Influenza (or ‘flu’) is a highly infectious viral illness of the respiratory tract, with a usual incubation period of 1–3 days (Public Health England, 2013a). It can be spread by respiratory droplets, aerosols and direct contact with infected respiratory secretions (Lau et al, 2010).
Typical characteristics of the disease are the rapid onset of fever, chills, headache, myalgia and extreme fatigue. There are many other common symptoms, such as a dry cough, sore throat and congested nose. For most healthy people, influenza is an unpleasant but usually self-limiting disease, with recovery seen within 5–7 days (Heymann, 2008). The illness can be complicated by otitis media, bronchitis, secondary bacterial pneumonia, and more rarely by meningitis, encephalitis or meningoencephalitis, which could ultimately lead to death (Heymann, 2008; Hawker et al, 2012). Although influenza infection can happen all year round, most influenza infections in the UK occur in an 8–10 week period during the winter.
The influenza virus
There are three types of influenza virus: A, B and C. Influenza types A and B are responsible for most clinical illness. Influenza C virus causes relatively minor symptoms and is not included in influenza vaccines. Influenza A strains are subject to unpredictable changes to their surface proteins (haemagglutinin and neuraminidase). Where a small change occurs, this is known as antigenic drift, however, major changes in the surface proteins can occur, and is known as antigenic shift. Where this happens and a new sub-type of influenza A virus occurs, large outbreaks and pandemics may be seen because of little or no population-level immunity to the virus. Influenza B virus is subject to antigenic drift but with less frequent changes than influenza A. The burden of influenza B infection is mostly in children, with severity of disease similar to that of influenza A (Public Health England, 2013a).
The risk of serious illness from influenza is higher among children less than 6 months of age, adults over the age of 65, and those with chronic underlying health conditions such as respiratory or cardiac disease, chronic neurological conditions, or immunosuppression, and pregnant women (Pebody et al, 2010).
Effect of influenza infection in pregnancy and new born babies
Natural changes in the immune response of a woman during pregnancy, which is thought to happen in response to the fetus being semi-allogenic, can disrupt the production of a specific immune response to pathogens (World Health Organization (WHO), 2014). This can lead to an increased susceptibility to infectious diseases for the women and fetus, with the potential for severe outcomes (Jamieson et al, 2006). Once thought to be ‘immunosuppressed’, the pregnant woman actually undergoes an immunological transformation, where the immune system is necessary to promote and support the pregnancy and growing fetus. When this protection is breached, as in a viral infection, this security is weakened, and infection with other micro-organisms can then propagate and lead to outcomes such as secondary infections and preterm labour (Silasi et al, 2015).
Influenza infection in pregnancy increases the risk of miscarriage, premature birth and low birth weight (Pierce et al, 2011, Mendez-Figueroa et al, 2011). Maternal morbidity and mortality from influenza infection is higher in pregnant women compared with non-pregnant women (Pebody et al, 2010) and worsens if the woman has existing risk factors, such as diabetes (WHO, 2012). During the period 2009–2012, one in eleven maternal deaths in pregnancy in the UK was due to influenza (Knight et al, 2014).
In addition to maternal risks, infants born to women with a clinical diagnosis of influenza during pregnancy are more likely to be born prematurely or be small for gestational age (Omer et al, 2012), and are at twice the risk of subsequent fetal death (Håberg et al, 2013).
Influenza immunisation policy in the UK
Since the 1960s, annual influenza immunisation is recommended for those in clinical risk groups, with the aim of protecting those who are at a higher risk of influenza-associated morbidity and mortality (Public Health England, 2013a).
During the 2009/10 influenza A/H1N1 pandemic, pregnant women were more likely than the general population to suffer serious disease, be admitted to hospital, require intensive care treatment (Jamieson et al, 2009). Pregnant women were also eight times more likely to die from influenza than the non-pregnant population (Pebody et al, 2010). As a result, the Joint Committee on Vaccination and Immunisation (JCVI), the expert advisory body to all UK health departments, recommended that during the pandemic pregnant women should be immunised against influenza A/H1N1. In 2010, JCVI advised seasonal influenza vaccine should be routinely offered to pregnant women (Public Health England, 2013a).
Manufacture and availability of annual influenza vaccines
Due to the unpredictable changes of influenza viruses, global disease epidemiology is continually monitored by WHO, which, based on this surveillance data, makes recommendations for both the northern and southern hemispheres, regarding vaccine strain content for respective influenza seasons (WHO, 2017). Once production of influenza vaccines has started, usually around February each year for the northern hemisphere, vaccine strain content cannot be changed or amended.
Influenza does not usually reach a significant level in the UK before the middle of November; however, the influenza season may start early (Public Health England, 2013a). The optimum time for immunisation to start is as soon as the vaccine is available, usually in late September or early October. Women becoming pregnant during the influenza season should also be offered the vaccine. Protection acquired through immunisation is thought to last for at least one influenza season. Due to potential changes in the circulating strains of influenza from season to season, women pregnant in subsequent influenza seasons should be re-offered the vaccine.
Influenza vaccine safety and efficacy
There are two types of influenza vaccines available in the UK, inactivated (killed) and live (attenuated). Live attenuated vaccines are contraindicated during pregnancy as there is a theoretical risk that a live attenuated vaccine virus might cross the placental barrier and risk infecting the fetus (WHO, 2014). The live attenuated influenza nasal spray vaccine licensed in the UK is used exclusively in the childhood immunisation programme because of its greater efficacy and ease of administration.
Inactivated influenza vaccines can be given in any trimester of pregnancy. There is no evidence of increased risk of adverse outcome in vaccinated women (Tamma, 2009; Keller-Stanislawski et al, 2014; Regan, 2015).
Inactivated influenza vaccines are generally well tolerated, with common vaccine associated adverse events limited to pain, redness and swelling at the injection site, low grade pyrexia and myalgia. More serious adverse events, such as anaphylaxis, are very uncommon. There are very few contraindications to immunisation with inactivated influenza vaccines, but these include a previous anaphylactic reaction the vaccine or to one of its components (Public Health England, 2013a). An inactivated influenza vaccine can be given to pregnant women at the same time pertussis-containing vaccines.
The changing nature of influenza viruses can lead to influenza seasons in which strains that the vaccine protects against are not well matched against those circulating in the population. A meta-analysis by Osterholm et al (2012), which included studies when the influenza virus strains in the vaccine were not well matched with those in circulation, found an overall effectiveness against confirmed influenza of 59% (95% confidence interval 51–67%) in adults aged 18–65 years.
When given in pregnancy, inactivated influenza vaccine reduces the risk of infection, prematurity and low gestational weight (Omer et al, 2011) and provides the neonate with passive immunity to influenza in the first few months of life (Zaman et al, 2008; Benowitz et al, 2010; Eick et al, 2011; Poehling et al, 2011). The vaccine also prevents infection and hospitalisation among infants whose mothers were immunised in pregnancy (Dabrera et al, 2014).
The latest Mothers and Babies: Reducing Risk through Audits and Confidential Enquiries (MBRRACE) report for 2012–2014 showed that there was only a single maternal death attributed to indirect sepsis due to influenza. This is a significant reduction from 9 deaths during the period of 2011–2013, 13 deaths in 2010–2012 and 27 deaths in 2009–2011 (Knight et al, 2016). According to the report, this reduction in deaths due to influenza is the only statistically significant change in the rate of maternal death from specific indirect causes. This should not however lead to complacency among health professionals, as this reduction is more likely a reflection of lower levels of influenza activity in the past few years (Knight et al, 2016).
Influenza vaccine uptake in pregnancy in England
Estimating vaccine uptake in pregnancy is challenging, because women will become pregnant and deliver babies at various points during the influenza season, meaning that the denominator is subject to frequent changes. For this reason, it is important that general practices are made aware when a woman becomes pregnant and when she is no longer pregnant, whatever the reason. This will allow practices to identify eligible women and to report accurate data for national uptake monitoring purposes. Such communication will also help the practice to record vaccines administered in other locations, such as community pharmacies and maternity units.
Estimated uptake of influenza vaccine among pregnant women in England for the 2014/15 to 2016/17 influenza seasons is given in Table 1. This data shows that uptake of the influenza vaccine in pregnancy is sub-optimal, with less than half of women receiving the vaccine. There is also wide geographical variation in uptake of influenza vaccination, for example from 28.7% in NHS Hounslow Clinical Commissioning Group (CCG), to 65.2% in NHS Stockport CCG (Public Health England, 2017a).
| Year | % uptake |
|---|---|
| 2014–2015 | 44.1 |
| 2015–2016 | 45.1 |
| 2016–2017 | 44.9 |
Uptake of influenza vaccine contrasts with uptake of pertussis vaccine in pregnancy, which averaged 73.8% across January–March 2017 (Public Health England, 2017b). The difference in uptake may in part be due to the pertussis vaccine being available all year round and is only given from 16 weeks gestation rather than at any stage of pregnancy.
Implementing influenza immunisation in Stockport CCG
Stockport CCG has had consistently high uptake of the influenza vaccination, having the highest uptake for pregnant women for several years (Public Health England 2015; 2016b; 2017c). The CCG has adopted a system where the midwives (who are predominantly based in GP surgeries rather than in Sure Start children's centres) will vaccinate women in their care during the routine antenatal clinic. The prenatal pertussis vaccination programme is run in the same way, and has been in place since pregnant women were first identified as an at-risk group. This system is embedded in normal midwifery care, and is well established among the community midwifery team, as well as hospital-based midwives.
Maternal attitudes to immunisation
Pregnant women have expressed a strong preference to receive information about immunisations from their midwife, with 90.1% reporting the midwife to be their ideal source of information if being offered a vaccine in pregnancy (Campbell et al, 2015). Vaccination in pregnancy has also been found to be acceptable to women if it were to protect them against a disease that is potentially life-threatening for pregnant women, or to protect their baby against a life-threatening disease (Campbell et al, 2015). Despite these high levels of acceptability, many women still have reservations and seek reassurance from their midwife that vaccination is safe and necessary for them and their baby, especially where there is a general reluctance for taking any medications during pregnancy. Many factors affect a woman's likelihood of accepting the influenza vaccination: safety for baby, safety for themselves, awareness of disease, concerns about the disease, concerns for effects on fetal and maternal health, and a lack of knowledge of the vaccine's importance, whether the vaccine is recommended by the health care provider, or where it can be obtained (Fisher et al, 2011; Steelfisher et al, 2011). If women do not receive the appropriate advice, time to discuss their concerns, or information on the potential risks of influenza, it is safe to presume that they would be much less likely to take time out of their busy lives to arrange an appointment.
The role of the midwife
Midwives are in a trusted and influential position in their caring capacity for pregnant women. They are ideally situated to deliver education and advice to women, and play a positive role in encouraging women to accept the seasonal influenza vaccine, whether by administering the vaccine directly, or by signposting to GP surgeries or local pharmacies who are signed up to deliver the NHS programme. This fits with the Nursing and Midwifery Council (NMC) Code (2015a), which states that midwives have a professional requirement to prevent ill health. They may also be well placed to encourage other members of the family unit to accept the vaccine where eligible, for example when women have children aged 2 or 3 years old, or those offered the vaccine as part of the schools programme. The nasal spray influenza vaccine for healthy children does not only help to protect the child against influenza, but also offers indirect protection to others, including pregnant women, who may be particularly vulnerable to influenza, by limiting the spread of the virus within the family home and community.
In general, midwives have been found to be in agreement with the policy of vaccinating all pregnant women with the seasonal influenza vaccine, and see it as part of the midwives role to deliver advice and information regarding the vaccine (Ishola et al, 2013). However, when surveyed, they did not feel that delivering the vaccination should be undertaken as a midwifery responsibility, with 46% stating it should not be part of the role, and only 35% feeling it should be a routine role (Ishola et al, 2013). Reasons for this lack of enthusiasm included anxieties around workload, remuneration, training, safety and potential liabilities, and for those who had been actively vaccinating patients, that they were not adequately prepared for the responsibility.
Midwives have a responsibility to ensure they attend regular updates or complete online learning around immunisations (recommended minimum annually when administering to patients) (Health Protection Agency, 2005) to ensure up to date information around policy and recommendations, supporting safety of practice.
Health professionals themselves have poor uptake of the seasonal influenza vaccine, citing uncertainty about vaccine side effects, concern about vaccine safety and being too busy to attend the vaccine clinic (Chen et al, 2012). Those who are not in agreement with the immunisation programme should be cautious in their promotion of this—especially on social media—as they could be in breach of the NMC Code, which states: ‘Always practise in line with the best available evidence’ (NMC, 2015a). This means that midwives should not discuss anything that does not fall within their level of competence and should avoid making general comments that could be considered inaccurate (NMC, 2015b). Midwives should be encouraged to receive the influenza vaccination; not only to protect themselves and lessen the likelihood of sickness throughout the influenza season, but also to protect women and families, and to set a good example in practice.
Conclusion
Evidence shows that antenatal immunisation against influenza can protect women against infection and possible subsequent complications, including low birth weight, increased miscarriage rate, premature birth and maternal morbidity and mortality (Pebody et al, 2010). Studies have also shown that transplacental transfer of antibodies takes place, allowing protection for the unborn child that can last up to 6 months of age (Dabrera et al, 2014). Despite these well documented benefits, uptake of the vaccine remains low (44.9%) in England for 2016/17 season (Public Health England, 2017a). Health professionals, and midwives in particular, play a pivotal role in informing women about the benefits of immunisation, encouraging them to accept and access the vaccine, and providing evidence-based information where any questions or concerns are raised. Midwives are well positioned to provide a proactive public health role; however, as influenza vaccines have only been recommended for all pregnant women since 2010, and pertussis vaccines since 2012, immunisations of pregnant women may be a relatively new area of practice for a large number of midwives. Adequate training and support therefore need to be in place to support them in this new role, for delivery of not only the influenza and pertussis vaccines, but also the tuberculosis and hepatitis B immunisations for neonates where indicated.