Countries should still be alert all the time and conduct stricter control measures to contain the spread of the novel coronavirus to avoid more deaths, World Health Organization (WHO) officials said on Friday.

At the regular WHO press conference in Geneva, Michael Ryan, executive director of WHO Health Emergencies Program, said the infection rate of the disease is still at a high level in consideration of the current situation.

Responding to lab research saying the mutation of novel coronavirus sample D614G may speed up the replication and spread of the virus, another WHO official said 29 percent of the COVID-19 samples were seen mutating.