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11 Nov 2020

What influenza can teach us about COVID-19

Here is the latest article in our  series of columns exploring lessons learned from previous infectious disease pandemics, and how we can apply them to the COVID-19 response.

Professor Ian Barr, Deputy Director of the WHO Collaborating Centre for Reference and Research on Influenza at the Doherty Institute looks at what learnings can be applied from influenza to COVID-19.

There are a number of things that have already been applied from what we have learned from previous influenza epidemics and pandemics that have been applied to COVID-19 control measures in Australia (and elsewhere).  Some of these are obvious and have stood the test of time since the last great influenza pandemic in 1918-19, such as quarantining, wearing of masks, social distancing, school closures, establishment of specific pandemic wards or hospitals, closure or restrictions at international borders and the somewhat more controversial measure of state border closures. All of these public health measures, that do not require any specific drugs, vaccines or high technology solutions, were introduced at various phases of the 1918-19 influenza pandemic and have been successfully utilised in Australia in various states and time points in 2020, to curb the COVID-19 pandemic.

Other measures that are already in place for influenza that might be applied to COVID-19 control in the future are the systems to deliver a large number of vaccines to people of all ages (over 6 months) over a relatively short period of time.  While the numbers to be vaccinated against COVID-19 may be higher and may be desirable to occur over a shorter time frame, we know that we are capable of maintaining the essential vaccine 'cold chain' and delivering millions of doses of vaccine over a period of a few months. 

What we don’t know yet is whether the COVID-19 vaccine will require two or more doses which is different from the influenza vaccine, which require only a single dose each year, except in young children, who require two initial doses. The frequency of vaccination for COVID-19 is also unknown at this time point as we do not know the period of protection afforded by individual vaccines, but again, even if it had to be given annually, we have shown that the current Australian medical community can cope with this for influenza and so adding another vaccine at or about the same time, should be easily achievable.

If this were the case and the two vaccines could be formulated stably together, then clearly a bivalent influenza-COVID-19 vaccine would simplify vaccination campaigns by combining the two separate vaccines into one, similar to what we do with other childhood vaccines such as MMR (measles, mumps, rubella) or DTP (diphtheria, tetanus and pertussis).

Influenza infections have the poorest outcomes in the elderly (and very elderly) similar to COVID-19. Protection of this vulnerable group against influenza, COVID-19 and in fact all respiratory pathogens is a priority now and will be a priority moving forward in future years. 

Unfortunately the elderly respond poorer to the influenza vaccine than adults and children and this is likely to be the case with COVID-19 vaccines.  Hence like influenza, protection of the elderly against COVID-19 will require multiple interventions to be applied such as; the provision of a suitable vaccine that is at least moderately efficacious in the elderly, lock-ins when community levels of disease rise, high levels of staff vaccinations, screening of any visitors or workmen, mask wearing by staff which maybe seasonal or as circumstances dictate, rapid detection of staff/residents with respiratory infections and the identification of the pathogen(s) involved with the infection and required drug treatment if appropriate.

We have learned a lot about influenza since its discovery back in the 1930’s but even with 90 years of knowledge the battle still rages globally trying to control this virus each year and similarly, we have learned a lot about COVID-19 in just 10 months since it first emerged, but the battle to control this new virus is likely to go on for many years or decades into the future, just like it has for influenza!