As President Joe Biden tries to convince Americans he’s strong enough to run for a second term, news that the Democrat caught COVID-19 drew swift reaction from supporters worried he looked “fragile” even before the diagnosis, and from those on the right theorizing this could be a ploy to swap him for someone with better odds in the presidential race. News that Biden tested positive for COVID-19 ahead of his event in Las Vegas reverberated on the internet, with many noting cases are rising nationwide. Democrats — many of whom already felt unconfident about the president’s chances to defeat form…