Trying to re-plan a trip to Chicago next year April. Will it be safe to travel?

Very unlikely to be open by April of 2021.

Try for the fall.

Even if the Covid vaccine is available and effective, there's still the possibility of getting caught up in the looting season.

I would not plan anything until late summer. IF the vaccine gets out soon it will take a lot of time for the general public to get the vaccine.

No one knows yet when it will be safe to travel, but April seems too soon. Summer may be better assuming that vaccines roll out before then,.

depends on vaccines.  if people take them.  when they get them and the results.  

also depends on WHAT you want to do in Chicago.  if you want to go to a cubs game for example, fans may not be yet allowed back in the ball parks.  

look at airline or travel options.  see if they have a flexible return policy for tickets or cancellations or rescheduling trips.  call and ask around.  check each month as it gets closer.  as with this pandemic, anything can change each week even if vaccines are being sent out.

even if vaccines come out this winter, some experts have said we won't get back to pre pandemic times until maybe for another year.  that is no mass gathering restrictions, no social distancing, etc.  

just have options ready.  hope for the best, plan for the worst.  

It will be iffy.  By then, IF the vaccines talked about work as represented, only a very small proportion of the population would have been vaccinated.  Most likely, it will take as long as a year from now until a large proportion of people will be protected.