Higher influenza vaccination rates could help prevent a future pandemic by exposing new viruses like Covid-19, which was probably circulating much earlier than December 2019 but was mistaken for flu, an expert has said.

If more people were vaccinated against flu, unusually high rates of flu-like illness would be more likely to raise red flags, said Jason Kindrachuk, an assistant professor in epidemiology from the University of Manitoba. “Given that both Covid-19 and influenza share similar early symptoms of illness, influenza vaccination status provides an additional mechanism to help distinguish potential infections that could be responsible for a patient’s symptoms.

“Now I wonder how many things are written off as influenza where they may be new viruses which could impact world health.”

As the Covid-19 pandemic continues, some countries are approaching flu season. Governments have urged as many people as possible to get vaccinated against influenza to reduce the burden on health systems and virus testing labs.

Kindrachuk said flu vaccination rates had traditionally been low and authorities must focus on increasing them. He said Canada should be aiming for 80% of the population but was currently around 20%.

The World Health Organization recommends annual vaccination for high-risk groups including pregnant women, healthcare workers, people with underlying chronic conditions, the elderly and children under five.

The WHO has warned of disruption to routine immunisation activities during the pandemic because of strain on the health system and a “decreased demand for vaccination because of physical distancing requirements or community reluctance”. It says there is a high potential for outbreaks of vaccine-preventable diseases such as measles at this time, but mass vaccinations bringing together large groups of people should be avoided. Countries should instead “maintain continuity of immunisation services wherever services can be conducted under safe conditions.”

Australia and New Zealand have begun flu vaccinations early, and have prioritised the elderly, people with disabilities and health workers. Australia’s health minister, Greg Hunt, has warned of the dangers of people falling ill with both the flu and Covid-19, while his New Zealand’s counterpart, David Clark, said that although the flu shot does not protect people against Covid-19 “it will help to ‘flatten the curve’ of demand on our hospitals this winter”.

South Africa has said it will prioritise health workers for vaccinations as it does not have enough, Bloomberg has reported.

A few weeks before the known start of the coronavirus outbreak, China Daily reported the country had stockpiled twice as many vaccinations as the previous year for the coming winter and spring.

In March the Guardian revealed that some Australian jurisdictions had failed to properly stockpile a common reagent that was needed to test for Covid-19 as well as other viruses including influenza. “As the virus has spread, exhaustion of the reagents and materials required for performing diagnostic testing has resulted in decreased testing capacities which has further exacerbated the tolls from this pandemic,” said Kindrachuk.

“This is an important point as many regions, including here in Canada, have now had to adopt more stringent diagnostic testing criteria so as to preserve testing capacity as the pandemic continues.”

In recent days a study from 2017-18 has been widely shared on social media, with readers suggesting that it shows flu vaccinations increase the chance of recipients contracting a coronavirus. The WHO’s influenza team said they had not previously seen the report but a brief review of its conclusions showed there was in fact “little or no evidence of association of virus interference and influenza vaccination … Conclusions regarding the current Covid-19 pandemic and influenza vaccination cannot be made.”