The key may not be a vaccine but simply staying alive. Covid-19 kills with a "cytokine storm":

cytochine release syndrome(cytokine storm):

https://en.wikipedia.org/wiki/Cytokine_release_syndrome

Article discussing coronavirus et al and cytochine storm:

"Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China"

https://www.thelancet.com/journals/lancet/article/PIIS0140-6...

From the article:

"In view of the high amount of cytokines induced by SARS-CoV,22, 24 MERS-CoV,25, 26 and 2019-nCoV infections, corticosteroids were used frequently for treatment of patients with severe illness, for possible benefit by reducing inflammatory-induced lung injury. However, current evidence in patients with SARS and MERS suggests that receiving corticosteroids did not have an effect on mortality, but rather delayed viral clearance.27, 28, 29 Therefore, corticosteroids should not be routinely given systemically, according to WHO interim guidance."

Curcumin has been shown to suppress the cytokine storm.

https://www.ncbi.nlm.nih.gov/pubmed/25600522/

Curcumin is found in the spice turmeric and is available in most grocery stores. Today you can buy a pound of turmeric powder for ~$6. You can buy curcumin tablets in the health & fitness section.

Other anti-inflammatory agents (NSAIDS(aspirin, buprofen, naproxen),prednisone, etc.) are not as effective.

In India children are often given a daily teaspoon of turmeric (curcumin) in milk or water. India suffered much lower SARS deaths (there are confounding factors, e.g. India's high summer heat). I expect the same to happen with covid-19.