Respiratory infections common among vaccinated health care workers

PHILADELPHIA — Nearly one-quarter of vaccinated health care personnel developed symptomatic infections during the respiratory viral season, according to findings presented here.

Trish M. Perl, MD, MSc, of the department of medicine at Johns Hopkins Medical Institutions, Baltimore, and the ResPECT Study Team, said that despite high rates of morbidity due to viral respiratory disease among health care workers, the causes of acute respiratory illness remain undefined.

Trish M. Perl

The current study was conducted among 3,083 patients at 111 outpatient and emergency departments in seven centers in the US during the 2011-2012, 2012-2013 and 2013-2014 respiratory seasons. Perl said respiratory seasons ran for 12 weeks. The results include findings for 4,291 swabs obtained from study participants.

“Overall we have had increasing participation over the study years,” Perl said.

Clinicians swabbed symptomatic participants and froze the cultures at -80ºC. Participants filled out daily exposure forms and weekly symptom diaries. Clinicians then obtained two more random swabs during intervention and tested the samples for 13 viruses using the RT-PCR/ESI-MS (Abbott Molecular) assay.

“This is a pretty novel technology and we can identify emerging pathogens quickly,” Perl said.

Paired blood samples for influenza antibodies (>2-fold antibody increase) also were obtained, according to Perl.

Eighty-four percent of patients in the first study year had received influenza vaccination, compared with 83% in the second year.

“About 55% of the isolates we identified were influenza A or B,” Perl said. “The other largest piece of this pie was coronavirus, which occurred in 25% of the population.”

When the data were broken down by year, Perl highlighted a large coronavirus endemic situation during the first study year, which she suggested impacted the incidence rates. “In years 2 and 3, we saw much more influenza,” she said.

She added that rhinovirus was found in 9% of the population, metapneumovirus in 3%, parainfluenza in 1% and enterovirus in 1%. Adenovirus and respiratory syncytial virus isolates also were found.

Results indicated positive test results for eight pathogens among 56% of patients with asymptomatic swabs and 100% of those with symptomatic swabs.

“If you drill down a little further into the data, you can see that in emergency departments, 46% of health care workers were asymptomatic and 25% were symptomatic,” Perl said. “There were a lot more asymptomatic people in the ED and we wonder if they had symptoms and just didn’t report them.”

Perl also noted that younger health care workers were more likely to be asymptomatic. “Participants older than 60 years were much more likely to be symptomatic,” she said.

Perl concluded that acute respiratory infections are “common” at 22% during the studied respiratory disease seasons.

“Younger health care workers are more likely to be asymptomatic, and among acute respiratory infections in health care workers, we could identify viral causes in 30%,” she said. “We are currently testing them for other pathogens. Influenza and coronavirus remain the most commonly identified pathogens.”

Finally, Perl noted that influenza was found in sites where the vaccine was mandated. “We are looking to see whether these infections occurred because of vaccine failures or for other reasons,” she said. – by Rob Volansky

For more information:

Los J. Abstract 129. Presented at: IDWeek 2014. Oct. 8-12; Philadelphia.

Disclosure: Perl reports associations with Medimmune, Merck and Pfizer.