"So far, this virus is relatively stable there are changes in the virus, which are expected in RNA viruses, but these changes are within the expected range and there are not any differences in the viruses that have been found in different countries that suggest that it behaves differently in terms of its ability to transmit or its ability to cause severe diseases," Van Kerkhove stated.

According to Van Kerkhove, it still has not been proven that an individual, who developed an antibody response, is necessarily immune to the virus, as existing studies on the issue are insufficient to draw definite conclusions.

"And what we are finding is that individuals, who develop an antibody response, develop it about a week or two after infection. And we are trying to better understand what that antibodies' response means. Right now, there are no studies that evaluate the antibody response as it relates to immunity. So, we cannot say that antibody response means that someone is immune. Having said that, there are a number of studies underway and this is a very active area of research," she added.

According to Johns Hopkins University's count, more than 4.1 million coronavirus cases have been confirmed worldwide including 283,000 related deaths.