Offering COVID-19 and flu vaccinations together could reduce hospitalizations and deaths

Timing your COVID-19 booster with your annual flu vaccination may be a convenient and effective way to protect yourself against both viruses.

In a study published today in the Medical Journal of Australia, Burnet researchers found that offering COVID-19 vaccination boosters alongside annual influenza vaccinations could reduce the incidence of COVID-19 and associated hospital admissions.

Researchers used mathematical models to compare scenarios where COVID-19 vaccines were delivered at different times of the year and concluded that even though COVID-19 is not seasonal like influenza, increasing COVID-19 booster rates by offering them at the same time as the influenza vaccine was still likely to be an effective public health strategy.

The study estimated that there could be a 4–14% reduction in hospital admissions for COVID-19 by administering both vaccines at the same time.

In 2023, there were 62,000 hospitalizations and 3,696 deaths related to COVID-19 in Australia, more than three times the number of people who were killed on Australian roads during the same period. Despite this, in the same year only 11% of people aged over 16 years received a COVID-19 booster vaccination.

By comparison, there were 376 deaths from influenza in 2023. Annual vaccination coverage for influenza is 32%.

COVID-19 infection can lead to serious illness that can impact every system in the body, leading to a variety of health concerns including cognitive decline, immune system damage, liver impairment, kidney disease and reduced lung function. It also increases the risk of cardiovascular disease and diabetes.

Lingering infection, called long COVID, can result in sustained inflammation that can cause ongoing debilitating symptoms including severe fatigue, brain fog, headaches, chest pains, dizziness, depression and anxiety.

Burnet’s head of modeling and biostatistics and co-author of the study, Associate Professor Nick Scott, said offering both vaccinations at the same time could be a simple way to increase vaccination coverage.

“COVID-19 can lead to a range of health complications and results in more hospitalizations and deaths every year than influenza,” he said. “By offering a COVID-19 booster vaccination alongside the annual influenza vaccination, we could aim to achieve similar vaccination coverage for COVID-19 to influenza, which would make a meaningful difference in reducing hospital admissions and deaths.”

Another of the study’s co-authors, mathematical modeler Fenella McAndrew, said the research showed that getting vaccinated at any time against COVID-19 was a benefit, so it made sense to receive both vaccinations together.

“Unlike influenza, COVID-19 doesn’t have a well-defined season, and when we modeled different scenarios the percentage of people receiving booster vaccinations was more important than the timing of the vaccination,” she said.

“The COVID-19 vaccine gives 85% protection against severe disease, which is significantly higher than the influenza vaccine, which offers 44% protection against hospitalization. With such a reliable vaccine available for COVID-19, it makes sense for people to receive regular booster vaccinations to protect themselves.”

The Australian Government recommends COVID-19 booster vaccinations every 12 months for healthy adults between the ages of 18 and 64 without any risk factors. Older Australians, aged 75 and older without any risk factors, are advised to receive a booster vaccination every 6 months.