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Seroconversion and asymptomatic infections during oseltamivir prophylaxis against Influenza A H1N1 2009.
BMC Infect Dis 2010; 10:164BI

Abstract

BACKGROUND

Anti-viral prophylaxis is used to prevent the transmission of influenza. We studied serological confirmation of 2009 Influenza A (H1N1) infections during oseltamivir prophylaxis and after cessation of prophylaxis.

METHODS

Between 22 Jun and 16 Jul 09, we performed a cohort study in 3 outbreaks in the Singapore military where post-exposure oseltamivir ring chemoprophylaxis (75 mg daily for 10 days) was administered. The entire cohort was screened by RT-PCR (with HA gene primers) using nasopharyngeal swabs three times a week. Three blood samples were taken for haemagglutination inhibition testing--at the start of outbreak, 2 weeks after completion of 10 day oseltamivir prophylaxis, and 3 weeks after the pandemic's peak in Singapore. Questionnaires were also administered to collect clinical symptoms.

RESULTS

237 personnel were included for analysis. The overall infection rate of 2009 Influenza A (H1N1) during the three outbreaks was 11.4% (27/237). This included 11 index cases and 16 personnel (7.1%) who developed four-fold or higher rise in antibody titres during oseltamivir prophylaxis. Of these 16 personnel, 8 (3.5%) were symptomatic while the remaining 8 personnel (3.5%) were asymptomatic and tested negative on PCR. Post-cessation of prophylaxis, an additional 23 (12.1%) seroconverted. There was no significant difference in mean fold-rise in GMT between those who seroconverted during and post-prophylaxis (11.3 vs 11.7, p = 0.888). No allergic, neuropsychiatric or other severe side-effects were noted.

CONCLUSIONS

Post-exposure oseltamivir prophylaxis reduced the rate of infection during outbreaks, and did not substantially increase subsequent infection rates upon cessation. Asymptomatic infections occur during prophylaxis, which may confer protection against future infection. Post-exposure prophylaxis is effective as a measure in mitigating pandemic influenza outbreaks.

Authors+Show Affiliations

Biodefence Centre, Ministry of Defence, Transit Road, Singapore 778910, Singapore. vernonljm@hotmail.comNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

20537158

Citation

Lee, Vernon J., et al. "Seroconversion and Asymptomatic Infections During Oseltamivir Prophylaxis Against Influenza a H1N1 2009." BMC Infectious Diseases, vol. 10, 2010, p. 164.
Lee VJ, Yap J, Tay JK, et al. Seroconversion and asymptomatic infections during oseltamivir prophylaxis against Influenza A H1N1 2009. BMC Infect Dis. 2010;10:164.
Lee, V. J., Yap, J., Tay, J. K., Barr, I., Gao, Q., Ho, H. J., ... Chen, M. I. (2010). Seroconversion and asymptomatic infections during oseltamivir prophylaxis against Influenza A H1N1 2009. BMC Infectious Diseases, 10, p. 164. doi:10.1186/1471-2334-10-164.
Lee VJ, et al. Seroconversion and Asymptomatic Infections During Oseltamivir Prophylaxis Against Influenza a H1N1 2009. BMC Infect Dis. 2010 Jun 10;10:164. PubMed PMID: 20537158.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Seroconversion and asymptomatic infections during oseltamivir prophylaxis against Influenza A H1N1 2009. AU - Lee,Vernon J, AU - Yap,Jonathan, AU - Tay,Joshua K, AU - Barr,Ian, AU - Gao,Qiuhan, AU - Ho,Hanley J, AU - Tan,Boon Huan, AU - Kelly,Paul M, AU - Tambyah,Paul A, AU - Kelso,Anne, AU - Chen,Mark I, Y1 - 2010/06/10/ PY - 2010/03/23/received PY - 2010/06/10/accepted PY - 2010/6/12/entrez PY - 2010/6/12/pubmed PY - 2010/9/25/medline SP - 164 EP - 164 JF - BMC infectious diseases JO - BMC Infect. Dis. VL - 10 N2 - BACKGROUND: Anti-viral prophylaxis is used to prevent the transmission of influenza. We studied serological confirmation of 2009 Influenza A (H1N1) infections during oseltamivir prophylaxis and after cessation of prophylaxis. METHODS: Between 22 Jun and 16 Jul 09, we performed a cohort study in 3 outbreaks in the Singapore military where post-exposure oseltamivir ring chemoprophylaxis (75 mg daily for 10 days) was administered. The entire cohort was screened by RT-PCR (with HA gene primers) using nasopharyngeal swabs three times a week. Three blood samples were taken for haemagglutination inhibition testing--at the start of outbreak, 2 weeks after completion of 10 day oseltamivir prophylaxis, and 3 weeks after the pandemic's peak in Singapore. Questionnaires were also administered to collect clinical symptoms. RESULTS: 237 personnel were included for analysis. The overall infection rate of 2009 Influenza A (H1N1) during the three outbreaks was 11.4% (27/237). This included 11 index cases and 16 personnel (7.1%) who developed four-fold or higher rise in antibody titres during oseltamivir prophylaxis. Of these 16 personnel, 8 (3.5%) were symptomatic while the remaining 8 personnel (3.5%) were asymptomatic and tested negative on PCR. Post-cessation of prophylaxis, an additional 23 (12.1%) seroconverted. There was no significant difference in mean fold-rise in GMT between those who seroconverted during and post-prophylaxis (11.3 vs 11.7, p = 0.888). No allergic, neuropsychiatric or other severe side-effects were noted. CONCLUSIONS: Post-exposure oseltamivir prophylaxis reduced the rate of infection during outbreaks, and did not substantially increase subsequent infection rates upon cessation. Asymptomatic infections occur during prophylaxis, which may confer protection against future infection. Post-exposure prophylaxis is effective as a measure in mitigating pandemic influenza outbreaks. SN - 1471-2334 UR - https://www.unboundmedicine.com/medline/citation/20537158/Seroconversion_and_asymptomatic_infections_during_oseltamivir_prophylaxis_against_Influenza_A_H1N1_2009_ L2 - https://bmcinfectdis.biomedcentral.com/articles/10.1186/1471-2334-10-164 DB - PRIME DP - Unbound Medicine ER -