No 39 - 2015
Influenza vaccination 2015/2016
Influenza vaccination 2015/2016
October 1 marks the beginning of the 2015/2016 influenza season and therefore also the launch of the free influenza vaccination offer to select population groups.
In Europe, the 2014/15 influenza season was characterised by the fact that the influenza A-H3N2 virus that dominated the season had changed with respect to the H3N2 virus component in the vaccine. Therefore, protection provided by the vaccine against this influenza virus was limited, which contributed to the considerable excess mortality observed in several European countries.
In Denmark, however, the influenza activity only increased towards the end of February. Therefore, the season was rather short and the consequences not as comprehensive as in many other European countries. A total of 202 patients were recorded as having received intensive care at a hospital; and in the course of the winter period, approx. 700 more deaths than expected were recorded that were probably attributable to influenza.
A total of 78% of the intensive care patients had an underlying condition or were 65 years old or more, and only 38% of these critically ill intensive care patients had received influenza vaccination. This underlines the importance of increasing the influenza vaccination coverage among risk groups and persons aged 65 years and older.
The WHO's objective is a 75% coverage in this age group; in 2014/2015, however, coverage in Denmark only reached 46%. This year, the vaccine contains antigens from 2 new influenza viruses, which are believed to match the influenza viruses better than the ones which were in circulation last year.
Free influenza vaccination
In accordance with Executive Order of 8 September 2015 on free influenza vaccination to select population groups, the following persons residing in Denmark are entitled to free influenza vaccination:
- Persons who at the time of their vaccination have reached the age of 65 years
- Early retirement pensioners
- Chronically ill persons who suffer from the following conditions, upon medical assessment:
- Chronic pulmonary conditions
- Cardiovascular diseases (barring high blood pressure with no concurrent conditions)
- Diabetes 1 or 2
- Congenital or acquired immunodeficiency
- Patients whose respiration is affected due to muscular weakness
- Chronic liver or kidney failure
- Persons with other chronic diseases which, according to the physician’s assessment, pose a serious health risk in conjunction with influenza
- Severely obese persons (recommended BMI > 40) upon medical assessment
- Persons with other serious diseases that, according to the doctor’s assessment, pose a serious health risk in conjunction with influenza.
- Pregnant women in their 2nd or 3rd trimester
- Household contacts to severely immunosuppressed patients (congenital or acquired immune deficiency) upon medical assessment
The offer of free vaccination applies in the period from 1 October to the end of the year. For pregnant women in their 2nd and 3rd trimesters and for immunosuppressed persons and their household contacts, the period is extended until the end of February 2016.
The Danish Health and Medicines Authority has prepared a guideline for physicians on free influenza vaccination.
This year, the Danish Health and Medicines Authority will run a campaign to inform risk groups of influenza vaccination. In August, posters and other material were sent to GPs, pharmacies and head midwifes. Extra posters and visiting cards on influenza vaccination may be ordered at Schultz Distribution on phone: 7026 2636. Furthermore, information letters targeting patients at risk and the remaining materials are available for download (in Danish language) at the following website: www.beskytdigmodinfluenza.dk, under the portal targeting municipalities and healthcare workers. Additionally, the campaign consists of TV ads on national Danish TV and in pharmacies in weeks 39, 40 and 41, adds in weekly magazines and on relevant websites and a broad press campaign targeting national as well as local media.
This year two vaccines were procured (Fluarix and Vaxigrip) from two manufacturers. Both vaccines contain components of inactivated influenza virus, and they are considered equal with respect to protection against influenza. None of the vaccines contain thiomersal or any adjuvants. Both vaccines may contain trace amounts of eggs/chicken protein, formaldehyde and gentamicin. For more detailed information on the individual products and "Questions & Answers", please see the SSI's website.
Influenza vaccines in the 2015/2016 season
The composition of the vaccines was based on the WHO's recommendations and the vaccines contain antigens from three seasonal influenza viruses that are in circulation globally: Two of the virus components have been changed with respect to last year: The following components are included:
- A/California/7/2009 (H1N1)pdm09-like virus
- A/Switzerland/9715293/2013 (H3N2)-like virus (NEW VIRUS)
- B/Phuket/3073/2013-like virus (the Yamagata line) (NEW VIRUS).
Children above the age of 6 months with a risk of running a serious influenza course should be vaccinated. In the majority of cases, such children are monitored by a paediatric clinic, but they may also receive free vaccination at a specialist or at a vaccination clinic.
Children aged from 6 months through 8 years and who have not previously been vaccinated against influenza should receive two vaccinations at a minimum interval of 4 week. Children aged 6 through 35 months are vaccinated using only half the vaccine dose.
It may be relevant to vaccinate household contacts and other persons who come into close contact with children belonging to the risk groups, including children below 6 months of age.
Pregnancy and breast-feeding
Pregnant women are at increased risk of suffering serious complications from influenza infection compared with non-pregnant women, and this is particularly evident for influenza A(H1N1)pdm09, which has been in circulation since 2009.
The Danish Health and Medicines Authority therefore recommends influenza vaccination of all pregnant women in their 2nd and 3rd trimesters. Pregnant women in their first trimester are also vaccinated, provided that they belong to a risk group. Many years of experience with vaccination of pregnant women globally have demonstrated that influenza vaccination during pregnancy is safe for the child and not associated with an increased risk of adverse reactions for the pregnant woman. Influenza vaccination of pregnant women may also protect the child in the first months of life as antibodies are transferred from mother to child. The influenza vaccine may also be given during the period of breastfeeding.
Patients with multiple sclerosis are at risk of having new attacks if their disease is complicated by influenza. Risk of new attacks as a result of vaccination has not been observed.
Like all other immunocompromised persons, HIV-infected persons are at an increased risk of running a serious influenza course, and all HIV-infectees are therefore encouraged to receive free influenza vaccination with their GP.
Degree of protection
Immunity achieved through vaccination with inactivated influenza virus is generally effective 2-3 weeks after vaccination and the effect generally lasts 6-12 months. The degree of protection depends mainly on the correlation between the type of virus in circulation and the virus strains in the vaccine. In young, healthy persons, vaccination prevents up to 70-90% of influenza cases. In elderly persons, protection against ordinary influenza illness is somewhat lower. Protection against serious complications, hospital admissions and death in the elderly is up to 60%.
Adverse reactions and contraindications
Fever, malaise, rigours and tiredness are common vaccination reactions. They typically recede after 1-2 days. The inactivated influenza vaccines do not cause influenza illness.
Persons who are hypersensitive to chicken eggs/chicken protein or other vaccine ingredients and who previously experienced an anaphylactic reaction should not be vaccinated. Allergy to formaldehyde will most frequently manifest itself as contact dermatitis in connection with which patch tests may be positive, which, however, does not constitute a contraindication. To avoid such reaction, the vaccine may be administered intramuscularly.
Neuroaminidase inhibitors may be used prophylactically in persons who are unvaccinated due to contraindications and in unvaccinated contacts.
Statens Serum Institut's influenza surveillance will be in place as from Week 40. INFLUENZA-NEWS including weekly updates on national Danish as well as international influenza incidence will start being published regularly once the initial signs of influenza activity have been observed.
(T.G. Krause, L.K. Knudsen, Department of Infectious Disease Epidemiology)
23 September 2015