No 39 - 2016

Influenza vaccination 2016/2017

October 1 marks the beginning of the 2016/2017 influenza season and therefore also the launch of the free influenza vaccination offer to select population groups.

In the 2015/2016 influenza season, a total of 5,152 patients had influenza established at a hospital. Hereof, 325 patients received intensive care and 75% of these had underlying disease or were older than 64 years. Based on data on excess mortality, it is assessed that approx. 1,000 persons died due to influenza.

In the 2015/2016 season, the influenza vaccine offered only limited protection against influenza infection. This was, among others, due to the fact that the influenza B type that was in circulation was not included in the vaccine. As usual, the next season’s vaccine contains antigens from three different influenza viruses, including two new influenza viruses which are believed to better match the influenza viruses that were in circulation in the past season.

Influenza vaccination remains the best available prevention against complications to influenza, complications which may lead to admission and death, particularly in risk groups. It is therefore worrying that the vaccination coverage among the elderly aged 65 years and above remains below 50%, which is far from the 75% coverage recommended by the WHO.

Free influenza vaccination

In accordance with Executive Order of 22 September 2016 on free influenza vaccination to select population groups (in Danish), 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 
  - Respiration affected due to muscular weakness 
  - Chronic liver or kidney failure 
  - Other chronic diseases which a physician assesses pose a serious health risk in conjunction with influenza
• Severe obesity (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 and 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 2016 to the end of the year. Nevertheless, vaccination remains free until the end of February 2017 for pregnant women who are past the first 12 weeks of gestation, and for persons with immunodeficiency and their household contacts.

The Danish Health Authority has prepared a guideline for physicians on free influenza vaccination (in Danish).

Information

This year, the Danish Health Authority runs the campaign “Time for influenza vaccination” (Danish: Tid til vaccination mod influenza) to inform risk groups about influenza vaccination. In the beginning of September, posters and other material were sent to GPs, pharmacies and leading midwives. Additional posters and cards about influenza vaccination can be ordered by phone at 7026 2636 and by e-mail at distribution@rosendahls.dk (state ”Influenza 2016” in the subject field). 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 page targeting municipalities and healthcare workers. Furthermore, the campaign comprises an ad campaign that is run in relevant media as from Week 39 and broad press efforts in national as well as local Danish media.

Delivery

To ensure that a sufficient number of vaccines are available, two vaccines (Influvac and Vaxigrip) from two different manufacturers were procured this year. Both vaccines contain components of inactivated influenza virus, and they are considered equal with respect to protection against influenza. None of the vaccines contains thiomersal or adjuvant. Both vaccines may contain trace amounts of eggs/chicken protein, formaldehyde, neomycin and gentamicin. For more detailed information on the individual products and "Questions & Answers", please see the SSI website.

Influenza vaccines in the 2016/2017 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 since last year. The following components are included:

• A/California/7/2009 (H1N1)pdm09-like virus
• A/Hong Kong/4801/2014 (H3N2)-like virus (NEW VIRUS)
• B/Brisbane/60/2008-like virus (the Victoria line) (NEW VIRUS).

Currently, only trivalent vaccines are used in Denmark. The WHO recommends that fourvalent vaccines contain two influenza B viruses. For the second B virus, the following is recommended: B/Phuket/3073/2013-like virus.

Children

Children above the age of 6 months who are at 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. A guideline from the Danish Paediatric Society is available (in Danish) at www.paediatri.dk.

Children aged from 6 months through 8 years 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. For correct measuring of the paediatric dose, please see the package leaflet of the vaccine in question.

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, who cannot be vaccinated.

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 Authority therefore recommends influenza vaccination of all pregnant women in their 2nd or 3rd trimester. 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 breastfeeding period.

HIV infectees

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 see their GP to receive free influenza vaccination.

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 reaches 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 a reaction resembling an anaphylactic shock should not be vaccinated. Allergy to formaldehyde will most frequently manifest itself as contact dermatitis in connection with which patch tests may be positive. However, this 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.

Registration of vaccinations

All influenza vaccinations shall be registered in the Danish Vaccination Register (DVR) in accordance with Executive Order on Access to and Registration etc. of Medicinal Product and Vaccination Information (in Danish). If the vaccination information is not automatically recorded to the DVR via integration with the electronic patient record used, vaccinations can be registered at www.fmk-online.dk.

Influenza surveillance

Statens Serum Institut's influenza surveillance will be in place as from Week 40. This year, data from the influenza surveillance will be updated on the SSI website weekly, and news will only be published if the influenza situation changes.

(T.G. Krause, L.K. Knudsen, Department of Infectious Disease Epidemiology)

Link to previous issues of EPI-NEWS

28 September 2015