Influenza vaccination: What does the scientific proof say?



The COVID-19 pandemic has led the government to extend and reinforce their recommendations for influenza vaccination, and several Italian Regions have made it obligatory for elderly people and healthworkers. Right now, however, the most reliable studies in the elderly have shown it is useful only in people with active heart disease. For people without heart problems there is no strong evidence in its favor. The same seems true for indiscriminate vaccination of pregnant women and children. For health workers too there is no proof of net benefit, and anyway the obligation does not seem compatible with current practice.
The decision to use a quadrivalent high-dose vaccine containing strains different from those recommended by the WHO also seems criticable. In addition, the influenza vaccine suffers various drawbacks:

  • it is moderately effective against influenza, but cannot prevent the far more numerous influenza-like syndromes caused by viruses other than the influenza virus;
  • some studies indicate that it may even aggravate certain respiratory infections (viral interference), including some coronaviruses, though there is no proof of its activity on SARS-CoV-2). It is not yet clear whether it is associated with a better prognosis in patients with COVID-19.
  • there is no way to distinguish influenza syndromes from the early forms of COVID-19, which require specific diagnostic tests:
  • if it is extended, as some Regions have decided to do, the still pending highly uncertain net balance of benefits against harms will involve heavy organizational and financial costs, and much inconvenience, competing with possibly much better use of the same resources.

The best current scientific proof suggests abandoning the idea of obligatory vaccination, and waiting to further extend this vaccination, until new valid, pragmatic research, independent of commercial interests, comes up with evidence-based answers to the many open questions.