EN    EN EN 
 
EN    EN  COMMISSION OF THE E UROPEAN COMMUNITIES 
Brussels, 15.9.2009 
SEC(2009) 1189 final 
  
COMMISSION STAFF WORKING DOCUMENT 
 
Vaccination strategies a gainst pandemic (H1N1) 2009  
 
accompanying the 
 
COMMUNICATION FROM THE CO MMISSION TO THE EUROPEAN 
PARLIAMENT, THE COUNCIL, THE EUROPEAN ECONOMIC AND SOCIAL 
COMMITTEE AND THE COMMI TTEE OF THE REGIONS 
Pandemic (H1N1) 2009  
{COM(2009) 481} 
{SEC(2009) 1188} {SEC(2009) 1190} {SEC(2009) 1191} {SEC(2009) 1192} 
 
EN 2   EN INTRODUCTION  
In April 2009, a novel strain of  a human influenza A(H1N1) vi rus was identified that had 
caused illness in Mexico and the United States first, in March and April 2009. 
On 11 June 2009, the World Health Organisation  (WHO) declared a pandemic, caused by the 
novel influenza A(H1N1) virus, hereafter call ed 'pandemic (H1N1) 2009 influenza virus'. 
This declaration was in line with WHO’s globa l influenza preparedness plan where phase 6, 
the pandemic phase, is defined as the virus causi ng sustained community-level outbreaks in at 
least two countries in one WHO region and in at least one othe r country in a different WHO 
region. The declaration therefore reflected the spread of the ne w virus, not the severity of 
illness caused by it. 
Current experience is that some ‘higher risk’ groups are more likely to suffer severe illness if 
infected (people with u nderlying chronic conditions1, pregnant women and young children). 
Most patients have suffered only a mild, self -limiting illness and the health services have 
generally coped. 
Notwithstanding the moderate symptoms caused by the pandemic (H1N1) 2009 influenza 
virus so far, the wide spread of the virus pos es a potentially serious threat. In the winter 
ahead, the virus could transmit more easily and ther e will be more other respiratory infections 
than in summer. In addition, it cannot be rule d out that the pandemic (H1N1) 2009 influenza 
virus might mutate or exchange genetic materi al with other influenz a viruses, which could 
lead to it causing a more severe illness. 
Vaccines play an important role in the prepar ations for the increase in infections by the 
pandemic (H1N1) 2009 influenza virus exp ected from the autumn onwards. Indeed, 
vaccination with a pandemic vaccine effectiv e against the pandemic (H1N1) 2009 influenza 
virus can be considered as one of the most ef fective public health measures in that it both 
offers protection to the individual and prev ents onward transmission. Obviously, the public 
health response should not rely on vaccinati on alone but should also include other public 
health measures, both pharmaceutical (e.g. anti virals) and non-pharmaceutical (e.g. social 
distancing or personal protective equipment).  
As specific vaccines cannot be developed until the pandemic influenza strain has been 
isolated, the vaccine will initially be availa ble in only limited quantities and demand may 
initially be higher than supply. In addition, the yield of pandemic (H1N1) 2009 influenza 
antigen to produce vaccines might be lower than the yield usually  seen for seasonal influenza 
strains, which, in turn, would limit supply. The initi al limited availability of vaccines, together 
with the potential need for a la rge-scale vaccination campaign, pos es challenges to  healthcare 
systems and highlights the need for a carefully planned vaccination strategy. 
This Commission Staff Working Document outli nes a possible vaccination strategy based on 
the evidence currently available, while recogn ising that the responsibility for developing a 
vaccination strategy against pandemic (H1N1) 2009 lies with the Member States. Therefore, 
                                                 
1 E.g. chronic respiratory diseases; chronic cardiovascul ar diseases, excluding isol ated mild hypertension; 
chronic metabolic disorders, notably diabetes; chronic renal and hepatic diseases; persons with 
congenital or acquired immunodeficiency; chronic neurological or neuromuscular conditions. 
 
EN 3   EN Member States may develop different vaccina tion strategies, taking into account their 
epidemiology, health service structures and availa ble resources. It should also be stressed that 
any vaccination strategy might need to be ad apted as more epidemiological, clinical and 
pharmaceutical evidence becomes available an d as the pandemic progresses. Vaccination 
strategies against pandemic (H 1N1) 2009 will therefore need to be reviewed regularly.  
1. POSSIBLE OBJECTIVES  OF VACCINATION  
On 7 July 2009, the WHO Strategic Advisory  Group of Experts (S AGE) on Immunisation 
identified three objectives that countries coul d adopt as part of their pandemic vaccination 
strategy: 
• protect the integrity of the healthcare system and the country’s critical infrastructure, 
i.e. maintain essential services; 
• reduce morbidity and mortality, i.e. protect the vulnerable; 
• reduce transmission of the pandemic virus with in communities, i.e. limit the speed of 
spread of infection and limit th e burden on the healthcare system. 
The categories of people who would be covered by  those three objectives are listed in Table1. 
Table 1 . Rough estimates2 of the numbers of EU citizens who would be covered by the three 
objectives identified by SAGE 
 
Population % of the whole 
population 
Objective: maintain essential services (approximately 6  %) 
Healthcare workers 10,000,000 2  %
Workers in other essential services 20,000,000 4  %
Subtotal 30,000,000 6  %
Objective: protect the vulnerable (approximately 29  %) 
Very young children (0-24 months) 10,000,000 2  %
Persons aged between 25 months and 64 years 
with underlying chronic conditions increasing the 
risk of severe disease 40,000,000 8  %
Pregnant women  7,500,000 1.5  %
People aged 65 and older 85,000,000 17  %
Subtotal 142,500,000 28.5  %
                                                 
2 Note: percentages have been rounded, so the subtotals do not add up exactly. 
 
EN 4   EN Objective: limit the speed of spread of infection and the burden on the healthcare system 
(approximately 65  %) 
Healthy children and adolescents aged between 
25 months and 18 years 85,000,000 17  %
Healthy adults not included in the previous groups 240,000,000 48  %
Subtotal 325,000,000 65  %
Total population (EU27) 500,000,000 100.0  %
1.1. Maintaining essential services 
During a pandemic, there is likely to be a de gree of absenteeism from work. In the United 
Kingdom, it has been  estimated that 12  % of the adult popula tion will be off work at the peak 
of the pandemic3. A survey led by researchers at th e Johns Hopkins Bloomberg School of 
Public Health found that approximately one in  six public health workers (approximately 16  %) 
said they would not report to work during an  influenza pandemic, regardless of its severity4. 
Organisations will need to assess, in their business continuity plans, whether such levels of 
absenteeism would be disruptive to their activities.  This applies, in part icular, to organisations 
which deliver services essentia l to keep society working. Examples include but are not limited 
to: 
• Healthcare workers; 
• People working in command and control centres and in essential services such as (in no 
specific order): 
• electronic communications; 
• security (law and order); 
• civil protection services a nd other first responders; 
• electricity production and distribution; 
• water supply; 
• food production and distributi on (including transport); 
• oil and gas recovery, processing and distribution (including transport); 
• public transport systems; 
                                                 
3
 http://www.dh.gov.uk/en/Publicationsandstatis tics/Publications/PublicationsPolicyAndGuidan
ce/DH_102892 . 
4 Barnett, D.J., Balicer, R.D., Thompson, C.B., Storey , J.D., Omer, S.B. et al., 2009 Assessment of Local 
Public Health Workers’ Willingness to Respond to Pandemic Influenza through Application of the 
Extended Parallel Process Model. PLoS ONE 4(7): e6365. doi:10.1371/journal.pone.0006365. 
 
EN 5   EN • financial and logistics services. 
Essential services might need to be target ed for vaccination against pandemic (H1N1) 2009 
influenza, especially those where the estimated levels of absenteeism would disrupt operation 
of the service. This applies, in  particular, to healthcare worker s who, in addition, will have to 
cope with far higher number s of patients than usual. 
1.2. Protecting the vulnerable 
According to the current evidence on pandemic (H1N1) 2009, the following population 
groups are considered at higher risk of severe pande mic (H1N1) 2009 influenza infection than 
the general population: 
• people with underlying chronic conditions in creasing the risk for severe disease (e.g. 
chronic respiratory diseases; chronic cardiov ascular diseases, excluding isolated mild 
hypertension; chronic metabolic disorders, no tably diabetes; chronic renal and hepatic 
diseases; persons with conge nital or acquired immunodeficien cy; chronic neurological or 
neuromuscular conditions.), 
• young children (especially thos e aged 0 – 24 months), 
• pregnant women. 
Details of the evidence of the risk of people de veloping severe disease when infected with the 
pandemic (H1N1) 2009 influenza virus are ava ilable in the European Centre for Disease 
Prevention and Control (ECDC) risk assessment, which is updated regularly5. As further 
epidemiological data become available, the pop ulation groups consider ed vulnerable and at 
risk of severe infections could change. 
The above-mentioned groups differ somewhat fr om the groups for whom many countries 
recommend seasonal influenza immunisation. Notably, elderly people are missing. It is 
speculated that elderly people ar e affected less because they possibly have some residual 
immunity from previous exposur e to viruses in some ways si milar to the pandemic (H1N1) 
2009 influenza virus. However, it seems that not  all elderly people are immune and those who 
do become infected suffer a more severe diseas e. Therefore some elde rly people are at higher 
risk of developing severe disease, but th ey cannot be readily identified. Given this 
uncertainty, there is merit in including th is age group as a targ et for vaccination. 
1.3. Limiting the spread of infection: projec tion on immunisation coverage needed 
To reduce or eliminate influenza from the host population, a reduction in transmission is 
necessary. This can be achieved by mean s such as vaccination. Vaccination is, 
epidemiologically speaking, an attemp t to reduce the reproductive number R 0 (the number of 
secondary cases produced by each infectious case) to below 1. 
The decisive question is what fraction of the population needs to be vaccinate d in order to 
produce enough immune peopl e to make sure that the infecti ous persons will not be able to 
infect one other person on average. If the fraction of the population susceptible is small 
                                                 
5 http://www.ecdc.europa.eu/en/H ealth%5Ftopics/novel%5Finfluenza%5Fvirus/2009%5FOutbreak/. 
 
EN 6   EN enough, the probability that an infective host w ill come into contact with a susceptible 
individual before recove ring will be very low. 
For the current influenza pandemic, the estimates point to an R 0 value of about 1.6. Assuming 
a hypothetical vaccine efficacy of 70  % (as often seen with seasona l influenza vaccines), the 
fraction of the population which would have to be vaccinated would be at least 54  %6. 
This (over-)simplified calculation assumes th at everybody would be equally affected by the 
disease, that there would be random mixing of the population, th at the vaccine would have the 
same efficacy in everybody and that protective (susceptible) efficacy is equal to infectiousness efficacy. Nevertheless, it gives a rough indication to support policy decisions 
on immunisation coverage. 
Epidemiological data on pandemic (H1N1) 20 09 influenza suggest that immunisation of 
children and young adults could be particul arly effective in reducing transmission. 
2. P
OTENTIAL TARGET GROUPS AND PRIORITY GROUPS FOR VACCINATION  
Target groups are all the people for whom vaccination can be recommended. 
Priority groups are the people within the targ et groups who should be vaccinated first if not 
enough vaccine is initiall y available for everyone in the ta rget groups. Even if enough vaccine 
were available, distributing large quantities of vaccine and vaccinating large numbers of 
people takes time. 
Balancing the three objectives described previo usly, the following can be  considered potential 
target groups  for vaccination, covering between 34  % and 60.5  % of the total population: 
• Maintaining essential services: 
• healthcare workers (2  %); 
• workers in other essential services (4  %). 
• Protecting the vulnerable: 
• all persons aged from 6 months to 24 months (1.5  %)7; 
• all persons aged from 25 months to 64 years with underlying chronic conditions 
increasing the risk of  severe disease (8  %); 
• pregnant women (1.5  %); 
                                                 
6 If a vaccine confers complete immunity on ever yone who is immunised, a fraction f > 1 — (1/R 0) 
would need to be vaccinated. If the vaccine confer s immunity on only a frac tion V1 of th e population 
(not all vaccinated people will have a sufficient im mune response to the vaccine to build up protective 
immunity), then f = V times V1 and thus V > (1 — (1/R 0)) / V1. 
7 The 0–6 months age group has not been included, given the absence of a vaccine for this age group. 
This vulnerable age group can be protected by other pharmaceutical and non-pharmaceutical public 
health measures. Immunising pregnant women will pr obably also afford some protection to newborns 
via maternal antibodies. 
 
EN 7   EN • all persons aged 65 years and more (17  %)8. 
• Limiting the spread of infection, depending on the epidemiology, health  service structures 
and available resources: 
• all persons aged from 25 months up to young adults, e.g. up to 18 years to cover 
children and young adults up to the end of secondary education (17  %) or 24 years 
to cover children and young adults up to  the end of tertiary education (26.5  %). 
It should be stressed that the eventual target  groups will depend on th e national targets set by 
the Member States. In some cases, this may be  the entire population and in other cases only 
specific groups. 
However, it is unlikely that th e vaccine will be immediately avai lable for all target groups at 
the same time and therefore, it is necessary to  define priority groups. The European Union 
Health Security Committee and the Early Wa rning and Response authorities (HSC/EWRS) 
adopted on 25 August 2009 a policy statement9 proposed by the European Commission in 
which the following 19.5  % of the population was identified for prioritisation  when limited 
amounts of vaccine are available: 
• healthcare workers (2  %); 
• all persons aged from six months on with underlying chronic conditions 
increasing the risk of  severe disease (16  %); 
• pregnant women (1.5  %). 
This prioritisation is designed to include the es sential services which f ace the highest risk of 
being overloaded during a pandemic and also the vulnerable groups at  greatest risk of severe 
illness following infection with the pa ndemic (H1N1) 2009 influenza virus. 
It should be stressed that the responsibility for developing a vaccination strategy against 
pandemic (H1N1) 2009 lies with the Member Stat es. Therefore, Member States may develop 
different vaccination strategies , taking into account  their epidemiol ogy, health service 
structures, available resources and cost -effectiveness of available vaccines. 
The decisions on target groups and priority groups could also be  influenced by the choice of 
pandemic (H1N1) 2009 influenza vaccine (e.g. ad juvanted versus unadjuvanted vaccine or 
inactivated whole virion vaccine  versus surface antigen/split vi rus vaccine) and by marketing 
authorisation conditions for the av ailable vaccines. and by the bene fit/risk profile of available 
vaccines for individual population groups. 
It should also be added that some of the above-mentioned groups might change as more 
epidemiological, clinical and pharmaceutical ev idence becomes available and as the pandemic 
progresses. Potential target groups and prio rity groups for vaccination against pandemic 
(H1N1) 2009 influenza will therefore need to be reviewed regularly. 
                                                 
8 Given the uncertainty on whom has residual immunity from previous exposure to viruses in some ways 
similar to the pandemic (H1N1) 2009 influenza virus,  there is merit in including this age group as a 
target for vaccination (see Section 1.2). 
9 http://ec.europa.eu/health/p h_threats/com/Influenza/docs /HSC_EWRS_statement_en.pdf 
 
EN 8   EN 3. TIMING OF VACCINATION CAMPAIGNS  
Vaccination of priority groups should star t as soon as pandemic (H1N1) 2009 influenza 
vaccines become available. This should be fo llowed by vaccination of target groups. It is 
recommendable to continue to vaccinate unimm unised individuals and not keep vaccine in 
reserve for later administration of the second dos e. The second dose can be given three to four 
weeks later, as additional supplies become available. 
4. VACCINATION CAPACITY OF HEALTHCARE SYSTEMS  
4.1. Vaccine supply 
First of all, vaccine supply will determine th e vaccination capacity of  healthcare systems. 
Prudent estimates put the annual global producti on capacity for pandemic influenza vaccine at 
2.45 billion monovalent doses. European influe nza vaccine manufact urers account for 60  % of 
the global production capacity, i.e. approxima tely 1.5 billion monovalent doses, of which a 
large proportion could be expor ted outside Europe, as is th e case for seasonal influenza 
vaccines. Also, the full annual production will only gradually become available. As a result, especially in the initial phase, demand coul d be higher than suppl y. Anticipating limited 
supplies, an increasing number of Member States have concluded advance purchase 
agreements with one or more influenza vaccine  manufacturers to reserve a set proportion of 
the available production capacity fo r pandemic influenza vaccine. 
4.2. Logistics 
Appropriate arrangements will need to be made for distributing and storing sufficient 
quantities of vaccines and medical material (syri nges, needles, alcohol swabs, etc.), including 
sufficient capacity to maintain the cold chain of vaccines. Admi nistration of vaccines to target 
populations as soon as vaccine arrives should be the aim. 
4.3. Vaccination capacity 
To avoid overburdening healthca re facilities in th e event of a mass vaccination campaign, 
Member States could consider spreading the se ttings in which vaccination will take place 
between healthcare facilities, schools, work pl aces, function venues, etc., in accordance with 
any provisions in national and regional pandemi c preparedness plans. In such cases, Member 
States would need to consider whether the chosen settings will be capable of providing vaccine, registering vaccination, recalling patients for their s econd dose within three or four 
weeks, depending on which vaccine is used, a nd monitoring and reportin g adverse events.  
Depending on the results of the scientific studies  on the vaccine, either one or two doses of 
vaccine are expected to be needed to ach ieve protective immunity. Currently we are 
proceeding on the assumption of two doses; howeve r should the scientific  data indicate that 
one dose will be sufficient, more vaccines would become available to v accinate in a shorter 
time those for whom vaccination can be recomme nded. In case two doses would be needed, it 
is recommendable to give the tw o doses of the same vaccine, as no clinical data are available 
on the interchangeability of different vaccin es against pandemic (H1N1) 2009 influenza. 
Also, if doses of two different vaccines were  given, it would be di fficult to link adverse 
events, which do not manifest themselves shortl y after immunisation, to a particular vaccine. 
 
EN 9   EN Member States will need to take into acc ount in their budgets th e financial and human 
resource implications of procuring and delivering the vaccine. As a planning assumption to ensure sufficient numbers of healthcare staff, a single vaccinator can vaccinate an estimated 
50 to 100 individuals a day. 
5. M
ONITORING AND EVALUATION OF VACCINATION CAMPAIGNS  
5.1. Vaccine safety 
The European Union has a comprehensive and effective monitoring system for reporting on 
and assessing the safety and efficacy of each medi cinal product after it has been authorised. In 
addition, the European Medicines Agency (E MEA) has published sp ecific guidance on the 
pharmacovigilance plan which forms part of th e risk management plan that has to be 
submitted with the application for marketing authorisation for any pandemic influenza vaccine
10. 
It is possible that when Member States launch a vaccination campaign against pandemic 
(H1N1) 2009, only limited safety data will be av ailable. Therefore, Member States could 
consider establishing additional enhanced active surveillance for serious adverse events. Options could include using sentinel hospitals to  screen actively for adverse events following 
immunisation or asking vaccinating doctors or nurs es to report to the national authority on a 
weekly basis, irrespective whether they have  seen any adverse event or not. Establishing 
protocols for assessing individual suspected ca ses of adverse events following immunisation, 
in order to ensure best practice, and determin ing background incidence rates of conditions on 
the list of adverse events of special interest  before embarking on vaccination campaigns could 
be other key tools. 
The activities described above will be essential in order to monitor closely any unexpected 
serious adverse reactions and allow the risk/benefit to be reassessed scientifically if necessary. If a vaccine shows serious side-effects, the Commission may — after a scientific assessment 
— vary, suspend or revoke its marketing authorisation. 
Public confidence, and therefore the success of any vaccination cam paign against pandemic 
(H1N1) 2009, will depend on the pharmacovigilan ce system in the EU working properly. 
5.2. Vaccine effectiveness 
Assessing and monitoring the eff ectiveness of pandemic vaccines is essential after vaccines 
are placed on the market and distributed for administration. Although strain-specific 
pandemic vaccines are expected to be effec tive against pandemic (H1N1) 2009 influenza, 
early availability of estimates of  their effectiveness will allow better benefit/risk analysis if 
adverse events are reported following immuni sation. Similarly, it will also allow better 
management of and response to reports of v accine failures, i.e. of people contracting 
pandemic (H1N1) 2009 influenza despite having been vaccinated. 
The effectiveness of the pandemic influenza vaccine will be studied by the vaccine 
manufacturers in collaboration with regulator y authorities. Effectiveness studies proposed 
after authorisation will be described in the ri sk management plan which has to be submitted 
                                                
 
10 http://www.emea.europa.eu/pdfs/human /pandemicinfluenza/35938109en.pdf. 
 
EN 10   EN with the application for marketing authorisat ion. Activities to monitor effectiveness could 
include specific effectiveness studies, pros pective observational safe ty studies including 
effectiveness outcomes and the use of other sources of data such as local networks or sentinel 
physicians. 
The ECDC is working with its partners (E piconcept and Member States in the I-MOVE 
partnership11) to extend the mechanism it has devel oped for seasonal influenza to pandemic 
vaccines. It also maintains close links with its  international partners planning to monitor the 
effectiveness of vaccines agains t pandemic (H1N1) 2009 influenza. 
Should vaccine effectiveness be found to be poor , additional or altern ative public health 
measures could be taken (e.g. an tivirals) and further investiga tions could be conducted to 
improve vaccine use or composition. 
                                                 
11 More information can be found at: 
http://ecdc.europa.eu/en/publications/Publications/0907_TED_Influenza_AH1N1_Measuring_Influenza
_Vaccine_Effectiveness_Protocol_Case_Control_Studies.pdf .