2Flu vaccination programme 2017–18
Disease burden in the 2017/18 season
8.NHS Improvement have estimated that up to 4,000 beds each day could have been used by flu patients, and that at the peak of the season up to 500 patients were admitted with flu per week—significantly more than in previous winter flu seasons.9
9.Dr Sue Crossland, Vice President of the Acute Medicine Society, provided us with a view from her frontline experience at Calderdale Royal Hospital in Halifax. She told us that in the 2017/18 season her hospital had seen 200 positive flu admissions by March, compared to just 33 in 2016/17. She also reported observing a significant proportion of young people admitted and an increased requirement for intensive care support.10
10.Professor Paul Cosford, Director for Health Protection and Medical Director at Public Health England, provided us with further information about the high rate of hospitalisation due to flu in the season up to the oral evidence session in March 2018:
The interesting thing is that flu this season is not significantly worse than it was last season, or two years before that, in terms of mortality. What we are seeing this season is a very high rate of hospitalisation compared with previous years, so the pressures on NHS colleagues have been very real. If you look at flu circulating in the community, it is a moderate flu season, whereas, if you look at hospitalisations, the figure is very high and has been very high for several weeks.11
Flu vaccines offered in the 2017/18 season
What viruses were in the vaccines?
11.There are three types of human flu virus: A, B and C. Flu A and B are responsible for most clinical illness and are included in all vaccines offered in the national flu vaccination programme. Type A viruses are further classified into subtypes such as ‘A(H1N1)’. Type B viruses are classified further through the lineage of the virus, for example ‘B-Victoria’. Both A and B virus types can be further broken down into strains within the subtypes or lineages.12
12.Flu vaccines may include either three virus strains—two influenza A viruses and one Influenza B virus (Trivalent vaccine) or, since the 2013/14 season, four virus strains—two of both influenza A and B viruses (Quadrivalent vaccine).13
13.The specific flu viral strains to be included in the flu vaccination for the Northern hemisphere are decided by the World Health Organization each year in February or March before the start of winter flu season (i.e. for the flu vaccines to be offered in the 2018/19 season, a decision was taken on 22 February 2018). At this time, recommendations were made for which virus strains should be included in trivalent and quadrivalent vaccines.
14.The Deputy Chief Medical Officer, Professor Jonathan Van-Tam, explained how these decisions were made by the World Health Organization:
The World Health Organisation calls what is known as a strain selection meeting, where influenza virologists from around the world gather twice a year. The best brains in influenza virology come together and formulate an opinion on what are the best strains to put into the vaccine. We as an individual nation do not have any choice, because the manufacturers are committed to following the World Health Organisation instructions.14
15.After the WHO decision is made, manufacturers start to produce vaccines in preparation for the flu season and from this time, there is no opportunity to change what virus strains are in the vaccines. Professor Van-Tam described this time lag as one of the scientific problems with the flu vaccine:
From that moment, we are hostages to virological fortune, if you like, as regards anything that might change between March and October. The volumes required—hundreds of millions of doses for the northern hemisphere alone—make it impossible to make a snap decision in July that something needs to change. We have to live with the decision that our experts hand to us in mid-February.15
16.The WHO 2017/18 recommendations on the viruses to be included in the vaccine in use in the northern hemisphere were published in February 2017. The WHO recommended that trivalent (three virus) vaccines should contain:
- an A/Michigan/45/2015 (H1N1)pdm09-like virus;
- an A/Hong Kong/4801/2014 (H3N2)-like virus; and
- a B/Brisbane/60/2008-like virus.16
The WHO recommended that the quadrivalent (four virus) vaccines should also contain a second influenza B virus: “a B/Phuket/3073/2013-like virus, a B/Yamagata-lineage virus”.17
17.Most flu vaccines produced are ‘inactivated’. This means that the virus in the vaccine has been killed. However, the nasal spray flu vaccine offered to children in the UK contains weakened (or ‘attenuated’) live flu viruses.18
UK vaccine recommendations
18.Recommendations to UK departments of health relating to eligibility for the flu vaccination programme and the types of vaccine offered to eligible groups are made by the Joint Committee on Vaccination and Immunisation (JCVI), an independent departmental expert committee. The JCVI keeps emerging evidence on vaccinations under review and provides new advice based on this.19
19.The Public Health England Green Book on Immunisation against infectious disease (‘the Green book’) provides up-to-date guidance on the flu vaccines to be used in eligible groups.20 In the 2017/18 season vaccinations were recommended for different groups. We set these out in the paragraphs that follow.
Children
20.It was advised that children were offered the only live vaccine used in the flu vaccination programme—the live attenuated intranasal vaccine, LAIV Fluenz-Tetra (LAIV). This is a quadrivalent vaccine. Professor Pollard explained why the live vaccination was more effective in children:
The trials show that it works better than inactivated vaccines, because the live vaccine stimulates a better immune response than the inactivated vaccine in children. The problem for adults is that we all have some immunity already. That stops the live vaccine working so well, because it kills some of the vaccine. Therefore, adults have rather poor responses to the live vaccine. That is the main reason for the difference.21
21.Where there are contraindications to the live vaccine, such as in children who are immunocompromised, the Green book advises that the inactivated quadrivalent vaccine should be offered.22
Eligible adults
22.The JCVI recommendation in 2017/18 was that all adults eligible for the flu vaccination should be offered either the trivalent or quadrivalent vaccine, with the decision made at a local level by GPs through their procurement choices. As noted above, the trivalent vaccine includes two flu A viruses, and one flu B virus. The quadrivalent vaccine includes an extra flu B virus strain (in 2017/18 this was a B-Yamagata flu virus).23
23.For the 2017/18 flu season, Professor Pollard told us that whilst the Green book had set out a preference for the quadrivalent vaccination there had not been a strong preference:
The words that we use are that we “have a preference” for the quadrivalent. However, the data we have looked at have not been strong enough for us to say, “You really ought to have the quadrivalent, because it is so much better.” The previous seasons’ data did not support a strong recommendation for that.
[...] When you add the second B strain, you get a bit of additional benefit, but the difference is not huge, because the one B strain gives you some protection against other B strains. You really need to have both of the As. However, for the Bs, you get so much protection from one B strain that having the other is a fairly marginal additional benefit.24
24.Professor Powis explained that NHS England was responsible for commissioning the adult seasonal flu vaccination in England. He said that GPs were asked to procure up to ten months in advance and they took into account a number of sources of guidance when making these decisions, such as the annual flu letter and the Green book. He set out what considerations NHS England regional teams and commissioners would make with regards to spending on vaccination:
Commissioners and NHS England regions, both of which can hold budgets to reimburse general practitioners and pharmacists in their procurement, also have a duty, quite reasonably, to use taxpayers’ money efficiently and to consider what they spend on vaccination in the round, against everything else that they commission. In the decisions that they take locally, they will weigh up the evidence that you have heard from JCVI, which is in the Green Book, and place that in the context of all the commissioning decisions that they make.25
25.Professor Cosford told us that the best estimate was that two-thirds of individuals vaccinated in the 2017/18 season had received the trivalent vaccine and one third had received the quadrivalent.26
Trivalent vs quadrivalent—what impact did this have?
26.Due to the circulation of the B-Yamagata virus in the 2017/18 season, concerns had been expressed that increased hospital admissions may, to some extent, have been related to the use of the trivalent flu vaccination rather than quadrivalent vaccination in certain parts of the country. The President of the Acute Medicine Society, Dr Nick Scriven, stated that if the quadrivalent vaccine had been used instead of the trivalent vaccine, “probably about half the cases that are coming into hospital […] may have been prevented.”27 Dr Sue Crossland, Vice President of the Acute Medicine Society, told us that “even a marginal benefit from a quadrivalent vaccine might [have eased] some of the pressures that we are seeing day in, day out on the frontline”.28
27.Professor Andrew Pollard, Chair of the JCVI, disputed the claims made by Dr Nick Scriven. He accepted that, due to the circulating strains, it may have made some difference if the quadrivalent vaccine had been widely used but argued that it would not have made a significant difference, nor would it have prevented half the cases.29 He explained that the impact was dependent on the circulating strains and the effectiveness of the vaccine:
Even in really fantastic flu seasons, where the vaccine matches the strain very well, we are pretty happy if we get a vaccine that is 50% to 60% effective. That means that, even if you had the vaccine that was perfectly matched, half of the cases would still not be prevented in those who are vaccinated. [...] It is right to say that a lot of B strains were causing disease. If vaccines were 100% effective, the assertion would have been right, but they are not. That is the problem.30
28.Professor Cosford provided further information on the virus strains that had been circulating in the 2017/18 season, and reported that the trivalent vaccine appeared to have offered some cross protection against the B-Yamagata strain, despite this not being included in the vaccine:
It is a very early estimate, so we cannot be certain that it will be exactly the same when the final season estimate comes out, but the vaccine effectiveness data that we published last week suggest that, against flu B, of all strains, we have had roughly 50% protection; 53% is the point estimate. That suggests that, although the trivalent vaccine did not include the Yamagata strain, it has been offering quite a significant amount of protection against both B-Yamagata and B-Victoria, which was in the vaccine. That is in addition to the third of people or so who have had the quadrivalent vaccine.
29.Flu vaccine effectiveness varies from year to year, as noted above. Professor Pollard explained that “a problem with the flu vaccine is that in some years it will not work because the strain will not match, and in some years it will work because the strain matches very well”.31
30.Public Health England published updated UK flu vaccination effectiveness data in July 2018 for the 2017/18 season.32 The figures have wide confidence intervals (see table at the end of the paragraph), meaning that there is uncertainty in exactly how effective vaccines were. However, the figures suggest that the vaccines (especially those used in adults) were less effective in 2017/18 than in previous years. The quadrivalent nasal spray vaccination for children offered good protection against one flu A virus (A(H1N1)) and against flu B but was not clearly effective against the other A flu virus (A(H3N2)). In the eligible groups under 65 the vaccines were effective against A(H1N1) but not as effective against flu B or A (H3N2). Commenting on the figures, Professor Paul Cosford, Director for Health Protection and Medical Director at Public Health England, explained that the vaccines could have offered lower effectiveness against flu A(H3N2) due to a number of factors, including “a suboptimal match between the main circulating A(H3N2) viruses and the vaccine”.33 As with previous years, the vaccines have been the least effective in the over 65s.
|
Group |
A(H3N2)adjusted VE (95% CI) |
A(H1N1)pdm09 adjusted VE (95% CI) |
B adjusted VE (95% CI) |
All adjusted (95% CI) |
|
2–17 year old (LAIV only) |
-75.5(-289.6, 21.0) |
90.3 (16.4, 98.9) |
60.8 (8.2, 83.3) |
26.9 (-32.6, 59.7) |
|
18–64 year old (any vaccine) |
-14.7 (-72.7, 23.8) |
69.1 (11.4, 89.2) |
18.2 (-15.1, 41.9) |
12.2 (-16.8, 34.0) |
|
>65 year old (any vaccine) |
16.8 (-74.2, 60.3) |
NA |
13.2 (-68.4, 55.2) |
10.1 (-54.8, 47.8) |
|
All age |
-16.4 (-59.3, 14.9) |
66.3 (33.4, 82.9) |
24.7 (1.1, 42.7) |
15.0 (6.3, 32.0) |
CI: confidence interval; VE vaccine effectiveness; NA: not applicable
*Adjusted for age group, sex, month, pilot area and surveillance scheme.
Source: Public Health England, Flu vaccine effectiveness in 2017 to 2018 season, 18 July 2018
New recommendations for the 2018/19 season
Quadrivalent vaccine for all eligible groups under 65
31.Professor Pollard told us that in the 2017/18 season and previous seasons the evidence had not supported a strong recommendation to offer the quadrivalent over the trivalent vaccine. However, recent evidence reviewed by the JCVI led to a specific new recommendation that all eligible adults under 65 should be offered the quadrivalent vaccination.34 The Green book now states that “there are relatively small health benefits to be gained by the use of quadrivalent vaccines, compared with trivalent vaccines, in the elderly”, but that “the benefit is more substantial in at-risk adults under 65 years of age, including pregnant women”.35
Adjuvanted vaccine for the over 65s
32.Previously, the flu vaccines used during the national flu vaccination programme had been less effective in older adults. Professor Pollard explained that this was due to the immune system not working as well in this group.36 Up until recently, there had been no other alternative that worked better. However, a new vaccine—the adjuvanted vaccine—has recently been licensed in the UK. An adjuvant is a substance that is added to a vaccine in order to improve the immune response.
33.The JCVI reviewed the evidence on the new vaccine in October 2017 and found that it had higher effectiveness in the over 65s compared with the current vaccine.37 Modelling data provided by PHE also showed that the adjuvanted trivalent influenza vaccine was cost effective in the over 65 group. The Green book was updated in December 2017 to reflect this recommendation.38
34.Professor Van-Tam described the new vaccine as a “game-changer in terms of how the elderly immune response works in relation to a vaccine”. He said that modelling for how it would work in the UK suggested that there would be an expected 20% improvement in vaccine effectiveness.39
35.In February 2018, following the change in recommendations, NHS England wrote to all Clinical Commissioning Groups (CCGs), GPs, pharmacies and NHS hospital trusts to advise them of the new guidance from the JCVI. GP practices were recommended to purchase the new adjuvanted trivalent vaccine for those aged 65 and older and the quadrivalent vaccine for eligible groups under 65.40
36.We are concerned about the impact that higher levels of flu had on frontline NHS hospital staff in the 2017/18 season, and reports that this could have been reduced by changes to the vaccination recommendations. However, we heard that the evidence available did not support the use of the quadrivalent vaccine in all eligible groups and we are convinced by arguments made to us that whilst the B-Yamagata strain was responsible for a significant burden of disease in the 2017/18 season, use of the quadrivalent vaccine in all individuals would not have made a huge difference to the additional burden placed on frontline staff in the NHS.
37.We have heard that flu vaccine effectiveness varies from year to year and is dependent on how well the strains within the vaccine match those circulating in the flu season. In the 2017/18 season the vaccine was less effective than it had been in previous seasons. Nevertheless, we agree with health professionals that the flu vaccine is still the most effective protection available against the serious effects of flu and it is critical for eligible groups to be vaccinated.
38.We welcome changes introduced to flu vaccines in response to new evidence which seek to further improve effectiveness in future seasons. We were reassured by the response of Joint Committee on Vaccination and Immunisation (JCVI) and Public Health England (PHE) to this new evidence and welcome the specific guidance on use of both the quadrivalent vaccine for eligible individuals under 65 and the new adjuvanted vaccine for the over 65s.
9 NHS Improvement, NHS review of winter 2017/18, 7 September 2018
12 World Health Organization, ‘Influenza (seasonal)’ accessed 16 October 2018
13 World Health Organization, ‘Influenza (seasonal)’ accessed 16 October 2018
16 World Health Organization, Recommended composition of influenza virus vaccines for use in the 2018–2019 northern hemisphere influenza season, 22 February 2018
17 World Health Organization, Recommended composition of influenza virus vaccines for use in the 2018–2019 northern hemisphere influenza season, 22 February 2018
18 Public Health England Immunisation against infectious disease, The Green Book (Chapter 19: Influenza), 15 August 2018
20 Public Health England Immunisation against infectious disease, The Green Book (Chapter 19: Influenza), 15 August 2018
22 Public Health England Immunisation against infectious disease, The Green Book (Chapter 19: Influenza), 15 August 2018
23 World Health Organization, Recommended composition of influenza virus vaccines for use in the 2018–2019 northern hemisphere influenza season, 22 February 2018
26 Q35. At Q22 Professor Cosford explained the types of vaccines ordered by GPs: “This year, roughly one third of the vaccine ordered by GPs across the country was quadrivalent and two thirds was trivalent. Therefore, a significant proportion of the adult groups received quadrivalent, anyway”.
27 The Society for Acute Medicine, Choice of flu vaccine ‘has increased risk of admissions’ – SAM president, 18 January 2018
32 Public Health England, Flu vaccine effectiveness in 2017 to 2018 season, 18 July 2018
33 Public Health England, Flu vaccine effectiveness in 2017 to 2018 season, 18 July 2018
34 Public Health England Immunisation against infectious disease, The Green Book (Chapter 19: Influenza), 15 August 2018
35 Public Health England Immunisation against infectious disease, The Green Book (Chapter 19: Influenza), 15 August 2018
37 Public Health England, Summary of data to support the choice of influenza vaccination for adults in primary care access, 29 January 2018
38 Public Health England Immunisation against infectious disease, The Green Book (Chapter 19: Influenza), 15 August 2018
40 NHS England, British Medical Association and Pharmaceutical Services Negotiating Committee,
Flu vaccinations for 2018 and planning flu clinics, 2 August 2018
Published: 18 October 2018