  Tremendous effort has been given to the development of diagnostic tests,
preventive vaccines, and therapeutic medicines for coronavirus disease 2019
(COVID-19) caused by severe acute respiratory syndrome coronavirus 2
(SARS-CoV-2). Much of this development has been based on the reference genome
collected on January 5, 2020. Based on the genotyping of 6156 genome samples
collected up to April 24, 2020, we report that SARS-CoV-2 has had 4459
alarmingly mutations which can be clustered into five subtypes. We introduce
mutation ratio and mutation $h$-index to characterize the protein
conservativeness and unveil that SARS-CoV-2 envelope protein, main protease,
and endoribonuclease protein are relatively conservative, while SARS-CoV-2
nucleocapsid protein, spike protein, and papain-like protease are relatively
non-conservative. In particular, the nucleocapsid protein has more than half
its genes changed in the past few months, signaling devastating impacts on the
ongoing development of COVID-19 diagnosis, vaccines, and drugs.
