CHICAGO — Nearly 60% of the U.S. population have COVID-19 antibodies from infection and over 100 million people have been fully vaccinated and boosted, according to Centers for Disease Control and Prevention data. Researchers are trying to determine just how much COVID-19 antibodies, whether from infection or vaccination, fade over time.
Alan Landay, a scientist who studies immunity and emerging pathogens, is himself one of the subjects of a large-scale two-year study measuring COVID-19 vaccine antibody levels over time.
“I have not had COVID. And so, it's been very intriguing to see how my immune system has reacted,” said Landay.
With mask mandates and social distancing disappearing, many may be wondering how much their immunity has dropped off and whether they’ll need even more boosters.
“What does it mean to me as an individual living in society, traveling, being among all my friends, my family, my relatives?” asked Landay.
Dr. James Moy, an associate professor of immunology at Rush University Medical Center in Chicago, is trying to answer those questions. Since the first vaccines rolled out, he’s been tracking 1,100 health care workers like Landay, post-vaccination.
“We started drawing their blood for weeks after the second dose of the vaccine. And we've been drawing the blood every three months from there to see how long the antibodies last,” said Moy.
Moy said antibodies eventually drop significantly following a second shot.
“In our research looking at people's antibody levels at five months out, they've already dropped 80% from the peak levels,” he said.
“There's something strange about coronavirus and the vaccines that help prevent it that limit the length that the immunity lasts,” said Dr. Robert Murphy, executive director of the Havey Institute for Global Health at Northwestern University Feinberg School of Medicine.
Recently released data from the CDC sheds further light on just how much.
A double dose of the Johnson & Johnson vaccine remains 30% effective between two and four months after your shots. One dose of Johnson & Johnson and one of an mRNA shot from Pfizer or Moderna is 55% effective. And three doses of an mRNA shot are 63% effective between two to four months out.
“If you decide, ‘I'm not taking any more of these boosters, I've had enough.’ Well, guess what? In two years, your immunity is going to be basically nothing,” said Murphy.
Moy’s research shows that after a booster antibody levels do go up again and appear to drop much slower.
“I looked at my blood some six months later, it had fallen down almost tenfold before I was getting my booster. Then I got boosted and went up another tenfold,” said Landay.
But antibodies don’t tell the whole story.
“T-cells are very important against viruses and perhaps more important than antibodies. And unfortunately, we don't have quick lab tests to assess T-cell function,” said Moy.
Another looming question is how mutations will affect protection over time. Data already shows COVID reinfections occurring more frequently, in some cases more than once in less than 90 days.
“That depends on how quickly the virus mutates into the next variant,” said Moy. “So, the quicker it mutates and then your immune response is not as good against a variant, then yes, you'll get another infection.”
“It's just mutating around all the protection,” said Murphy.
As for future protection, both Moderna and Pfizer are developing brand new versions of their vaccines that are meant to replace boosters.
“You get a different flu shot and the same thing for COVID. We're going to get different coronavirus vaccines probably periodically, maybe even once a year,” said Murphy.
The hope is to provide stronger, longer-lasting protection against the original virus and any new variants that emerge.