There has been much contention when Covid 19 is compared to the seasonal flu. One view is that it is much worse than the flu and the opposite view is that it no worse than a bad flu season. Here is a granular look at the numbers.
By definition, flu is defined as a contagious viral infection of the upper or lower respiratory track. Deaths caused by flu are similar to Covid 19 caused deaths in that it they induce fatal respiratory failure. Flu is caused by more than one type of virus. This definition is broad and Covid 19 could be considered a flu by this definition. However, is really isn’t important if Covid 19 is classified or considered a flu or not.
A more important question is “Does Covid 19 have a higher fatality rate than the flu?”
The CDC tracks the number of flu infections and deaths each year and the data is available online. The flu season generally occurs between November and February of each year. Since 2010, the number of deaths attributed to the flu have varied from a low of 9000 in the 2011-12 season to a high of 61,099 in the 2017-2018 flu season. There was an estimated 45-60 million people infected with the flu in 2017-18. Since 2010, there have been an average of over 37,000 deaths per flu season. This is an important benchmark because the country did not shut down under these conditions. It serves also serves as a benchmark for comparison to Covid 19 to answer the fatality question.
The flu is more fatal to those over 65. In the 2017-18 season, 50,903 of 61,009 (85%) flu deaths were in people over the age of 65. Again, there were not programs to especially protect this older segment of the population. It is also interesting to note that 80% of the deaths caused by Covid 19 are also in the over 65 age group.
On May 4, 2020, there were 69198 confirmed Covid 19 deaths in the US. These deaths occurred between February and May (3+ months), a bit shorter than the November-February flu season. This is also higher than the 61,099 flu deaths from the 2017-18 season. The number of Covid 19 deaths is still rising so there it is clear that Covid 19 has caused more fatalities than the 2017-18 flu. The final number of Covid 19 deaths has yet to be determined.
However, a more granular look at the data provides a further perspective. Specifically, comparing the number of flu deaths in 2017-18 with Covid 19 deaths, by state.
In a previous blog, it was clear that the distribution of Covid 19 deaths was not uniform across the US. In fact, New York and New Jersey account for 48% of all Covid 19 deaths while only having 9% of US population. That is, 32,800 of the Covid 19 deaths were from New York and New Jersey. The rest of the country had 36,584 deaths. This is significantly lower than the 61,099 flu deaths in 2017-2018. In other words, the statistics from New York and New Jersey make Covid 19 more deadly than the flu. However, if you do not live in New York, or New Jersey, Connecticut and Massachusetts, there will likely be more flu deaths than Covid 19 deaths. Granular Covid 19 data. How NY and New Jersey effect US Covid 19 statistics and why it matters.
Only 12 states have more Covid 19 deaths than they did in the 2017-18 flu season. https://www.cdc.gov/nchs/pressroom/sosmap/flu_pneumonia_mortality/flu_pneumonia.htm
The following graphs show the 5 states with highest numbers Covid 19 fatalities and the number of flu fatalities. The Covid 19 deaths (red) far surpass the number of flu deaths (blue).
In the other 38 states, more people died from the flu than Covid 19.
In 29 of these 38 states, there were 2-37 times more flu fatalities than Covid 19.
The following graphs shows a graph of several of the larger of the 38 states states that show the number of 2017-18 flu deaths far surpasses the number of Covid 19 deaths. These include Georgia, Texas and Florida which have begun to reopen business. Some highlights: California (2215 Covid 19 deaths vs 6340 flu deaths). Florida (1399 Covid 19 deaths vs 3057 flu deaths). North Carolina (442 Covid 19 deaths vs 2076 flu deaths).
This make answering the question of whether Covid 19 is more ‘deadly’ than the seasonal flu more difficult to answer in an absolute sense.
There are other differences between the diseases.
There is little doubt that Covid 19 is more contagious in that one Covid 19 patient infects more patients than one flu patient. However, the magnitude of this difference depends on the assumptions used to do the calculation.
It appears that up to 80% of those infected with Covid 19 have no or minor symptoms.
It also appears that respiratory failure, if it comes, can come faster with Covid 19 than the flu.
The actual number of people who have been infected with Covid 19 is still being determined. This value will come from continued antibody testing of the general population. However, the preliminary numbers indicate that the number of people infected with Covid 19 will be less than the 45-60 million who can get infected with the flu.
Last, it must be remembered that the flu mortalities are with the use of a flu vaccine. As the flu vaccine is highly variable in its effectiveness (15-50%), it is probable that the flu fatalities could be higher than Covid 19 (including NY and New Jersey) if there were no vaccine. However, with each antibody study, the number of people who have been infected with Covid 19 seems to increase. This drives the overall fatality rate down. From the antibody data available, the fatality rate is area dependent but is clearly well under 1%. This is significantly lower than the 10-15% rates being discussed in February.New York: Nearly 3 million infections – not 276,000
The flu comes back every year and tens of thousands die. The ‘herd immunity’ effect has not taken effect despite having over 50 million people a year being infected and the use of a vaccine.
The answer to the question ‘does Covid 19 have a higher fatality rate’ does not have a simple answer. The current best answer is that it depends on where you live. If you live in New York or New Jersey, Covid 19 clearly has a higher fatality rate. However, in most of the other states, there were many more flu fatalities in 2017-18 (even with a vaccine) than there are Covid 19 deaths.
As more and more restrictions are removed, it is very likely that the results will vary depending on location. As you read about the numbers, remember they are not the same everywhere, so beware of conclusions based on national numbers being applied to everyone, everywhere.
As more and more data is gathered, it appears that in states other than New York and New Jersey and perhaps one or two other states, the seasonal flu can be just as deadly if not more deadly than Covid 19.
These numbers are encouraging. We have lived with the ravages of the seasonal flu every year and it appears that we are on our way to making Covid 19 behave similarly, except for perhaps the New England states.