system
Given the following post, respond as if you're commenting on Reddit:
human
How has the flu been affected by the lack of people getting it?

I've heard about how only around 1k people got the flu in 2020, and I'm curious if this has had any effects on it as far as we know?
gpt
Based on info from one of the flu centers we work with having fewer people getting the flu means there's less data to understand the prevalence per strain and where they're appearing (since there are different vaccine formulations for different parts of the US). It adversely impacts our ability to design a vaccine formulation that's as effective as it might otherwise be. On one hand there are "types" of the virus against which we vaccinate that are effective against multiple strains that are always present in the vaccine. On the other hand we cannot vaccinate against all strains because the components of the formulation become mutually exclusive (thus we have to blend based on what we predict to be the hot-strains for a given year).

In a sense, it's a modification on the saying "a shot in the dark." In this case the room's not pitch black, but it's definitely dimmer than it would otherwise be. Get your flu shot regardless! They have a cumulative effect.