Winter is upon us, bringing with it a surge of viruses, including the flu. According to the World Health Organization, between 290,000 and 650,000 people die every year from the flu virus worldwide. There is therefore a clear need for effective prevention and mitigation strategies.
A JRC study finds that administering an antiviral drug as preventive action is more effective than therapy once influenza gets diagnosed, except when there’s a resistant strain of the virus with a high transmission rate. The use of a combination of antivirals in therapy considerably reduces the emergence of resistant strains.
The study analyses the use of antiviral drugs and their impact in mitigating influenza outbreaks, including mono or combination of antiviral treatment or preventive use and vaccination.
The role of antivirals
Antivirals serve as an essential treatment for vulnerable groups at high risk of severe flu complications such as the elderly, people with chronic respiratory illnesses or immunocompromised persons.
The first generation of antivirals has already been rendered worthless for treatment due to the flu virus having become resistant. It’s therefore important to understand the effects of the widespread use of newer antiviral treatments.
Epidemiological models can be used to explore the potential for drug resistance under various intervention scenarios, enhancing our understanding of how best to manage antiviral deployment alongside vaccination efforts.
Moreover, with a growing threat of bird flu, it is essential to thoroughly examine the benefits and limitations of antivirals and identify optimal intervention strategies.
JRC scientists extended a previously developed mathematical model of theirs to investigate how different strategies, including antivirals and vaccination, affect flu transmission dynamics in a population.
They compared scenarios where antivirals are given preventively (before or right after exposure to the virus) versus only treating people who show symptoms.
Preventive use of antivirals
Administering antiviral medicine before someone becomes ill (for example, after contact with a flu patient) may prevent more infections compared to treating people after symptoms appear.
However, the study finds this is only true in the absence of a resistant, highly infectious strain of the virus. Otherwise, administering antivirals to people before they start feeling the symptoms may backfire and cause a “second wave” of infections, potentially compromising the effectiveness of the antiviral in the future.
Combined therapy limits the development of drug-resistance
The findings show that when people take a combination of two antivirals, fewer people end up developing and spreading drug-resistant viruses, compared to when only one antiviral is used.
The study shows that the use of two different antivirals during therapy considerably reduces the risk of resistance emergence. It needs to be stated however that the use of additional antivirals should always be weighed against potential side effects, and this important aspect has hardly been investigated for combination therapy so far.
Vaccination is key
Finally, this JRC study confirms that high vaccination coverage is crucial in reducing the overall disease burden and may even prevent disease outbreak or spread of resistant viruses.
Researchers found that for a high vaccination coverage, flu outbreaks may be largely prevented without additional medication. Yet in many countries, vaccination coverages remain below this target. In 2021, only 51% of adults aged 65+ in the EU were vaccinated, according to the European Centre for Disease Prevention and Control.
Related content
Antiviral use and the effects of drug resistance on the transmission dynamics of influenza