High effectiveness of pandemic influenza A H1N1 vaccination in healthcare workers from a Portuguese hospitalReport as inadecuate

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International Archives of Occupational and Environmental Health

, Volume 85, Issue 7, pp 747–752

First Online: 02 November 2011Received: 26 March 2011Accepted: 11 October 2011


ObjectivesVaccination of healthcare workers HCWs was made a high priority during the phase six pandemic of the novel influenza A H1N1 pH1N1 virus. We surveyed adherence to pH1N1 vaccination and the incidence of pH1N1 infection between vaccinated and unvaccinated HCWs.

MethodsEmployees at the S. João Hospital in Porto, Portugal, were offered pH1N1 vaccinations free of charge. Pandemrix was the vaccine administered. As part of the pandemic plan, employees with influenza-like symptoms ILS were called upon to take an RT-PCR H1N1 test. If the test results were positive, they had to stay off work for at least 7 days. Sociodemographic data, vaccination status, contact with infectious patients, ILS and pH1N1 test results were documented in a standardised manner.

ResultsThe survey population comprised 5,592 employees. The vaccination rate was 30.8% n = 1,720 for pH1N1 and 50.4% n = 2,819 for the 2009-2010 seasonal trivalent inactivated influenza vaccine TIV. One mild anaphylactic reaction occurred after pH1N1 vaccination. Minor local side effects occurred more often after pH1N1 vaccination than after 2009-2010 seasonal TIV 38.0% vs. 12.3%. Pandemic H1N1 infection was diagnosed in 97 HCWs 1.7%. Compared to employees with no regular patient contact, nurses 2.8% had the highest risk of pH1N1 infection adjusted OR 3.8; 95% CI 1.2–6.8. Vaccination reduced the pH1N1 infection risk OR 0.12; 95% CI 0.05–0.29. Vaccine effectiveness was 90.4% 95% CI 73.5–97.3%.

ConclusionVaccination reduced the pH1N1 infection risk considerably. The pandemic plan to contain the pH1N1 infection was successful. Nurses had the highest risk of pH1N1 infection and are therefore a target group for vaccination measures.

KeywordsPandemic influenza A H1N1 Healthcare workers Vaccination AbbreviationspH1N1Pandemic influenza A H1N1

ILSInfluenza-like symptoms

TIVTrivalent inactivated influenza vaccine

HCWsHealthcare workers

OROdds ratio

RT-PCRReal-time reverse transcriptase–polymerase chain reaction

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Author: José Torres Costa - Rui Silva - Margarida Tavares - Albert Nienhaus

Source: https://link.springer.com/

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