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New Therapies for Influenza

Key points

  • Pregnant women are a group at high risk of influenza related morbidity and mortality.
  • Approval for the use of intravenous Zanamivir ('Dectova') has recently been granted in the EU.
  • Exposure to intravenous Zanamivir is highly likely for pregnant women with complicated influenza.

Surveillance period

1st Jan 2020 – 31st August 2023


Pregnant women are recognised as a group at increased risk of influenza related morbidity and mortality[1][2][3] and higher rates of influenza-related morbidity requiring hospitalisation during seasonal epidemics[4][5][6]. Due to limited treatment options, antiviral drug resistance remains a public health concern, and alternative treatments are needed in case of widespread resistance. Approval for the use of intravenous Zanamivir has recently been granted in the EU. The proposed indication is for the treatment of complicated influenza virus A and B infection in adults and children aged from six months, with progressive and possibly life-threatening influenza infections, where there are limited therapeutic options. Given that pregnant women are a group at high risk, exposure to intravenous Zanamivir in pregnancy is likely. This study, which will run alongside a newly-developed PharmacoVigilance in Pregnancy (PVIP) system, will aim to evaluate the safety of the new approved drug, intravenous Zanamivir, in pregnant women with complicated influenza.


To use the UK Obstetric Surveillance System (UKOSS) to evaluate pregnancy, birth and infant outcomes among women exposed to intravenous Zanamivir at any time during pregnancy.

Research questions

  • What is the incidence of pregnant women admitted to hospital for complicated influenza and exposed to intravenous Zanamivir?
  • What are the outcomes of intravenous Zanamivir treatment for influenza in pregnancy for both mother and infant?

Case definition

Any pregnant woman admitted to hospital with influenza who receives at least one dose of intravenous Zanamivir.

Please note: UKOSS will be used to merely identify cases and reporters will only be required to complete a very short questionnaire. Detailed data collection will be undertaken, with consent, using the PVIP system.


Glaxo Smith Kline via OXON Epidemiology

Ethics committee approval

This study has been approved by the North London REC1 (Ref. Number: 10/H0717/20).

Lead investigators

Marian Knight, NPEU; Nawab Qizilibash, OXON Epidemiology

Sample Data Collection Form

UKOSS New Therapies for Influenza DCF


  1. ^ Harris JW. Influenza occurring in pregnant women. JAMA. 1919; 72:978-80.
  2. ^ Freeman DW, Barno A. Deaths from Asian influenza associated with pregnancy. Am J Obstet Gynecol. 1959; 78:1172-5.
  3. ^ Siston AM et al. Pandemic 2009 influenza A (H1N1) virus illness among pregnant women in the United States. JAMA. 2010; 303:1517-25.
  4. ^ Dodds L et al. Impact of influenza exposure on rates of hospital admissions and physician visits because of respiratory illness among pregnant women. Canadian Medical Association Journal. 2007; 176:163-8.
  5. ^ Neuzil KM, Reed GW, Mitchel EF, Simonsen L and Griffin MR. Impact of influenza on acute cardiopulmonary hospitalizations in pregnant women. Am J Epidemiol. 1998; 148:1094-102.
  6. ^ Mertz D et al. Populations at risk for severe or complicated influenza illness: systematic review and meta-analysis. BMJ. 2013; 647: f5061.

Updated: Monday, 16 October 2023 11:37 (v11)