Issue: October 2011
October 01, 2011
1 min read

Herd protection may be playing an important role in reducing outbreaks

51st ICAAC

Issue: October 2011
You've successfully added to your alerts. You will receive an email when new content is published.

Click Here to Manage Email Alerts

We were unable to process your request. Please try again later. If you continue to have this issue please contact

CHICAGO — The recent outbreaks of measles and pertussis in the United States demonstrate that vaccination rates remain subpar, but the ripple effects could be far worse if it were not for herd protection, according to a speaker here.

“We aren’t quite at the peak threshold we need to be for vaccinations, but hopefully we’ll maintain current rates enough to minimize the time for spread,” said Larry K. Pickering, MD, who is an Infectious Diseases in Children Editorial Board member.

Larry K. Pickering
Larry K.

Pickering addressed an audience at the 51st Interscience Conference on Antimicrobial Agents and Chemotherapy. He discussed two recently published papers on herd immunity (See references below), calling them both “very good reading.” He said the common theme of both papers is that the risk for infection among susceptible people is reduced by the presence of immune people.

According to Pickering, it is particularly important for pediatricians to read about herd immunity now, in the midst of outbreaks, to answer questions from parents about the importance of vaccination. Pickering said there are a variety of concerns surrounding vaccinations, and parents’ responses to that may be to have their child partially vaccinated, or not at all, under the belief that “I don’t need to get my child immunized because everyone else is.”

He said there are many reasons why parents are reluctant or refuse to vaccinate, including concern over safety and efficacy of vaccines, lack of trust in the government and the perception that their children were not at great risk.

However, these stereotypes are often based on hype, Pickering said, and the data show that vaccine misinformation has led to drastic increases in vaccine-preventable deaths and diseases. As an example, he cited a paper that showed that the rates of immunization declined after a paper in The Lancet suggested a connection between vaccinations and autism — which was later retracted by most of the researchers’ on the paper — and measles rates and deaths soared in the United Kingdom.

Pickering said researchers have found that vaccination rates of at least 93% can ensure herd immunity against pertussis, so encouraging vaccination, particularly in those areas hardest hit by the recent outbreak, is key.

For more information:

  • Pickering LK. #62. Hot Topics in Vaccines. Presented at: 51st ICAAC; Sept. 17-20, 2011; Chicago.
  • Clemens J. Lancet Infect Dis. 2011;11:482-487.
  • Fine P. Clin Infect Dis. 2011;52:911-916.
Twitter Follow the on Twitter.