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Experts note that COVID-19 has a higher hospitalization rate, as well as a higher death rate than the flu. It’s also more infectious, and there’s no vaccine yet. Fabrizio Villa/Getty Images
  • Experts say there are a number of reasons why COVID-19 is a more serious illness than the seasonal flu.
  • They point out there’s no vaccine yet for COVID-19 and community-wide immunity hasn’t built up.
  • COVID-19 is also more infectious than the flu and has a higher death rate.
  • COVID-19 also has a higher rate of hospitalizations.

On the surface, COVID-19 looks similar to the seasonal flu.

Both can cause symptoms such as fever and body aches. Both are more deadly to people over age 65.

And the viruses that cause these illnesses spread in similar ways, mainly from person to person through respiratory droplets.

But COVID-19 is not the seasonal flu.

In many ways, it’s much worse.

That can be seen by the large number of deaths that have already occurred and the way people with COVID-19 have overwhelmed hospitals in many cities around the world.

Dr. Michael Chang, an infectious disease specialist with McGovern Medical School at UTHealth in Houston, says one of the biggest challenges of SARS-CoV-2, the virus that causes COVID-19, is that it’s completely new.

That means there’s a lot we don’t know about it — how it spreads, how it infects people, how it causes damage in the body, how the immune system responds to it.

Seasonal flu, on the other hand, has been around for a long time, so scientists and doctors know a lot about it, including the best way to treat people who have the illness.

“We have more experience with the complications of flu — such as cardiac problems and bacterial pneumonias that happen after you get the flu — but with COVID-19, every treatment is essentially a trial run,” Chang told Healthline.

There’s also a yearly vaccine available for seasonal flu. While it’s not 100 percent effective, it still offers some protection and can lessen the severity of illness.

The flu vaccine doesn’t just protect people who are vaccinated. It also protects the larger community by slowing the spread of influenza viruses that are circulating.

There are also four antiviral drugs approved for treating seasonal flu. These can reduce the duration and severity of symptoms in people with the flu.

For COVID-19, a vaccine is most likely 12 to 18 months away, and there are currently no approved treatments.

The novel coronavirus also spreads more easily than most seasonal flus.

On average, one person with the coronavirus transmits it to 2 to 2.5 other people — compared with 0.9 to 2.1 other people for the flu.

People with the coronavirus can also pass it onto others for up to 3 days before they show symptoms.

If you look at the numbers of deaths from COVID-19 and seasonal flu, right now they’re not far off.

As April ended, there were more than 60,000 confirmed deaths in the United States due to COVID-19.

In 2017–2018, which was a particularly bad flu season, 61,099 people in the United States died from the flu.

But Chang points out that these COVID-19 deaths have happened over 2 months, whereas the typical flu season lasts around 5 months.

“If you took all of the flu cases and deaths and compressed them into half the time or a third of the time, suddenly you would have a big problem,” he said.

Chang adds that the total flu-related deaths are also in the context of roughly half the population vaccinated against the flu.

With the coronavirus, that kind of immunity buffer doesn’t exist.

While the United States may not have reached the peak number of COVID-19 cases and deaths are expected to continue to accumulate throughout the year.

Some epidemiologists also think that recurring waves of SARS-CoV-2 infection could last into 2022. This will require some form of physical distancing to control future outbreaks.

Had states and cities not enacted public health measures such as physical distancing and stay-at-home orders, experts say the death toll from COVID-19 could have been much worse.

A report in March by Imperial College London in the United Kingdom estimated that if we had taken no steps to slow the spread of the coronavirus, 81 percent of the population would have contracted the virus over the course of the epidemic.

The researchers say this would have resulted in the death of 2.2 million people in the United States.

This only includes deaths directly related to COVID-19. It doesn’t account for people who would have died from other causes as a result of the healthcare system being overwhelmed by patients with COVID-19.

To get a sense of the deadliness of contagious viruses, scientists look at the infection fatality rate (IFR) — the ratio of total deaths to total people with the virus.

Current estimates of the IFR for the coronavirus range from 0.4 to 1.5 percent — so anywhere from 4 to 15 times higher than the flu, which has an IFR of about 0.1 percent.

The challenge with estimating the IFR for the coronavirus is that infections are more difficult to pin down than deaths.

Many cases of SARS-CoV-2 infection are asymptomatic or may be unreported due to a shortage of testing.

The same problem occurs with tracking flu infections, but scientists have more data available from previous years that they can use to estimate flu infections in a population.

Researchers and public health groups have recently started using serological testing to better estimate the total number of people with COVID-19.

These tests look for antibodies made by the immune system to target SARS-CoV-2. If a person has these antibodies in their blood, they were likely to have had the virus — although there’s no guarantee that they’re immune.

Antibody testing in New York City suggests that 25 percent of the city’s 8.8 million residents had COVID-19 as of April 27.

This puts the IFR in New York at 0.5 to 0.8 percent, depending on whether confirmed or probably COVID-19 deaths are used. That’s as much as eight times higher than the seasonal flu.

Two recent serological studies in California, though, suggest that the IFR may be lower.

Researchers estimate that in Santa Clara County, the IFR is 0.12 to 0.2 percent. Another group estimates that in Los Angeles County, it’s 0.13 to 0.3 percent.

Both of these studies have not been published in a peer-reviewed journal, so the results should be viewed with some caution.

Other researchers have also pointed out several limitations of these studies, including statistical problems and questions about the accuracy of the tests being used.

Using data from Italy, another group of researchers estimated that the IFRs in Santa Clara County and New York City are no lower than 0.5 percent.

This study has also not been published yet in a peer-reviewed journal.

While it can be tempting to look at one city’s IFR and apply it to the rest of the country, different cities can have different IFRs.

That’s because many factors affect how many people die from COVID-19, including demographics, underlying health issues in the population, quality of the healthcare system, and the ability of the healthcare system to keep up with spikes in cases.

Dr. Matthew G. Heinz, a hospitalist and internist at Tucson Medical Center in Arizona, says even with an IFR of 0.5 percent, if we let the COVID-19 epidemic runs its course, we would see more situations like what happened in New York City, with hospitals overwhelmed by patients.

At that IFR, if 81 percent of the U.S. population had COVID-19, it would still result in more than 1 million deaths.

And again, those are just the deaths directly related to COVID-19, not those stemming from overwhelmed healthcare systems.

The impact of COVID-19 on hospitals is one of the starkest reminders that this is not just another flu.

Seasonal flu happens every year, and most hospitals are able to keep up with treating patients who are hospitalized for the illness.

Chang says there are several reasons for that.

One, because about half of Americans receive the influenza vaccine, flu viruses spread more slowly through the population. As a result, hospitalizations are stretched out over a longer period.

But as we have seen in many cities, coronavirus outbreaks can lead to large numbers of people needing to be hospitalized at the same time.

There’s also a big difference in hospitalization rates between the two illnesses.

CDC data shows that during the first 6 weeks of the 2017–2018 flu season — roughly in line with the length of the pandemic so far — 1.3 out of every 100,000 people were hospitalized.

For COVID-19, it’s nearly 30 out of every 100,000.

Even younger people are being hospitalized for COVID-19, with some being admitted to the intensive care unit (ICU).

“We cannot predict who is going to have a severe response to coronavirus,” Heinz told Healthline. “It appears to be older people and those with certain comorbidities such as diabetes, obesity, hypertension, and heart disease. But it can also affect a 22-year-old very severely, and they can die as a result.”

Patients with COVID-19 also need a lot more care than those with the flu, even those who are not in an ICU.

“Patients have a respiratory therapist visiting every 20 to 30 minutes for suctioning or additional inhaler treatments,” said Heinz. “And the nurses come in every hour, if not more often.”

The higher medical needs extend to people in the ICU.

“What we’re seeing with COVID-19 is that once the patient is on a ventilator or they need ECMO [extracorporeal membrane oxygenation], the time it takes to recover seems to be longer than compared to flu,” said Chang.

This ties up medical resources longer, not just ventilators and other equipment but also medical staff.

It also increases the risk that a healthcare system will exceed its capacity.

While some areas of the country have been spared spikes in patients with COVID-19, Chang says no area is immune to the spread of the novel coronavirus.

“If you live in an area that is relatively unaffected, that is great,” he said, “but it doesn’t mean that the coronavirus can’t become a problem in your area. And it isn’t reflective of what other people are experiencing.”

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