colorado Boulder's BioFrontiers Institute are using mathematical models to help determine which distribution strategies will work best.

"When it comes to vaccines, there are two ways you can look at them. Both make a lot of sense," said Professor Dan Larremore, a computational biologist at the Institute.

Larremore, and lead author Kate Bubar, a PhD student in the Department of Applied Math in the IQ Bio program, teamed up with colleagues at Harvard and the University of Chicago, to look at different scenarios.

"You want to directly protect the most vulnerable people," he said. "That makes a lot of sense, but another thing that makes a lot of sense is, you should instead give the vaccine to people most responsible for all the transmitting."

The researchers found that prioritizing older adults saves the most lives, while prioritizing young adults reduces the most infections.

"In very few cases did vaccinating children first make sense," Larremore said.

The study also found there may be instances where it makes more sense to hold off administering the vaccine to part of the population until more supplies are available.

In communities where COVID had already infected large swaths of the population, prioritizing those who are “seronegative” or did not already test positive for the virus, could allow health agencies to stretch the vaccine farther and save more lives.
For instance, in New York City where 27% of people have already been infected, vaccinating one in five people over age 60 could bring mortality down by 73%.

“If transmission is rampant, and hospitals are being overwhelmed, then directly protecting those who are at the highest risk for severe outcomes is the best way to save lives and decrease the stress on our healthcare system,” said Bubar. “But, if instead, transmission is relatively low in a given area then prioritizing those who have the most contacts would be better— provided that the vaccine blocks transmission.”

That's one of the unanswered questions.

Do the vaccines keep the virus from replicating inside you, or do they just keep you from getting sick?

And if the virus can still replicate inside you, can you spread it to others?

Dr. Anthony Fauci, director of the National Institute of Allergy & Infectious Diseases, said, "We don't know the answers to those last two questions, a) does it protect against infection, and b) if you are infected, does it render the viral load so low that you're not transmitting it to anyone."

Larremore said that means even after getting vaccinated, people should continue wearing masks, and continue social distancing.

"It's not a time to take our foot off the gas," he said. "It's really a time, with cases and hospitalizations higher than ever, to really adhere to those safety protocols we know work well as the vaccine is slowly rolled out."

When asked how long it will be before we see a return to "normalcy," Larremore replied, "I'm hopeful that as the vaccine gets rolled out across the U.S., we'll see something like a return to normal by late 2021 or mid 2022. A lot depends on vaccine supply and a lot depends on how good we are at controlling the virus in the community. There's a lot that we can do to prevent the spread even before the vaccine gets widely rolled out."