Covid-19 is mutating, which could produce problems for any proposed vaccine:
https://www.zerohedge.com/geopolitical/scientists-discover-alarming-coronavirus-mutation-could-render-vaccine-useless
“Asked about the possibility of viral mutation during one of the White House's inaugural task force press briefings, Dr. Fauci assured the public that scientists have found "no evidence" of any concerning mutations, though the prospect that a mutated version of the virus might return during next year's flu season has kept some virologists up at night with nightmares about needing to start the vaccine clock from zero. The problem is that vaccines often aren't as effective against viruses that mutate, like the flu does every season (that's why you need to keep getting that flu shot year after year). And now, a new scientific paper that - like most of the coronavirus research being cited in the press - has yet to be peer reviewed claims to have identified a mutation in a sample of the virus collected in India that could create serious problems for researchers working on a vaccine. Monitoring the mutation dynamics of SARS-CoV-2 is critical for the development of effective approaches to contain the 21 pathogen. By analyzing 106 SARS-CoV-2 and 39 SARS genome sequences, we provided direct genetic evidence that 22 SARS-CoV-2 has a much lower mutation rate than SARS. Minimum Evolution phylogeny analysis revealed the putative original status of SARS-CoV-2 and the early-stage spread history. The discrepant phylogenies for the spike protein and it receptor binding domain proved a previously reported structural rearrangement prior to the emergence of SARS-CoV-2. Despite that, we found the spike glycoprotein of SARS-CoV-2 is particularly more conserved, we identified a mutation that leads to weaker receptor binding capability, which concerns a SARS-CoV-2 sample collected on 27th January 2020 from India. This represents the first report of a significant SARS-CoV-2 mutant, and raises the alarm that the ongoing vaccine Development may become futile in future epidemic if more mutations were identified.