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
Influenza vaccination for winter 2010/11
Influenza vaccination for winter 2010/11
Pregnant women in
seasonal flu at risk
groups (excluding
immunocompromised)
Pregnant women
not in at risk
group
If previously
received
monovalent H1N1
vaccine
One dose
trivalent
seasonal
influenza
vaccine
No vaccine
required
Pregnant women who
are immunocompromised
If NOT
previously
received
monovalent
H1N1
vaccine
If NOT
previously
received
monovalent
H1N1
vaccine
If previously
received
monovalent H1N1
vaccine
One dose
trivalent
seasonal
influenza
vaccine
One dose
monovalent
H1N1
vaccine
One dose
trivalent
seasonal
influenza
vaccine
Four Weeks
later one dose
trivalent
seasonal flu
vaccine
http://www.dh.gov.uk/prod_consum_dh/groups/dh_digitalassets/@dh/@en/documents/digitalasset/dh_119559.pdf