Influenza epidemic: what to expect from vaccine evaluation?

10 January 2019

The flu epidemic is late, but its onset is still expected. Every year in France, it affects an average of 2.5 million people and causes about 4000 to 6000 deaths, mainly among the elderly. To avoid them, a flu vaccination campaign is organized every fall. It is the subject of an incentive policy on the part of the health authorities.  The spread of the virus is then subject to extended epidemiological surveillance. The monitoring data from Santé Publique France are made available to the public in a weekly monitoring bulletin accessible online.  

 

Measuring the effectiveness of vaccines: what are the purposes?

One of the particularities of influenza vaccines is the change in their composition each year on the recommendation of the WHO, based on the viral strains that are most likely to affect populations. As a result of this particularity, the preventive approach to the epidemic also implies an estimation of the effectiveness of influenza vaccines. This estimate will be all the more accurate if it is carried out on a large scale.

 

I-MOVE: a network dedicated to measuring the effectiveness of influenza vaccines

In Europe, scientific cooperation has been at work since 2007, through I-MOVE (Influenza Monitoring Vaccine Effectiveness in Europe), a network dedicated to this measure.

I-MOVE makes its data available to health authorities as soon as possible after the start of the seasonal epidemic or pandemic. It thus offers them keys to deploy an appropriate response, and in particular:

  • Decide on the recommendations to be communicated for the use of the vaccine,
  • Target complementary or alternative measures (e.g., antivirals) for population subgroups in which the vaccine is less effective,
  • Accurately estimate the impact of current vaccination strategies on the disease to support vaccination campaigns,
  • Initiate further research on seasonal and pandemic vaccines (improve composition, use of adjuvants, need for booster doses).

 

Useful data for prevention at the global level

The network also provides guidance for other policies to prevent the global influenza epidemic. Thus, in February 2019, the data from the I-MOVE network will be made available to the the WHO committee, which will decide on the composition of the seasonal vaccine for the southern hemisphere.