Featured Research

from universities, journals, and other organizations

Did seasonal flu vaccination increase the risk of infection with pandemic H1N1 flu?

Date:
April 7, 2010
Source:
Public Library of Science
Summary:
In September 2009, news stories reported that researchers in Canada had found an increased risk of pandemic H1N1 influenza in people who had previously been vaccinated against seasonal influenza. Their research, consisting of four different studies, has now undergone further scientific peer review.

Did seasonal flu vaccination increase the risk of infection with pandemic H1N1 flu?

In September 2009, news stories reported that researchers in Canada had found an increased risk of pandemic H1N1 (pH1N1) influenza in people who had previously been vaccinated against seasonal influenza. Their research, consisting of four different studies, has now undergone further scientific peer review and is published in the open access journal PLoS Medicine.

Did previous vaccination against seasonal flu increase the risk of getting pH1N1 flu? Based on these studies -- conducted by a large network of investigators across Canada led by Principal Investigator Danuta Skowronski of the British Columbia Centre for Disease Control in Vancouver, in collaboration with provincial leads Gaston De Serres in Quebec, Natasha Crowcroft in Ontario and Jim Dickinson in Alberta -- the answer remains: "possibly."

In a school outbreak of pH1N1 in spring 2009, people with cough and fever were found to have received prior seasonal flu vaccination more often than those without. Several public health agencies in Canada therefore undertook four additional studies during the summer of 2009 to investigate further. Taken together, the four studies included approximately 2,700 people with and without pH1N1.

The first of the studies used an ongoing sentinel monitoring system to assess the frequency of prior vaccination with the 2008-09 seasonal vaccine in people with pH1N1 influenza (cases) compared to people without evidence of infection with an influenza virus (controls). This study confirmed that the seasonal vaccine provided protection against seasonal influenza, but found it to be associated with an increased risk of approximately 68% for pH1N1 disease.

The further 3 studies (which included additional case-control investigations in Ontario and Quebec, as well as a transmission study in 47 Quebec households where pH1N1 influenza had occurred) similarly found between 1.4-2.5 times increased likelihood of pH1N1 illness in people who had received the seasonal vaccine compared to those who had not. Prior seasonal vaccination was not associated with an increase in hospitalization among those who developed pH1N1 illness.

These studies do not show whether there was a true cause-and-effect relationship between seasonal flu vaccination and subsequent pH1N1 illness (as might occur if, for example, the seasonal vaccine modified the immune response to pH1N1), or whether the observed association was not a result of vaccination, but was instead due to differences in some unidentified factor(s) among the groups being studied.

If the findings from these studies are real they raise important questions about the biological interactions between pre-existing and novel pandemic influenza strains. The researchers note, however, that the World Health Organization has recommended that pH1N1 be included in subsequent seasonal vaccine formulations. This will provide direct protection against pH1N1 and thereby obviate any risk that might have been due to the seasonal vaccine in 2009, which did not include pH1N1.

In an accompanying commentary in PLoS Medicine, Lone Simonsen and Cécile Viboud, who were not involved in the studies, write: "Given the uncertainty associated with observational studies, we believe it would be premature to conclude that increased the risk of 2009 pandemic illness, especially in light of six other contemporaneous observational studies in civilian populations that have produced highly conflicting results." They conclude that "this perplexing experience should teach us how to best react to disparate and conflicting studies and prepare us for the next public health crisis, so that we can better manage future alerts for unexpected risk factors."

Funding: This project was funded by the Canadian Institutes of Health Research, the British Columbia Ministry of Health and the British Columbia Centre for Disease Control, Alberta Health and Wellness, the Ontario Agency for Health Protection and Promotion, the Ontario Ministry of Health and Long Term Care, the Ministère de la santé et des services sociaux du Québec, the Institut national de santé publique du Québec and the Fonds de la recherche en santé du Québec (FRSQ). Although agencies of the investigators provided infrastructure in support of the reported studies, the funders did not have a role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.


Story Source:

The above story is based on materials provided by Public Library of Science. Note: Materials may be edited for content and length.


Journal References:

  1. Skowronski DM, De Serres G, Crowcroft NS, Janjua NZ, Boulianne N, et al. Association between the 2008-09 Seasonal Influenza Vaccine and Pandemic H1N1 Illness during Spring-Summer 2009: Four Observational Studies from Canada. PLoS Medicine, 2010; 7(4): e1000258 DOI: 10.1371/journal.pmed.1000258
  2. Viboud C, Simonsen L. Does Seasonal Influenza Vaccination Increase the Risk of Illness with the2009 A/H1N1 Pandemic Virus? PLoS Medicine, 2010; 7(4): e1000259 DOI: 10.1371/journal.pmed.1000259

Cite This Page:

Public Library of Science. "Did seasonal flu vaccination increase the risk of infection with pandemic H1N1 flu?." ScienceDaily. ScienceDaily, 7 April 2010. <www.sciencedaily.com/releases/2010/04/100406172635.htm>.
Public Library of Science. (2010, April 7). Did seasonal flu vaccination increase the risk of infection with pandemic H1N1 flu?. ScienceDaily. Retrieved September 19, 2014 from www.sciencedaily.com/releases/2010/04/100406172635.htm
Public Library of Science. "Did seasonal flu vaccination increase the risk of infection with pandemic H1N1 flu?." ScienceDaily. www.sciencedaily.com/releases/2010/04/100406172635.htm (accessed September 19, 2014).

Share This



More Health & Medicine News

Friday, September 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

The Cost of Ebola

The Cost of Ebola

Reuters - Business Video Online (Sep. 18, 2014) — As Sierra Leone prepares for a three-day "lockdown" in its latest bid to stem the spread of Ebola, Ciara Lee looks at the financial implications of fighting the largest ever outbreak of the disease. Video provided by Reuters
Powered by NewsLook.com
What HealthKit Bug Means For Your iOS Fitness Apps

What HealthKit Bug Means For Your iOS Fitness Apps

Newsy (Sep. 18, 2014) — Apple has delayed the launch of the HealthKit app platform, citing a bug. Video provided by Newsy
Powered by NewsLook.com
U.S. Food Makers Surpass Calorie-Cutting Pledge

U.S. Food Makers Surpass Calorie-Cutting Pledge

Newsy (Sep. 18, 2014) — Sixteen large food and beverage companies in the United States that committed to cut calories in their products far surpassed their target. Video provided by Newsy
Powered by NewsLook.com
Residents Vaccinated as Haiti Fights Cholera Epidemic

Residents Vaccinated as Haiti Fights Cholera Epidemic

AFP (Sep. 18, 2014) — Haitians receive the second dose of the vaccine against cholera as part of the UN's vaccination campaign. Duration: 00:34 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins