Nav: Home

How well do vaccines work? Research reveals measles vaccine efficacy

March 07, 2019

The recent measles outbreaks across the country emphasize the importance of vaccinations.

WATCH VIDEO: https://video.vt.edu/media/0_vltvihxh

"For many infectious diseases, we rely on herd immunity to prevent outbreaks of vaccine-preventable infections. Herd immunity is the protection of the 'herd,' our population, by preventing infections in the vast majority people," said Kate Langwig, an infectious disease ecologist at Virginia Tech. "We can calculate the percentage of the population that needs to be vaccinated to prevent diseases from spreading and maintain herd immunity. For some pathogens, like measles, the number that needs to vaccinated is very high because the measles virus spreads so easily."

Langwig, an assistant professor in the Department of Biological Sciences in the College of Science at Virginia Tech, is researching ways in which vaccine efficacy can be improved.

The measles vaccine has been shown to have 97 percent efficacy, but "understanding the circumstances that contribute to vaccine ineffectiveness can help to better protect populations," Langwig said.

Langwig and her lab ran mathematical modeling simulations to determine if vaccine efficacy might be lower when individuals are exposed to high pathogen doses, and when individuals vary in their susceptibility.

For example, if you have been vaccinated against the measles, but someone sneezes very close to your face, or you're caring for a sick kid who is sneezing, coughing, etc., are you more likely to get sick? In addition, if you're run down (maybe from chasing that kid the week earlier), are you more likely to get infected even if you've been vaccinated?

Langwig and her lab found in their simulations that vaccines are predicted to be less effective at higher pathogen doses and when individuals in the population have similar susceptibility. These findings were recently published in Scientific Reports.

"Susceptibility, meaning how likely an individual is to get infected, is also important. Individuals that are younger or have poor nutrition can be more likely to get infected, even if they have been vaccinated. We found that populations that have more variable susceptibility have higher vaccine efficacy," said Langwig, an affiliated faculty member of the Global Change Center, an arm of the Fralin Life Science Institute.

Langwig and her lab were interested in validating their simulations with some real-world data, so they did a systematic literature review with help from Virginia Tech undergraduate researchers to determine whether there were examples of diseases where vaccines efficacy is reduced at high doses.

"What we found was a bit of a shock - there are a very small number of studies that test whether vaccines are effective across multiple pathogen doses. We reviewed almost 6,000 articles and identified only about a dozen studies that had tested vaccines across multiple pathogen doses. Within those few studies, the pattern was generally consistent with our simulation - vaccine efficacy tended to be lower at high pathogen doses," said Langwig.

They did find that some vaccines did offer complete protection regardless of pathogen dose in several model organisms, suggesting that not all vaccines are less effective when individuals are exposed to high doses.

Extrapolation to human systems should be done with care, but this research helps increase the understanding of host susceptibility, pathogen dose, and vaccine efficacy.

"One thing that surprised us is that many scientists are vaguely aware that vaccines might fail at high pathogen doses, but there were a very small number of studies that had ever examined this," said Langwig.

Langwig is currently collaborating with another lab to test vaccine efficacy and different pathogen doses in a species of rainbow trout. They will continue to design mathematical models to test predictions in real-world situations to determine how populations can be further protected.
-end-


Virginia Tech

Related Vaccines Articles:

Misinformation on vaccines readily available online
Parents researching childhood vaccinations online are likely to encounter significant levels of negative information, researchers at the University of Otago, Wellington, have found.
Battle with the cancer: New avenues from childhood vaccines
A new research from the University of Helsinki showed for the first time how the pre-immunization acquired through common childhood vaccines can be used to enhance therapeutic cancer treatment.
Personalized cancer vaccines
The only therapeutic cancer vaccine available on the market has so far showed very limited efficacy in clinical trials.
Doubts raised about effectiveness of HPV vaccines
A new analysis of the clinical trials of HPV vaccines to prevent cervical cancer raises doubts about the vaccines' effectiveness.
Egg-based flu vaccines: Not all they're cracked up to be?
Flu season is underway in the Northern Hemisphere, sickening millions of people and in rare cases, causing hospitalization or death.
You're probably not allergic to vaccines
Five facts about allergies to vaccines, pulled together by two McMaster University physicians.
Micromotors deliver oral vaccines
Vaccines have saved millions of lives, but nobody likes getting a shot.
Vaccines not protecting farmed fish from disease
The vaccines used by commercial fish farmers are not protecting fish from disease, according to a new study.
Bioengineers imagine the future of vaccines and immunotherapy
In the not-too-distant future, nanoparticles delivered to a cancer patient's immune cells might teach the cells to destroy tumors.
Pneumonia: Treatment with vaccines instead of antibiotics
A properly functioning immune system is key to resolve bacterial pneumonia.
More Vaccines News and Vaccines Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Climate Mindset
In the past few months, human beings have come together to fight a global threat. This hour, TED speakers explore how our response can be the catalyst to fight another global crisis: climate change. Guests include political strategist Tom Rivett-Carnac, diplomat Christiana Figueres, climate justice activist Xiye Bastida, and writer, illustrator, and artist Oliver Jeffers.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Speedy Beet
There are few musical moments more well-worn than the first four notes of Beethoven's Fifth Symphony. But in this short, we find out that Beethoven might have made a last-ditch effort to keep his music from ever feeling familiar, to keep pushing his listeners to a kind of psychological limit. Big thanks to our Brooklyn Philharmonic musicians: Deborah Buck and Suzy Perelman on violin, Arash Amini on cello, and Ah Ling Neu on viola. And check out The First Four Notes, Matthew Guerrieri's book on Beethoven's Fifth. Support Radiolab today at Radiolab.org/donate.