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Update on influenza H1N1 (2009) for providers of maternity services The end of the influenza pandemic that began in 2009, was announced by the World Health Organisation on 10th August 2010. This reflected the falling numbers of cases reported from most countries of the world.

Influenza H1N1 (2009) is no longer causing a pandemic, but it remains common among circulating flu viruses.

Large numbers of infections with this virus are still being reported from Southern India, parts of Pakistan and parts of New Zealand. Influenza H1N1 (2009) is now considered a common seasonal flu virus in parts of the Southern Hemisphere where seasonal flu is now active, and is starting to be detected in more northern regions as autumn begins. Sporadic cases are still being diagnosed in Mexico and in Europe, including in the United Kingdom. Although there is no indication of another pandemic wave, the Joint Committee on Vaccination and Immunisation (JCVI) is currently advising that H1N1 is likely to be the predominant influenza strain circulating in the 2010/11 winter season.

Pregnant women are still a high-risk group for severe influenza infection caused by the H1N1 (2009) virus

In the coming influenza season, pregnant women are likely to be exposed to this virus, and those who did not develop immunity in the recent pandemic may become ill, with a risk of severe or complicated disease. Pregnant women appear to be at increased risk of complications, including death, from H1N1 (2009) influenza infection. The greatest risk is of severe chest infection, due to the flu itself, or to secondary bacterial infection - commonest in the second and third trimesters of pregnancy. Increased severity from influenza H1N1 (2009) infection in pregnancy is associated with preexisting asthma, maternal smoking and obesity. Pregnant women admitted to hospital with H1N1 (2009) infection are (three times) more likely to deliver pre-term. However, pregnant women should also avoid the risk of severe feverish illness at any stage of pregnancy. It is important to remember that flu can cause other types of illness at any stage, including diarrhoea and/or vomiting, muscle and joint inflammation and, rarely, meningitis.

Prevention and treatment of flu in pregnancy: 1. Vaccination As in every year, the seasonal influenza vaccine for 2010-2011 contains three different flu virus strains. One of these generates immunity to the H1N1 (2009) flu virus. Vaccination for all at-risk people is available through GP surgeries.

All healthcare professionals working in maternity services should be actively encouraged to accept vaccination against seasonal flu, offered through their employer’s Occupational Health Service. This will protect both staff from infection and the pregnant women from exposure to infected staff.

As usual, pregnant women in high-risk groups for severe and complicated flu should be offered this vaccine as soon as it becomes available. Also all pregnant women who have not previously received the pandemic flu vaccine (when it became available during the pandemic of 2009-2010) should also be offered one dose of the seasonal flu vaccine, to protect them from infection with the influenza H1N1 (2009) virus. The exception to this is those pregnant women who are immunocompromised. In this situation, if they have not previously received monovalent H1N1 vaccine then one dose of monovalent vaccine should be offered followed by one dose of seasonal vaccine four weeks later.

It is safe to give seasonal flu vaccine at any stage of pregnancy (in some other Western countries, seasonal vaccines have been given to all pregnant women for several years). Vaccination of pregnant women may also provide protection for the first 4-6 months of life of the infant, through passive immunity.

2. Antiviral treatment for flu While vaccination is considered the first line of defence against flu, antiviral medicines are effective in treating flu, and experience has shown them to be safe at all stages of pregnancy. The European Medicines Agency has recommended that either oral oseltamivir (Tamiflu) capsules or inhaled zanamivir (Relenza) can be taken by pregnant women. In England, pregnant women and their healthcare advisors usually chose to use inhaled zanamivir during the recent pandemic, except for women with asthma or other lung disorder likely to cause bronchospasm (asthma-like symptoms).

GPs’ contracts allow them to prescribe antiviral medicines according to the guidance provided by the National Institute for Health and Clinical Excellence (NICE). This

includes people in high-risk groups for severe and complicated influenza, but only when a seasonal influenza virus is circulating in the community (the Chief Medical Officer informs all GPs when this situation arises).

Pregnant women who are in the high-risk groups for severe or complicated flu can be prescribed antiviral medicines. However, GPs cannot currently prescribe antivirals for pregnant women with NO OTHER MARKER of being high-risk. Hospital doctors can prescribe antiviral medicines at any time, based on a clinical or laboratory diagnosis of flu.

If a pregnant woman has an influenza-like illness during a seasonal flu epidemic, it is likely to be due to influenza virus infection. A GP (or other appropriately trained healthcare worker) should refer her to a hospital maternity service for assessment and investigation of her illness. There should be a low threshold for hospital clinicians prescribing an antiviral medicine and this should be done before the results of tests are available if appropriate. This does not mean that the woman would need hospital admission. An outpatient or walk-in consultation may be sufficient. From 1 November 2010, the regulations will be changed so that the groups of 'at clinical risk' people who are eligible to receive the influenza treatments Tamiflu and Relenza prescribed by General Practitioners will be widened to include pregnant women.

It is important to note that, in keeping with the post-pandemic phase, H1N1 influenza infection may continue to occur sporadically, independent of seasonal flu epidemic periods.

Future arrangements The Advice will be up-dated on 1st November to clarify the arrangements regarding prescription of antiviral medicines for pregnant women.

This statement has been agreed by:

Department of Health Health Protection Agency Royal College of General Practitioners Royal College of Midwives Royal College of Obstetricians & Gynaecologists

14 th October 2010

Centre for Maternal and Child Enquiries

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