The flu may return, but COVID is far from over. How do they compare? - Insights+

SINCE Australia’s first wave of Omicrons after the border opened in late 2021, the pandemic has largely faded from news and public perception. Gone are the daily briefings with updates on the number of cases, hospitalizations, and deaths.

But this perception does not correspond to reality. While hospitalization and death rates are relatively lower than in previous waves – thanks to the rollout of vaccinations and naturally acquired immunity – 95% of all Australia’s COVID cases have occurred since the New Year. The daily infection rate continues to run into the tens of thousands.

Nearly 3000 Australians died from COVID in the first quarter of 2022, placing it among coronary heart disease and stroke as the leading cause of death.

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This year we have seen the Omicron wave and the resurgence of influenza. After nearly disappearing during the two-year pandemic, the lifting of most restrictions (such as social distancing and working from home), the decline in the use of masks and the opening of international borders have allowed influenza to re-emerge.

So how do COVID and seasonal influenza compare?

How deadly is COVID and influenza?

The case fatality rate – the proportion of COVID cases that die – has increased dramatically during the pandemic. In the June-October 2020 Victorian wave, about 3% of cases died.

In the 2021 Delta wave in New South Wales and Victoria, the fatality rate was under 1%.

For this year’s Omicron wave – when most of the population is vaccinated – the case fatality rate has approached 0.1%. This compares to the seasonal influenza case fatality rate seen in “normal” flu years.

This decline in the COVID case fatality rate has several causes: our high uptake of vaccinations, immunity from previous infections, better treatments, and less lethal Omicron. Contributions are relatively difficult to eliminate, but vaccination likely plays the most significant role.

The importance of COVID vaccination is underlined by a recent report estimating that internationally, the vaccine has prevented between 14.4 and 19.8 million deaths. The impact will be much greater with a more equitable distribution of global vaccines.

Which is worse for an unvaccinated person?

Starting January, Omicron causes approximately one-third the rate of hospitalization and death as the Delta variant. And for well-vaccinated people, it’s comparable to influenza.

For unvaccinated people, Omicron is still worse than influenza.

But any comparison of COVID and influenza variants is complicated by new sub-variants, reduced immunity, and the effects of boosting doses of the vaccine.

How well do vaccines protect against variants of COVID?

While Omicron is less lethal than Delta, vaccination is also less effective, especially without a third or fourth dose.

The table below is compiled from weekly reports from the UK on vaccine effectiveness, mostly among those over 50 years of age. This indicates the effectiveness of the vaccine in preventing cases has decreased with the Omicron variant.

But effectiveness in preventing hospitalization and death remains high, especially with boosters.

It is important to interpret the apparently lower protective effect of vaccination against hospitalization and death during the Omicron wave with caution. Several patients at the hospital were found incidentally to have tested positive for COVID, which did not contribute to their subsequent deaths. Vaccination can’t prevent it.

Which is more contagious – COVID or the flu?

COVID is much more contagious and spreads faster than influenza.

The first Omicron variant was estimated to be 100% more infectious than the original SARS-CoV-2 virus, and 37% more infectious than Delta. The Omicron sub-variants have successively higher infectious powers – all of them far surpassing influenza.

Seasonal influenza has a reproductive number of about 1.3 , compared with 4.2 for Omicron. That means on average one person with the flu spreads it to 1.3 other people, while one person with Omicron passes it on to 4.2 other people. It sounds simple but it is multiplied, so three flu cycles is 1.3 x 1.3 x 1.3 = 2.2 cases, while three Omikron cycles are 4.2 x 4.2 x 4.2 = 74.

As a result, we have nearly 100 times more COVID cases than influenza cases this year, and COVID is likely to remain the leading cause of hospitalization and death during the winter.

One illustration is data from the United States: in January 2022, more US children died from COVID in one month than in the previous ten years from influenza.

What might we see in the future?

Compared to many countries, Australia has managed to control COVID well. This has minimized the impact of disease and the economic burden, through the closing of international and state borders, intermittent lockdowns in some states, and the launch of a very successful early vaccine.

But the COVID pandemic is not over yet, and we will see further waves of infection with new sub-variants such as Omicron BA.4/5 (now 35% of cases in NSW), which will continue to cause illness, hospitalization and death.

Unfortunately, Australia’s use of boosters has been much slower than the initial vaccination campaign and is nearly at a standstill. This complacency is dangerous.

In the last three years we have experienced a pandemic and a series of natural disasters in Australia. The exhaustion and desire to get through COVID is completely understandable but carries a huge risk.

During winter, we must redouble our efforts to maintain population immunity through booster vaccines combined with reasonable protective measures. Make sure your COVID and influenza vaccines are up-to-date, avoid crowded places (or wear a mask if you can’t), and avoid other people if you have respiratory symptoms.

Paul GlasziouProfessor of Medicine, Bond University and David Henry, Professor of Evidence-Based Practice, Institute of Evidence-Based Health Care, Bond University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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