My original line of thinking below is erroneous by my own standards. I have come across two names of fallacies that seem to represent the same essence:
- Appeal to the Stone which claims something is absurd (whatever that may mean) but offers no justification.
- Appeal to Ridicule which claims that something is ridiculous and therefore false.
Both are informal fallacies because in informal logic implication is taken into account in semantic interpretation in a way that a formal logic does not. If the subtext is your claim is absurd, and the debater offers neither justification and implies something is false, it would seem to meet the criteria. I'd certainly cite the latter name, and believe it qualifies as a sub-type of appeal to emotion. Sorry for my glitch!
The short answer is that there's no fallacy here. A fallacy is a persuasive, but erroneous argument, which means it must require at least two premises and a conclusion. This is just hyperbolic mockery. Often times, when a person with poor reasoning skills is confronted with a superior argument, they invoke not only fallacy, but essentially quit the argument by attempting to intimidate, mocking, or, my favorite, attempting to move the goalpost repeatedly.
A strawman fallacy would require that an argument would be made against a position you didn't actually make. E.g, if the response had been:
Oh, so you claim that the percentage is more important because SARS-CoV-2 is more infectious and deadly, but the same can be said of ebola, and that kills far fewer people than the flu. Therefore, your attempts to claim COVID-19 which is more contagious obviously is disproven.
Note, you made no claims directly about how contagious the virus is at all, but rather argued that the rate of change in the rate of infection was more concerning arguing attempting to take a position that exponential growth means that a look at numbers over time is more convincing than a direct comparison of deaths at a specific point of time.
For the record, your point about growth is more persuasive but you missed the obvious riposte which is that COVID-19 often leads to pneumonia. To wit from the WP article:
While the majority of cases result in mild symptoms, some progress to viral pneumonia and multi-organ failure.
So, to argue that pneumonia is more deadly than COVID-19 is a poor argument because it actually contributes to death by pneumonia, and therefore one cannot compare them directly because the former is caused by the latter. One could compare deaths by COVID-19 pneumonia versus influenza pneumonia, or deaths by COVID-19 versus deaths by influenza, but to compare one cause of an outcome which contributes to an outcome itself is apples and oranges.
In addition, your position has been borne out. From a CBS News article from March 9 of this year:
The CDC said that so far this season, about 20,000 people have died of the flu, including 136 children.
The CDC's most recent flu report says that as of February 29, hospitalization rates among children aged 4 and under were the highest on record at this point in the season, surpassing rates reported during the 2009 H1N1 pandemic.
Meanwhile, the number of confirmed coronavirus cases in the U.S. has surpassed 500. The new COVID-19 disease was blamed for at least 24 deaths in the U.S. as of Monday...
So around the first week of March in the US, only around 500 deaths were attributed to Covid-19 compared to 20,000 people who had the flu. But around five weeks later, we are now at the point where according to worldometers.com, deaths in the US from the latter are at almost 40,000 and are projected by the IHME to exceed 60,000 by August. To look at it another way, in 6 months this SARS virus will kill the same number of people as the very heavy flu season of 2017-2018 in the US in half the time with almost the entire country practicing social distancing!
Of course, there are other factors such as a lack of tests, a lack of vaccines, a new variation of the corona virus, and a different national strategy to mention a few which make this more deadly.