Serious consequences of influenza can be avoided by vaccination

In healthy young persons a short-term influenza respiratory disease caused by the influenza virus may cure itself. The disease itself lasts 1-5 days but full recovery can take 1-2 weeks (Cox & Fukuda, 1998). The most efficient way to prevent influenza is by vaccination. Influenza vaccination has the objective to prevent influenza risk and thereby serious illness, complications and death. There are still chances, however, that people who are vaccinated will get influenza but the chance of complications and mortality is lower (Wang et al., 2007).

Vaccination is recommended for risk groups

Although complications from flu can occur in anyone, they are far more common among the high-risk groups. A survey by ECDC in 2006 of EU Member States and associated EEA countries found that countries were recommending annual vaccination to the two largest groups highlighted by the WHO:

• The elderly
• People with chronic medical conditions, such as lung and heart disease, and people whose immune systems are weak

There are different approaches in the various European countries regarding the groups to be vaccinated. As for the elderly, the specific age range for people in this group may vary from one country to another. A majority of countries recommend vaccination for people aged 65 and over, however some recommend it for people aged 60 and over or even 50 and over. The WHA , which includes all EU/EEA countries, has supported a proposal in 2003 that there should be targets for uptake of influenza vaccination in the elderly of 50% by 2006 and 75% by 2010. Currently, most EU/EEA countries fall short of this standard.

Many countries especially emphasise the importance of annual immunisation of people living in residential care settings for the elderly and disabled. The majority of countries in Europe recommend that all health care staff should be immunised against influenza. In this way staff that are more likely to be exposed through their work are protected, as well as the patients they are dealing with. Few EU countries recommend immunization of children or offering vaccines to pregnant women. An expert panel convened by ECDC considered there was as yet insufficient evidence on the burden of infection in children to take any view for or against immunization.

Recommendations on influenza vaccinatioin adopted by the European Commission

The European Commission has adopted recommendations regarding seasonal influenza vaccination. These recommendations include improving vaccination coverage rates in order to reach, as early as possible, however, no later than by the winter season 2014/2015, vaccination coverage rate of 75% in all at risk groups. These are older age groups (65 years and older) and people with underlying medical conditions. Member States should organise annual uptake surveys in all at risk groups and foster education, training, and information exchange on seasonal influenza (Commission of the European Communities, 2009).

Influenza vaccination is effective and cost saving

Influenza vaccination reduces the morbidity and mortality of influenza. The chance to get influenza decreases with 70-80% in adults younger than 65 years. In the elderly it reduces the risk somewhat less, namely 30-70%, and it reduces the risk of complications with 20-50 % (NHG & LVG, 2008). A serial cohort study has shown that among elderly people living in the community, vaccination against influenza was associated with less frequent hospitalizations for complications of influenza, with fewer deaths during the influenza season, and with direct savings in health care costs. These findings were consistent over three consecutive seasons among cohorts of more than 25,000 elderly men and women (Nichol et al., 1994).

Vaccination of people outside the risk groups

It has been investigated whether influenza vaccination of individuals outside the risk groups is cost effective. Influenza vaccination in healthy individuals aged 50 to 64 years has been estimated to be cost effective (Turner et al., 2006). Other cost-effectiveness analyses were focusing on all healthy adults younger than 65 years. In this total group, the conclusion was that vaccination is cost effective and cost saving. Also vaccination of health personnel has been shown to be cost effective and cost saving (Burls et al., 2006).

How effective is influenza vaccination in the elderly?

There is no doubt that influenza vaccines are effective in preventing influenza infection in healthy adults (Demicheli et al., 2004). There is however a debate about how effective the influenza vaccine in elderly really is. Some scientists claim that there is no sufficient evidence that shows that vaccination substantially reduces the risk of influenza-related mortality among elderly people. This claim is based on the following (Simonsen et al., 2007):

• There is no randomised clinical trial (placebo-controlled) data conclusively showing a benefit in those aged 70 years or more, the age-group that accounts for nearly all influenza-related deaths.
• The vaccine effectiveness declines sharply after age 70 years (Govaert et al., 1994). Immunologists have shown that immune responses to novel antigens are seriously impaired in the oldest age-groups (Vallejo, 2007). Placebo-controlled RCTs find that antibody responses to influenza vaccine in elderly people are only about one-quarter to one-half as strong as responses found in younger adults (Goodwin et al., 2005). Some studies have shown lower efficacy among the elderly, for example, a vaccine effectiveness of 29% for prevention of hospital admission with laboratory-confirmed influenza (Falsey et al., 2005).

Though doubting the effectiveness of the vaccine in elderly Simonsen et al. recommend that this group should continue to be vaccinated because even a partly effective vaccine is better than no vaccine at all (Simonsen et al., 2007).

Low coverage of influenza vaccination in the elderly in many European countries

The countries of the European Region of WHO, including all EU Member States, have committed themselves to the goal of attaining vaccination coverage of the elderly population of at least 50% by 2006 and 75% by 2010. In 2007 the Netherlands is the only country to reach the WHA 2010 target of 75% coverage in the elderly with 77% coverage. See Increase in influenza vaccination rate for the population aged 65 and above in selected countries between the years 2001 and 2007. The United Kingdom reached a percentage just below this target at 74%. There is low vaccination coverage especially in the new Member States of the EU (Mereckiene et al., 2008). For other risk groups than older people, it is difficult to compare vaccination rates among countries (Kroneman et al., 2003).

See also: Trends in influenza vaccination rate for the population aged 65 and above in selected countries, 2000-2007.

Prevention or treatment of influenza by anti-virals

Uncomplicated influenza is not treated with antibiotics. These are only given when there is evidence of a secondary bacterial infection. Recently, new antiviral drugs for prevention and treatment of influenza have been developed. The M2 ion channel blockers or adamantanes (amantadine and rimantadine) have been available since the sixties of the previous century, however, its use is limited because of rapid development of resistance, serious adverse effects, and being only active against influenza A viruses. The newer neuraminidase inhibitor drugs oseltamivir and zanamivir are active against influenza viruses type A and B, and development of resistance is slow. Both types of drug reduce the severity of illness and shorten the disease duration by half to one day. These drugs should be taken within 48 hours after the onset of first symptoms (Cooper et al., 2003a). These antivirals are prescribed only in special cases, e.g. risk patients with influenza. Vaccination remains the best way to prevent influenza. Most of currently circulating seasonal A(H1N1) viruses are resistant against oseltamivir but sensitive for zanamivir and the adamantanes, whilst most of currently circulating seasonal A(H3N2) viruses are resistant against the adamantanes but sensitive for the neuraminidase inhibitors.

Tests on viruses obtained from patients in Mexico and the United States have indicated that the 2009 novel influenza virus A(H1N1) is sensitive to neuraminidase inhibitors, but that the virus is resistant to the other class of drugs, the adamantanes (WHO, 2009g).

Prevention by individual protection and hygienic measures

The WHO has drawn up advice on how to protect oneself from Influenza A(H1N1). For example, cover the nose and mouth with disposable tissue when coughing; dispose of used tissues immediately after use, etc. For more information see: “Influenza A(H1N1) How to protect yourself and others”.

General hygiene measures are applied to determine contamination or spread of infections with influenza prevention. In particular, washing hands with soap and water is effective in the reduction of live virus particles to virus undetectable in culture (Grayson et al., 2009). The use of masks, as in Asian countries, may also help to limit spread (MacIntyre et al., 2009).

Four pandemic influenza A (H1N1) 2009 vaccines are soon available on the European market. For more details see the ECDC website.